Climate change has threatened the existence of several living species, including humankind itself.
One author predicts that on the current course, climate change will lead to a mass extinction on Earth.
Still, there are people fighting to change course.
In the more than 4 billion year history of the Earth, there have been just five mass extinctions, most scientists agree. One science journalist is predicting the next one is already here — and all there is to do is slow it down.
“We are on the verge of another major mass extinction, unless we change course dramatically,” Elizabeth Kolbert, author of the Pulitzer-prize winning “The Sixth Extinction,” told CBS. “The question of how much we’re responsible for it is pretty much 100%. We have no reason to believe we would be seeing these elevated extinction rates were it not for all the ways we are changing the planet faster than other species can evolve to adapt to.”
America is changing faster than ever!Add Changing America to your Facebook or Twitter feed to stay on top of the news.
While her last book predicted that climate change would lead to mass extinction, Kolbert’s newest book, “Under a White Sky,” offers hope that humankind can change course. The book examines climate change efforts worldwide while also examining both the pros and cons of relying on technology to be the solution. Still, the New Yorker writer argues that something is better than nothing in this case.
“We have to realize that there’s a lot of damage that’s been done that’s kind of baked into this system,” Kolbert said. “We can leave a serious problem for our kids or we can leave a disastrous problem for our kids.”
WHAT YOU NEED TO KNOW ABOUT CLIMATE CHANGE RIGHT NOW
ANTHONY RICHARDSON ET AL., THE CONVERSATION10 APRIL 2021
The tropical water at the equator is renowned for having the richest diversity of marine life on Earth, with vibrant coral reefs and large aggregations of tunas, sea turtles, manta rays, and whale sharks. The number of marine species naturally tapers off as you head towards the poles.
Ecologists have assumed this global pattern has remained stable over recent centuries – until now. Our recent study found the ocean around the equator has already become too hot for many species to survive, and that global warming is responsible.
In other words, the global pattern is rapidly changing. And as species flee to cooler water towards the poles, it’s likely to have profound implications for marine ecosystems and human livelihoods. When the same thing happened 252 million years ago, 90 percent of all marine species died.
The bell curve is warping dangerously
This global pattern – where the number of species starts lower at the poles and peaks at the equator – results in a bell-shaped gradient of species richness. We looked at distribution records for nearly 50,000 marine species collected since 1955 and found a growing dip over time in this bell shape.
So, as our oceans warm, species have tracked their preferred temperatures by moving towards the poles. Although the warming at the equator of 0.6℃ over the past 50 years is relatively modest compared with warming at higher latitudes, tropical species have to move further to remain in their thermal niche compared with species elsewhere.
As ocean warming has accelerated over recent decades due to climate change, the dip around at the equator has deepened.
We predicted such a change five years ago using a modeling approach, and now we have observational evidence.
For each of the 10 major groups of species we studied (including pelagic fish, reef fish, and mollusks) that live in the water or on the seafloor, their richness either plateaued or declined slightly at latitudes with mean annual sea-surface temperatures above 20℃.
Today, species richness is greatest in the northern hemisphere in latitudes around 30°N (off southern China and Mexico) and in the south around 20°S (off northern Australia and southern Brazil).
This has happened before
We shouldn’t be surprised global biodiversity has responded so rapidly to global warming. This has happened before, and with dramatic consequences.
252 million years ago…
At the end of the Permian geological period about 252 million years ago, global temperatures warmed by 10℃ over 30,000-60,000 years as a result of greenhouse gas emissions from volcano eruptions in Siberia.
A 2020 study of the fossils from that time shows the pronounced peak in biodiversity at the equator flattened and spread. During this mammoth rearranging of global biodiversity, 90 percent of all marine species were killed.
125,000 years ago…
A 2012 study showed that more recently, during the rapid warming around 125,000 years ago, there was a similar swift movement of reef corals away from the tropics, as documented in the fossil record. The result was a pattern similar to the one we describe, although there was no associated mass extinction.
Authors of the study suggested their results might foreshadow the effects of our current global warming, ominously warning there could be mass extinctions in the near future as species move into the subtropics, where they might struggle to compete and adapt.
Today…
During the last ice age, which ended around 15,000 years ago, the richness of forams (a type of hard-shelled, single-celled plankton) peaked at the equator and has been dropping there ever since. This is significant as plankton is a keystone species in the food web.
Our study shows that decline has accelerated in recent decades due to human-driven climate change.
The profound implications
Losing species in tropical ecosystems means ecological resilience to environmental changes is reduced, potentially compromising ecosystem persistence.
In subtropical ecosystems, species richness is increasing. This means there’ll be species invaders, novel predator-prey interactions, and new competitive relationships. For example, tropical fish moving into Sydney Harbor compete with temperate species for food and habitat.
This could result in ecosystem collapse – as was seen at the boundary between the Permian and Triassic periods – in which species go extinct and ecosystem services (such as food supplies) are permanently altered.
The changes we describe will also have profound implications for human livelihoods. For example, many tropical island nations depend on the revenue from tuna fishing fleets through the selling of licenses in their territorial waters. Highly mobile tuna species are likely to move rapidly toward the subtropics, potentially beyond sovereign waters of island nations.
Similarly, many reef species important for artisanal fishers – and highly mobile megafauna such as whale sharks, manta rays, and sea turtles that support tourism – are also likely to move toward the subtropics.
The movement of commercial and artisanal fish and marine megafauna could compromise the ability of tropical nations to meet the Sustainable Development Goals concerning zero hunger and marine life.
Is there anything we can do?
One pathway is laid out in the Paris Climate Accords and involves aggressively reducing our emissions. Other opportunities are also emerging that could help safeguard biodiversity and hopefully minimize the worst impacts of it shifting away from the equator.
Currently, 2.7 percent of the ocean is conserved in fully or highly protected reserves. This is well short of the 10 percent target by 2020 under the UN Convention on Biological Diversity.
But a group of 41 nations is pushing to set a new target of protecting 30 percent of the ocean by 2030.
This “30 by 30” target could ban seafloor mining and remove fishing in reserves that can destroy habitats and release as much carbon dioxide as global aviation. These measures would remove pressures on biodiversity and promote ecological resilience.
Designing climate-smart reserves could further protect biodiversity from future changes. For example, reserves for marine life could be placed in refugia where the climate will be stable over the foreseeable future.
We now have evidence that climate change is impacting the best-known and strongest global pattern in ecology. We should not delay actions to try to mitigate this.
This story is part of Oceans 21 Our series on the global ocean opened with five in-depth profiles. Look out for new articles on the state of our oceans in the lead-up to the UN’s next climate conference, COP26. The series is brought to you by The Conversation’s international network.
A new guide to living through climate change. Robinson Meyer brings you the biggest ideas and most vital information to help you flourish on a changing planet.
Photo Illustrations by Brendan Pattengale | Maps by La Tigre
Images above: Glaciers from the Vatnajökull ice cap, in Iceland
Brendan Pattengale is a photographer who explores how color can convey emotions in an image. In his photo illustrations throughout this article, the colors of the original photos have been adjusted, but the images are otherwise unaltered.
This article was published online on February 3, 2021.
We live on a wild planet, a wobbly, erupting, ocean-sloshed orb that careens around a giant thermonuclear explosion in the void. Big rocks whiz by overhead, and here on the Earth’s surface, whole continents crash together, rip apart, and occasionally turn inside out, killing nearly everything. Our planet is fickle. When the unseen tug of celestial bodies points Earth toward a new North Star, for instance, the shift in sunlight can dry up the Sahara, or fill it with hippopotamuses. Of more immediate interest today, a variation in the composition of the Earth’s atmosphere of as little as 0.1 percent has meant the difference between sweltering Arctic rainforests and a half mile of ice atop Boston. That negligible wisp of the air is carbon dioxide.
Since about the time of the American Civil War, CO2’s crucial role in warming the planet has been well understood. And not just based on mathematical models: The planet has run many experiments with different levels of atmospheric CO2. At some points in the Earth’s history, lots of CO2 has vented from the crust and leaped from the seas, and the planet has gotten warm. At others, lots of CO2 has been hidden away in the rocks and in the ocean’s depths, and the planet has gotten cold. The sea level, meanwhile, has tried to keep up—rising and falling over the ages, with coastlines racing out across the continental shelf, only to be drawn back in again. During the entire half-billion-year Phanerozoic eon of animal life, CO2 has been the primary driver of the Earth’s climate. And sometimes, when the planet has issued a truly titanic slug of CO2 into the atmosphere, things have gone horribly wrong.
Today, humans are injecting CO2 into the atmosphere at one of the fastest rates ever over this entire, near-eternal span. When hucksters tell you that the climate is always changing, they’re right, but that’s not the good news they think it is. “The climate system is an angry beast,” the late Columbia climate scientist Wally Broecker was fond of saying, “and we are poking it with sticks.”
The beast has only just begun to snarl. All of recorded human history—at only a few thousand years, a mere eyeblink in geologic time—has played out in perhaps the most stable climate window of the past 650,000 years. We have been shielded from the climate’s violence by our short civilizational memory, and our remarkably good fortune. But humanity’s ongoing chemistry experiment on our planet could push the climate well beyond those slim historical parameters, into a state it hasn’t seen in tens of millions of years, a world for which Homo sapiens did not evolve.
When there’s been as much carbon dioxide in the air as there already is today—not to mention how much there’s likely to be in 50 or 100 years—the world has been much, much warmer, with seas 70 feet higher than they are today. Why? The planet today is not yet in equilibrium with the warped atmosphere that industrial civilization has so recently created. If CO2 stays at its current levels, much less steadily increases, it will take centuries—even millennia—for the planet to fully find its new footing. The transition will be punishing in the near term and the long term, and when it’s over, Earth will look far different from the one that nursed humanity. This is the grim lesson of paleoclimatology: The planet seems to respond far more aggressively to small provocations than it’s been projected to by many of our models.
To truly appreciate the coming changes to our planet, we need to plumb the history of climate change. So let us take a trip back into deep time, a journey that will begin with the familiar climate of recorded history and end in the feverish, high-CO2 greenhouse of the early age of mammals, 50 million years ago. It is a sobering journey, one that warns of catastrophic surprises that may be in store.
The first couple of steps back in time won’t take us to a warmer world—but they will illuminate just what sort of ill-tempered planet we’re dealing with. As we pull back even slightly from the span of recorded history—our tiny sliver of geologic time—we’ll notice almost at once that the entire record of human civilization is perched at the edge of a climate cliff. Below is a punishing ice age. As it turns out, we live on an ice-age planet, one marked by the swelling and disintegration of massive polar ice sheets in response to tiny changes in sunlight and CO2 levels. Our current warmer period is merely one peak in a mountain range, with each summit an interglacial springtime like today, and each valley floor a deep freeze. It takes some doing to escape this cycle, but with CO2 as it is now, we won’t be returning to an ice age for the foreseeable future. And to reach analogues for the kind of warming we’ll likely see in the coming decades and centuries, we will need to move beyond the past 3 million years of ice ages entirely, and make drastic jumps back into the alien Earths of tens of millions of years ago. Our future may come to resemble these strange lost worlds.
Before we move more dramatically backwards in time, let us briefly pause over the history of civilization, and then some. Ten thousand years ago, the big mammals had just vanished, at human hands, in Eurasia and the Americas. Steppes once filled with mammoths and camels and wetlands stocked with giant beavers were suddenly, stunningly vacant.
The coastlines that civilization presumes to be eternal were still far beyond today’s horizon. But the seas were rising. The doomed vestiges of mile-thick ice sheets that had cloaked a third of North American land were retreating to the far corners of Canada, chased there by tundra and taiga. The roughly 13 quintillion gallons of meltwater these ice sheets would hemorrhage, in a matter of millennia, raised the sea level hundreds of feet, leaving coral reefs that had been bathed in sunlight under shallow waves now drowned in the deep.
By 9,000 years ago, humans in the Fertile Crescent, China, Mexico, and the Andes had independently developed agriculture and—after 200,000 years of wandering—had begun to stay put. Sedentary settlements blossomed. Humans, with a surfeit of calories, began to divide their labor, and artisans plied new arts. The Earth’s oldest cities, such as Jericho, were bustling.By 5,000 years ago, sunlight had waned in the Northern summer, and rains drifted south toward the equator again. The green Sahara began to die, as it had many times before.
It’s easy to forget that the Earth—cozy, pastoral, familiar—is nevertheless a celestial body, and astronomy still has a vote in earthly affairs. Every 20,000 years or so the planet swivels about its axis, and 10,000 years ago, at civilization’s first light, the Earth’s top half was aimed toward the sun during the closest part of its orbit—an arrangement today enjoyed by the Southern Hemisphere. The resulting Northern-summer warmth turned the Sahara green. Lakes, hosting hippos, crocodiles, turtles, and buffalo, speckled North Africa, Arabia, and everywhere in between. Lake Chad, which today finds itself overtaxed and shrinking toward oblivion, was “Mega-Chad,” a 115,000-square-mile freshwater sea that sprawled across the continent. Beneath the Mediterranean today, hundreds of dark mud layers alternate with whiter muck, a barcode that marks the Sahara’s rhythmic switching from lush green to continent-spanning desert.
Imprinted on top of this cycle were the last gasps of an ice age that had gripped the planet for the previous 100,000 years. The Earth was still thawing, and amid the final approach of the rising tides, enormous plains and forests like Doggerland—a lowland that had joined mainland Europe to the British Isles—were abandoned by nomadic humans and offered to the surging seas. Vast islands like Georges Bank, 75 miles off Massachusetts—which once held mastodons and giant ground sloths—saw their menagerie overtaken. Scallop draggers still pull up their tusks and teeth today, far offshore.
By 5,000 years ago, as humanity was emerging from its unlettered millennia, the ice had stopped melting and oceans that had been surging for 15,000 years finally settled on modern shorelines. Sunlight had waned in the Northern summer, and rains drifted south toward the equator again. The green Sahara began to die, as it had many times before. Hunter-fisher-gatherers who for thousands of years had littered the verdant interior of North Africa with fishhooks and harpoon points abandoned the now-arid wastelands, and gathered along the Nile. The age of pharaohs began.
By geologic standards, the climate has been remarkably stable ever since, until the sudden warming of the past few decades. That’s unsettling, because history tells us that even local, trivial climate misadventures during this otherwise peaceful span can help bring societies to ruin. In fact, 3,200 years ago, an entire network of civilizations—a veritable globalized economy—fell apart when minor climate chaos struck.
“There is famine in [our] house; we will all die of hunger. If you do not quickly arrive here, we ourselves will die of hunger. You will not see a living soul from your land.” This letter was sent between associates at a commercial firm in Syria with outposts spread across the region, as cities from the Levant to the Euphrates fell. Across the Mediterranean and Mesopotamia, dynasties that had ruled for centuries were all collapsing. The mortuary-temple walls of Ramses III—the last great pharaoh of Egypt’s New Kingdom period—speak of waves of mass migration, over land and sea, and warfare with mysterious invaders from afar. Within decades the entire Bronze Age world had collapsed.
Historians have advanced many culprits for the breakdown, including earthquakes and rebellions. But like our own teetering world—one strained by souring trade relations, with fractious populaces led by unsteady, unscrupulous leaders and now stricken by plague—the eastern Mediterranean and the Aegean were ill-prepared to accommodate the deteriorating climate. While one must resist environmental determinism, it is nevertheless telling that when the region mildly cooled and a centuries-long drought struck around 1200 B.C., this network of ancient civilizations fell to pieces. Even Megiddo, the biblical site of Armageddon, was destroyed.
The Jökulsárlón glacier lagoon in Iceland
This same story is told elsewhere, over and over, throughout the extremely mild stretch of time that is written history. The Roman empire’s imperial power was vouchsafed by centuries of warm weather, but its end saw a return to an arid cold—perhaps conjured by distant pressure systems over Iceland and the Azores. In A.D. 536, known as the worst year to be alive, one of Iceland’s volcanoes exploded, and darkness descended over the Northern Hemisphere, bringing summer snow to China and starvation to Ireland. In Central America several centuries later, when the reliable band of tropical rainfall that rings the Earth left the Mayan lowlands and headed south, the megalithic civilization above it withered. In North America, a megadrought about 800 years ago made ancestral Puebloans abandon cliffside villages like Mesa Verde, as Nebraska was swept by giant sand dunes and California burned. In the 15th century, a 30-year drought bookended by equally unhelpful deluges brought the Khmer at Angkor low. The “hydraulic empire” had been fed and maintained by an elaborate irrigation system of canals and reservoirs. But when these canals ran dry for decades, then clogged with rains, invaders easily toppled the empire in 1431, and the Khmer forfeited their temples to the jungle.
Hopscotching through these human disasters to the present day, we pass perhaps the most familiar historical climate event of all: the Little Ice Age. Lasting roughly from 1500 to 1850, the chill made ice rinks of Dutch canals, and swelled up Swiss mountain glaciers. Tent cities sprung up on a frozen Thames, and George Washington endured his winter of cold and privation at Valley Forge in 1777 (which wasn’t even particularly harsh for the times). The Little Ice Age might have been a regional event, perhaps the product of an exceptional run of sunlight-dimming volcanism. In 1816, its annus horribilis, the so-called year without a summer—which brought snows to New England in August—global temperatures dropped perhaps a mere half a degree Celsius. While it is perennially plumbed by historians for insights into future climate change, it is not even remotely on the same scale of disruption as that which might lie in our future.
As Europe emerged from its chill, coal from 300-million-year-old jungles was being fed into English furnaces. Although the Earth was now in the same configuration that, in the previous few million years, had invited a return to deep, unthinkable ice ages, for some reason the next ice age never took. Instead the planet embarked on an almost unprecedented global chemistry experiment. Halfway through the 20th century, the climate began behaving very strangely.
So this is the climate of written history, a seemingly eventful stretch that has really been the random noise and variability of a climate essentially at peace. Indeed, if you were to find yourself in an industrial civilization somewhere else in the universe, you would almost certainly notice such similarly strange and improbably pleasant millennia behind you. This kind of climate stability seems to be a prerequisite for organized society. It is, in other words, as good as it gets.
As we jump back 20,000 years—to yesterday, geologically—the world ceases being recognizable. Whereas all of recorded history played out in a climate hovering well within a band of 1 degree Celsius, we now see what a difference 5 to 6 degrees can make—a scale of change similar to the one that humans may engineer in only the next century or so, though in this case, the world is 5 to 6 degrees colder, not warmer.
An Antarctica’s worth of ice now rests atop North America. Similar sheets smother northern Europe, and as a result, the sea level is now 400 feet lower. The midwestern United States is carpeted in stands of stunted spruce of the sort that would today look at home in northern Quebec. The Rockies are carved up, not by wildflower-dappled mountain valleys, but by overflowing rivers of ice and rock. California is a land of dire wolves. Where the Pacific Northwest edges up against the American Antarctica, it is a harsh and treeless place. Nevada and Utah fill up with cold rains.
During World War II, at Topaz, the desolate Japanese American internment camp in Utah, prisoners combed the flats of the Sevier Desert for unlikely seashells, fashioning miraculous little brooches from tiny mussel and snail shells to while away their exile. The desert seashells were roughly 20,000 years old, from the vanished depths of the giant Pleistocene-era Lake Bonneville—the product of a jet stream diverted south by the ice sheet. This was once a Utahan Lake Superior, more than 1,000 feet deep in places. It was joined by endless other verdant lakes scattered across today’s bleak Basin and Range region.
Elsewhere, the retreat of the seas made most of Indonesia a peninsula of mainland Asia. Vast savannas and swamps linked Australia and New Guinea, and of course Russia shared a tundra handshake with Alaska. There were reindeer in Spain, and glaciers in Morocco. And everywhere loess, loess, and more loess. This was the age of dust.
Ice is a rock that flows. Send it in massive sterilizing slabs across the continents, and it will quarry mountainsides, pulverize bedrock, and obliterate everything in its path. At the height of the last ice age, along the crumbling margins of the continental ice sheets, the rocky, dusty spoils of all this destruction spilled out onto the tundra. Dry winds carried this silt around the world in enormous dust storms, piling it up in seas of loess that buried the central U.S., China, and Eastern Europe under featureless drifts. In Austria, not far from the site of the voluptuous Venus of Willendorf figurine, carved some 30,000 years ago, are the remains of a campground of the same age—tents, hearths, burnt garbage pits, hoards of ivory jewelry—all abandoned in the face of these violent, smothering haboobs. Ice cores from both Antarctica and Greenland record a local environment that was 10 times dustier than today. All of this dust seeded the seas with iron, a vital nutrient for carbon-hogging plankton, which bloomed around Antarctica and pulled gigatons of CO2 out of the air and deep into the ocean, freezing the planet further.
This parched Pleistocene world would have appeared duller from space, hosting as it did a quarter less plant life. CO2 in the atmosphere registered only a paltry 180 ppm, less than half of what it is today. In fact, CO2 was so low, it might have been unable to drop any further. Photosynthesis starts to shut down at such trifling levels, a negative-feedback effect that might have left more CO2—unused by plants—in the air above, acting as a brake on the deep freeze.
This was the strange world of the Ice Age, one that, geologically speaking, is still remarkably recent. It’s so recent, in fact, that today, most of Canada and Scandinavia is still bouncing back up from the now-vanished ice sheets that had weighed those lands down.The floods carried 30-foot boulders on biblical waves, through what were suddenly the world’s wildest rapids.
In 2021, we find ourselves in an unusual situation: We live on a world with massive ice sheets, one of which covers one of the seven continents and is more than a mile deep. For most of the planet’s past, it has had virtually no ice whatsoever. The periods of extreme cold—like the ultra-ancient, phantasmagoric nightmares of Snowball Earth, when the oceans might have been smothered by ice sheets all the way to the tropics—are outliers. There were a few other surprising pulses of frost here and there, but they merely punctuate the balmy stretches of the fossil record. For almost all of the Earth’s history, the planet was a much warmer place than it is today, with much higher CO2 levels. This is not a climate-denying talking point; it’s a physical fact, and acknowledging it does nothing to take away from the potential catastrophe of future warming. After all, we humans, along with everything else alive today, evolved to live in our familiar low-CO2 world—a process that took a long time.
How long, exactly? Fifty million years ago, as our tiny mammalian ancestors were still sweating through the jungly, high-CO2 greenhouse climate they had inherited from the dinosaurs, India was nearing the end of an extended journey. Long estranged from Africa and the august, bygone supercontinent of Gondwana, the subcontinent raced northeast across the proto–Indian Ocean and smashed into Asia in slow motion. The collision not only quieted CO2-spewing volcanoes along Asian subduction zones; it also thrust the Himalayas and the Tibetan Plateau toward the stars, to be continually weathered and eroded away.
As it turns out, weathering rocks—that is, breaking them down with CO2-rich rainwater—is one of the planet’s most effective long-term mechanisms for removing carbon dioxide from the atmosphere, one that modern geoengineers are frantically trying to reproduce in a lab, for obvious reasons.
Adding to this colossal Himalayan CO2 sink, the more recent buckling, tectonic mess that lifted Indonesia and its neighbors from the sea over the past 20 million years or so also exhumed vast tracts of highly weatherable ocean crust, exposing it all to the withering assault of tropical rainstorms. Today this corroding rock accounts for roughly 10 percent of the planet’s carbon sink. Over tens of millions of years, then, the stately march of plate tectonics—the balance of volcanic CO2 and rock weathering—seems to have driven long-term climate change, in our case toward a colder, lower-CO2 world. As we’ll see, humans now threaten to undo this entire epic, geologic-scale climate evolution of the Cenozoic era—and in only a few decades.
When Earth’s blanket of CO2 was finally thin enough, the planet’s regular wobbles were at long last sufficient to trigger deep glaciations. The ice ages began. But the climate was not stable during this period. The ice advanced and retreated, and while the descent into the wild episodes of the Pleistocene epoch could be leisurely—the depths of planetary winter taking tens of thousands of years to arrive—the leap out of the cold tended to be sudden and violent. This is where positive feedback loops come in: When the last ice age ended, it ended fast.
Glacial ice near the Torfajökull volcano, in Iceland
Coral reefs marking the ancient sea level—but today lying deep off the coasts of Tahiti and Indonesia—reveal that about 14,500 years ago, the seas suddenly jumped 50 feet or so in only a few centuries, as meltwater from the late, great North American ice sheet raged down the Mississippi. When a 300-foot-deep lake of glacial meltwater spanning at least 80,000 square miles of central Canada catastrophically drained into the ocean, it shut down the churn of the North Atlantic and arrested the seaborne flow of heat northward. As a result, tundra advanced to retake much of Europe for 1,000 years. But when ocean circulation kicked back into gear, and the dense, salty seawater began to sink again, the system rebooted, and currents carried the equator’s heat toward the Arctic once more. Temperatures in Greenland suddenly leaped 10 degrees Celsius in perhaps a decade, fires spread, and revanchist forests reclaimed Europe for good.
In Idaho, ice dams that had held back giant lakes of glacial meltwater about six times the volume of Lake Erie collapsed as the world warmed, and each released 10 times the flow of all the rivers on Earth into eastern Washington. The floods carried 30-foot boulders on biblical waves, through what were suddenly the world’s wildest rapids. They left behind a labyrinth of bedrock-scoured canyons that still covers the entire southeastern corner of the state like a scar. When the Earth’s climate changes, this is what it can look like on the ground.
As the ice sheets of the Northern Hemisphere finally lost their grip, darker land around the melting margins became exposed to the sun for the first time in 100,000 years, accelerating the ice’s retreat. Permafrost melted, and methane bubbled up from thawing bogs. Colder, more CO2-soluble oceans warmed, and gave up the carbon they’d stolen in the Ice Age, warming the Earth even more. Relieved of their glacial burden, volcanoes in Iceland, Europe, and California awoke, adding even more CO2 to the atmosphere.
Soon the Sahara would green again, Jericho would be born, and humans would start writing things down. They would do so with the assumption that the world they saw was the way it had always been. “We were born only yesterday and know nothing,” one of them would write. “And our days on earth are but a shadow.”
As we leap back in time again, we emerge before the final Pleistocene glaciation. We’ve gone tremendously far back, 129,000 years, though in some ways we’ve only returned to our own world. This was the most recent interglacial period, the last of many breaks between the ice ages, and the last time the planet was roughly as warm as it is today. Once more, the seas have risen hundreds of feet, but something is awry.
As the Earth’s wobble and orbit conspired to melt more ice than the poles have shed so far today, the planet absorbed more sunlight. As a result, global temperatures were little more than 1 degree warmer than today’s Anthropocene chart-toppers—or maybe even the same. But sea level was 20 to 30 feet higher than it is now. (A full third of Florida was sunk beneath the waves.) This is “sobering,” as one paper put it.
The Dallol sulfur springs in the Danakil Depression, Ethiopia, one of the hottest places on Earth
Modelers have tried and mostly failed to square how a world about as warm as today’s could produce seas so strangely high. Provisional, if nightmarish, explanations like the runaway, catastrophic collapse of monstrous ice cliffs more than 300 feet tall in Antarctica, which may or may not be set into motion in our own time, are fiercely debated in conference halls and geoscience departments.
Very soon, we may well have warmed the planet enough to trigger similarly dramatic sea-level rise, even if it takes centuries to play out. This is what the Exxon scientist James Black meant in 1977 when he warned higher-ups of the coming “super-interglacial” that would be brought about—as a matter of simple atmospheric physics—from burning fossil fuels. But our trajectory as a civilization is headed well beyond the warmth of the last interglacial, or any other interglacial period of the Pleistocene, for that matter. So it’s time to keep moving. We must take our first truly heroic leap into geologic time, millions of years into the past.
We’re more than 3 million years in the past now, and carbon dioxide in the atmosphere is at 400 parts per million, a level the planet will not again see until September 2016. This world is 3 to 4 degrees Celsius warmer than ours, and the sea level is up to 80 feet higher. Stunted beech trees and bogs line the foothills of the Transantarctic Mountains not far from the South Pole—the last members of a venerable line of once-majestic forests that had existed since long before the age of the dinosaurs.
What we’ve glossed over in our journey back to this ancient present: the entire evolutionary history of Homo sapiens, three Yellowstone super-eruptions, thousands of megafloods, the last of the giant terror birds, a mass extinction of whales, and the glacial creation and destruction of innumerable islands and moraines. As we make our way backwards in time to the Pliocene, the glaciations get briefer, and the ice sheets themselves become thinner and more temperamental. About 2.6 million years ago they all but disappear in North America, as CO2 levels continue their slow climb.
When we arrive in the middle of the Pliocene, just over 3 million years ago, CO2 levels are high enough that we’ve escaped the cycle of ice ages and warm interglacials altogether. Lucy the Australopithecus roams a heavily forested East Africa. We are now outside the evolutionary envelope of our modern world, sculpted as it was by the temperamental northern ice sheets and deep freezes of the Pleistocene. But as to atmospheric carbon dioxide, 3 million years is how far back we have to go to arrive at an analogue for 2021.
Despite the similarities between our world and that of the Pliocene, the differences are notable. In the Canadian High Arctic—where today tundra spreads to the horizon—evergreen forests come right to the edge of an ice-free Arctic Ocean. Though the world as a whole is only a few degrees warmer, the Arctic, as always, gets the brunt of the extra heat. This is called “polar amplification,” and it’s why maps of modern warming are crowned by a disturbing fog of maroon. Models struggle to reproduce the extreme level of warming in the Pliocene Arctic. It’s a full 10 to 15 degrees Celsius warmer in the long twilight of northern Canada, and the pine and birch woodlands of these Arctic shores are filled with gigantic forest-dwelling camels. Occasionally this boreal world erupts in wildfire, a phenomenon echoed by the blazes that today sweep ever farther north. Elsewhere, West Antarctica’s ice sheet may have disappeared entirely, and Greenland’s, if it exists at all, is shriveled and pathetic.
A common projection for our own warming world is that, while the wet places will get wetter, the dry places will get drier. But the Pliocene seems to defy this saw for reasons not yet fully understood. It’s a strangely wet world, especially the subtropics, where—in the Sahara, the Outback, the Atacama, the American Southwest, and Namibia—lakes, savannas, and woodlands replace deserts. This ancient wetness might come down to inadequacies in how we model clouds, which are under no obligation to behave in physical reality as they do in simplified lines of computer code. Hurricanes were almost certainly more consistently punishing 3 million years ago, just as our storms of the future will be. And a more sluggish circulation of the atmosphere might have lulled the trade winds, turning El Niño into “El Padre.” Perhaps this is what brought rains—and lakes—to the Mojave at this time.
Angeles National Forest, California
Our modern coastlines would have been so far underwater that you’d have to take great pains to avoid getting the bends if you tried scuba diving down to them. Today, traveling east through Virginia, or North or South Carolina, or Georgia, midway through your drive you’ll pass over a gentle 100-foot drop. This is the Orangeburg Scarp, a bluff—hundreds of miles long—that divides the broad, flat coastal plain of the American Southeast. It comprises the eroded and smoothed-out rumors of once-magnificent sea cliffs. Here, waves of the Pliocene high seas chewed away at the middle of the Carolinas—an East Coast Big Sur. This ancient shoreline is visible from space by the change in soil color that divides the states, and is visible on much closer inspection as well: To the east of this strange drop-off, giant megalodon-shark teeth and whale bones litter the Carolina Low Country. Though warped over the ages by the secret workings of the mantle far below, these subtle banks 90 miles inland nevertheless mark the highest shoreline of the Pliocene, when the seas were dozens of feet higher than they are today. But even within this warm Pliocene period, the sea level leaped and fell by as much as 60 feet every 20,000 years, to the rhythm of the Earth’s sway in space. This is because, under this higher-CO2 regime, the unstable ice sheet in Antarctica took on the volatile temperament that, 1 million years later, would come to characterize North America’s ice sheet, toying with the ancient coastline as if it were a marionette.
So this is the Pliocene, the world of the distant present. While today’s projections of future warming tend to end in 2100, the Pliocene illuminates just what sort of long-term changes might inevitably be set in motion by the atmosphere we’ve already engineered. As the great ice sheets melt, the permafrost awakens, and darker forested land encroaches on the world’s tundra, positive feedbacks may eventually launch our planet into a different state altogether, one that might resemble this bygone world. Nevertheless, human civilization is unlikely to keep atmospheric CO2 at a Pliocene level—so more ancient and extreme analogues must be retrieved.
We’re now deeper in the past, and the planet appears truly exotic. The Amazon is running backwards, and gathers in great pools at the foot of the Andes. A seaway stretches from Western Europe to Kazakhstan and spills into the Indian Ocean. California’s Central Valley is open ocean.
What today is the northwestern U.S. is especially unrecognizable. Today the airy, columnated canyons of the Columbia River in Oregon swarm with tiny kiteboarders zipping through gorges of basalt. But 16 million years ago, this was a black, unbreathable place, flowing with rivers of incandescent rock. The Columbia River basalts—old lava flows that spread across Washington, Oregon, and Idaho, in some places more than two miles thick—were the creation of a class of extremely rare and world-changing volcanic eruptions known as large igneous provinces, or LIPs.
Some LIPs in Earth’s history span millions of square miles, erupt for millions of years, inject tens of thousands of gigatons of CO2 into the air, and are responsible for most of the worst mass extinctions in the history of the planet. They live up to their name—they are large. But these mid-Miocene eruptions were still rather small as far as LIPs go, and so the planet was spared mass death. Nevertheless, the billowing volcanoes raised atmospheric CO2 up to about 500 ppm, a level that today represents something close to the most ambitious and optimistic scenario possible for limiting our future carbon emissions.
In the Miocene, this volcanic CO2 warmed up the world to at least 4 degrees Celsius and perhaps as much as 8 degrees above modern temperatures. As a result, there were turtles and parrots in Siberia. Canada’s Devon Island, in the high Arctic, is today a desolate wasteland, the largest uninhabited island in the world—and one used by NASA to simulate life on Mars. In the Miocene, its flora resembled Lower Michigan’s.
The sweeping grasslands distinctive to our cooler, drier, low-CO2 world had yet to take over the planet, and so forests were everywhere—in the middle of Australia and Central Asia and Patagonia. All of this vegetation was one of the reasons it was so warm. Forests and shrubs made this planet darker than our own world—one still painted pallid hues in many places by bare land and ice—and allowed it to absorb more heat. This change in the planet’s color is just one of the many long-term feedback loops awaiting us after the ice melts. Long after our initial pulse of CO2, they will make our future world warmer and more alien still.
As for fauna, we’re now so distantly marooned in time from our own world that most of the creatures that inhabited this leafy planet range from the flatly unfamiliar to the uncannily so. There were big cats that weren’t cats, and rhino-size “hell pigs” that weren’t pigs. There were sloths that lived in the ocean and walruses that weren’t related to today’s walruses. Earth’s largest-ever meat-eating land mammals, African juggernauts like Megistotherium and Simbakubwa, not closely related to any living mammals today, tore early elephants apart with bladed mouths.
And with CO2 at 500ppm, the sea level was about 150 feet higher than today. Approaching Antarctica in the middle Miocene by sea, the waters would be warmer than today, and virtually unvisited by ice. To get to the ice sheet, you’d have to hike far past lakes and forests of conifers that lined the coast. Trudging past the trees and finally over endless tundra, you would come at last to the edge of a much smaller ice sheet whose best days were still ahead of it. An axiom about this land-based Antarctic ice sheet in paleoclimatology is that it’s incredibly stubborn. That is, once you have an ice sheet atop the heart of Antarctica, feedback loops kick in to make it exceedingly hard to get rid of. Barring true climatic madness, a land-based Antarctic ice sheet is essentially there to stay.
Clouds in Death Valley, California
But in the middle Miocene this young Antarctic ice sheet seemed to have a temper. It might have been “surprisingly dynamic,” as one paper cheerfully puts it. As CO2 increased from just below today’s levels up to about 500ppm, Miocene Antarctica shed what today would amount to 30 to 80 percent of the modern ice sheet. In the Miocene, Antarctica seemed exquisitely tuned to small changes in atmospheric CO2, in ways that we don’t fully understand and that we’re not incorporating into our models of the future. There will undoubtedly be surprises awaiting us in our high-CO2 future, just as there were for life that existed in the Miocene. In fact, the Antarctic ice sheet may be more vulnerable today to rapid retreat and disintegration than at any time in its entire 34-million-year history.
In the 16 million years since this mid-Miocene heat, the volcanic hot spot responsible for the Columbia River basalts has wandered under Yellowstone. Today it powers a much tamer kind of volcano. It could cover a few states in a few inches of ash and disrupt global agriculture for years, but it couldn’t launch the planet into a new climate for hundreds of thousands of years, or kill most life on the surface. Unfortunately, there is such a supervolcano active on Earth today: industrial civilization. With CO2 likely to soar past 500ppm from future emissions, even the sweat-soaked, Siberian-parrot-populated world of the middle Miocene might not tell us everything we need to know about our future climate. It’s time to go back to a global greenhouse climate that ranks among the warmest climate regimes complex life has ever endured. In our final leap backwards, CO2 at last reaches levels that humans might reproduce in the next 100 years or so. What follows is something like a worst-case scenario for future carbon emissions. But these worst-case projections have continued to prove stubbornly accurate in the 21st century so far, and they remain a possible path for our future.
We’re now about to take our largest leap, by far, into the geologic past. We hurdle over 40 million years of history, past volcanic eruptions thousands of times bigger than that of Mount St. Helens, past an asteroid impact that punched out a gigantic crater where the Chesapeake Bay sits today. The Himalayas slump; India unhitches from Asia; and the further back we go, the higher the CO2 level rises and the warmer the Earth gets. The Antarctic ice sheet, in its death throes, vanishes altogether, and the polar continent instead gives way to monkey puzzle trees and marsupials. We have arrived, finally at the end of our journey, in the greenhouse world of the early age of mammals.
Today the last dry land one steps on in Canada before setting out across the ice-choked seas for the North Pole is Ellesmere Island, at the top of the world. But once upon a time there was a rainforest here. We know this because tree stumps still erode out of the barren hillsides, and they’re more than 50 million years old. They’re all that’s left of an ancient polar jungle now whipped by indifferent Arctic winds. But once upon a time, this island was a swampy cathedral of redwoods, whose canopy naves were filled with flying lemurs, giant salamanders, and hippolike beasts that pierced the waters. At this polar latitude, on some late-fall evening of the early Eocene, the sun tried and failed to lift itself from the horizon. A pink twilight reached deep into the jungle, but soon the sun would set entirely here for more than four months. In this unending Arctic dark, the stillness would be broken by the orphaned calls of tiny early primates, who hopped fearlessly over stilled alligators that would start moving again when the sun returned from beyond the horizon. In this unending night, tapirs hunted for mushrooms and munched on leaf litter that was left over from sunny days past and that in the far future would become coal.Humans now threaten to undo the entire climate evolution of the Cenozoic era—and in only a few decades.
We have no modern analogue for a swampy rainforest teeming with reptiles that nevertheless endures months of Arctic twilight and polar night. But for each degree Celsius the planet warms, the atmosphere holds about 6 percent more water vapor, and given that global temperatures at the beginning of the age of mammals were roughly 13 degrees warmer than today, it’s difficult to imagine how uncomfortable this planet would be for Ice Age creatures like ourselves. In fact, much of the planet would be rendered off-limits to us, far too hot and humid for human physiology.
Not only was this a sweltering age, but it was also one cruelly punctuated by some of the most profound and sudden CO2-driven global-warming events in geologic history—on top of this already feverish baseline. Deep under the North Atlantic, the Eocene epoch kicked off in style 56 million years ago with massive sheets of magma that spread sideways through the crust, igniting vast, diffuse deposits of fossil fuels at the bottom of the ocean. This ignition of the underworld injected something like the carbon equivalent of all currently known fossil-fuel reserves into the seas and atmosphere in less than 20,000 years, warming the planet by another 5 to 9 degrees Celsius. Evidence abounds of violent storms and megafloods during this ancient spasm of climate change—episodic waves of torrential rains unlike any on Earth today. In some places, such storms would have been routine, separated by merciless droughts and long, brutal, cloudless heat waves. Seas near the equator may have been almost as hot as a Jacuzzi—too hot for most complex life. As for the rest of the planet, all of this excess CO2 acidified the oceans, and the world’s coral reefs collapsed. Ocean chemistry took 200,000 years to recover.
The most jarring thing about the early age of mammals, though, isn’t merely the extreme heat. It’s the testimony of the plants. In higher-CO2 conditions, plants reduce the number of pores on their leaves, and fossil leaves from the jungles of the early Eocene have tellingly fewer pores than today’s. By some estimates, CO2 50 million years ago was about 600 ppm. Other proxies point to higher CO2, just over 1,000 ppm, but even that amount has long bedeviled our computer models of climate change. For years, in fact, models have told us that to reproduce this feverish world, we’d need to ramp up CO2 to more than 4,000 ppm.
This ancient planet is far more extreme than anything being predicted for the end of the century by the United Nations or anyone else. After all, the world that hosted the rainforests of Ellesmere Island was 13 degrees Celsius warmer than our own, while the current global ambition, enshrined in the Paris Agreement, is to limit warming to less than 2, or even 1.5, degrees. Part of what explains this glaring disparity is that most climate projections end at the end of the century. Feedbacks that might get you to Eocene- or Miocene-level warmth play out over much longer timescales than a century. But the other, much scarier insight that Earth’s history is very starkly telling us is that we have been missing something crucial in the models we use to predict the future.
Mount Ruapehu and Mount Ngauruhoe volcanoes, in New Zealand
Some of the models are starting to catch up. In 2019, one of the most computationally demanding climate models ever run, by researchers at the California Institute of Technology, simulated global temperatures suddenly leaping 12 degrees Celsius by the next century if atmospheric CO2 reached 1,200ppm—a very bad, but not impossible, emissions pathway. And later that year, scientists from the University of Michigan and the University of Arizona were similarly able to reproduce the warmth of the Eocene by using a more sophisticated model of how water behaves at the smallest scales.
The paleoclimatologist Jessica Tierney thinks the key may be the clouds. Today, the San Francisco fog reliably rolls in, stranding bridge towers high above the marine layer like birthday candles. These clouds are a mainstay of west coasts around the world, reflecting sunlight back to space from coastal California and Peru and Namibia. But under higher-CO2 conditions and higher temperatures, water droplets in incipient clouds could get bigger and rain down faster. In the Eocene, this might have caused these clouds to fall apart and disappear—inviting more solar energy to reach, and warm, the oceans. That might be why the Eocene was so outrageously hot.
This sauna of our early mammalian ancestors represents something close to the worst possible scenario for future warming (although some studies claim that humans, under truly nihilistic emissions scenarios, could make the planet even warmer). The good news is the inertia of the Earth’s climate system is such that we still have time to rapidly reverse course, heading off an encore of this world, or that of the Miocene, or even the Pliocene, in the coming decades. All it will require is instantaneously halting the super-eruption of CO2 disgorged into the atmosphere that began with the Industrial Revolution.
We know how to do this, and we cannot underplay the urgency. The fact is that none of these ancient periods is actually an apt analogue for the future if things go wrong. It took millions of years to produce the climates of the Miocene or the Eocene, and the rate of change right now is almost unprecedented in the history of animal life.
Humans are currently injecting CO2 into the air 10 times faster than even during the most extreme periods within the age of mammals. And you don’t need the planet to get as hot as it was in the early Eocene to catastrophically acidify the oceans. Acidification is all about the rate of CO2 emissions, and we are off the charts. Ocean acidification could reach the same level it did 56 million years ago by later this century, and then keep going.
When he coined the term mass extinction in a 1963 paper, “Crises in the History of Life,” the American paleontologist Norman Newell posited that this was what happened when the environment changed faster than evolution could accommodate. Life has speed limits. And in fact, life today is still trying to catch up with the thaw-out of the last ice age, about 12,000 years ago. Meanwhile, our familiar seasons are growing ever more strange: Flycatchers arrive weeks after their caterpillar prey hatches; orchids bloom when there are no bees willing to pollinate them. The early melting of sea ice has driven polar bears ashore, shifting their diet from seals to goose eggs. And that’s after just 1 degree of warming.
Subtropical life may have been happy in a warmer Eocene Arctic, but there’s no reason to think such an intimately adapted ecosystem, evolved on a greenhouse planet over millions of years, could be reestablished in a few centuries or millennia. Drown the Florida Everglades, and its crocodilians wouldn’t have an easy time moving north into their old Miocene stomping grounds in New Jersey, much less migrating all the way to the unspoiled Arctic bayous if humans re-create the world of the Eocene. They will run into the levees and fortifications of drowning Florida exurbs. We are imposing a rate of change on the planet that has almost never happened before in geologic history, while largely preventing life on Earth from adjusting to that change.
Taking in the whole sweep of Earth’s history, now we see how unnatural, nightmarish, and profound our current experiment on the planet really is. A small population of our particular species of primate has, in only a few decades, unlocked a massive reservoir of old carbon slumbering in the Earth, gathering since the dawn of life, and set off on a global immolation of Earth’s history to power the modern world. As a result, up to half of the tropical coral reefs on Earth have died, 10 trillion tons of ice have melted, the ocean has grown 30 percent more acidic, and global temperatures have spiked. If we keep going down this path for a geologic nanosecond longer, who knows what will happen? The next few fleeting moments are ours, but they will echo for hundreds of thousands, even millions, of years. This is one of the most important times to be alive in the history of life.
Smoke and flames rise from an illegal fire in the Amazon rainforest reserve, south of Novo Progresso in Para state, Brazil. Photograph: Carl de Souza/AFP/GettyThe age of extinction is supported by
The planet is facing a “ghastly future of mass extinction, declining health and climate-disruption upheavals” that threaten human survival because of ignorance and inaction, according to an international group of scientists, who warn people still haven’t grasped the urgency of the biodiversity and climate crises.
The 17 experts, including Prof Paul Ehrlich from Stanford University, author of The Population Bomb, and scientists from Mexico, Australia and the US, say the planet is in a much worse state than most people – even scientists – understood.
“The scale of the threats to the biosphere and all its lifeforms – including humanity – is in fact so great that it is difficult to grasp for even well-informed experts,” they write in a report in Frontiers in Conservation Science which references more than 150 studies detailing the world’s major environmental challenges.Advertisementhttps://7552e34cf58bb69b7407b7a56eee25ae.safeframe.googlesyndication.com/safeframe/1-0-37/html/container.html
The delay between destruction of the natural world and the impacts of these actions means people do not recognise how vast the problem is, the paper argues. “[The] mainstream is having difficulty grasping the magnitude of this loss, despite the steady erosion of the fabric of human civilisation.”
The report warns that climate-induced mass migrations, more pandemics and conflicts over resources will be inevitable unless urgent action is taken.
“Ours is not a call to surrender – we aim to provide leaders with a realistic ‘cold shower’ of the state of the planet that is essential for planning to avoid a ghastly future,” it adds.
Dealing with the enormity of the problem requires far-reaching changes to global capitalism, education and equality, the paper says. These include abolishing the idea of perpetual economic growth, properly pricing environmental externalities, stopping the use of fossil fuels, reining in corporate lobbying, and empowering women, the researchers argue.
The report comes months after the world failed to meet a single UN Aichi biodiversity target, created to stem the destruction of the natural world, the second consecutive time governments have failed to meet their 10-year biodiversity goals. This week a coalition of more than 50 countries pledged to protect almost a third of the planet by 2030.
A coral reef dominated by algae in Seychelles … the climate crisis is changing the composition of ecosystems. Photograph: Nick Graham/Lancaster University/PA
An estimated one million species are at risk of extinction, many within decades, according to a recent UN report.
“Environmental deterioration is infinitely more threatening to civilisation than Trumpism or Covid-19,” Ehrlich told the Guardian.
In The Population Bomb, published in 1968, Ehrlich warned of imminent population explosion and hundreds of millions of people starving to death. Although he has acknowledged some timings were wrong, he has said he stands by its fundamental message that population growth and high levels of consumption by wealthy nations is driving destruction.
He told the Guardian: “Growthmania is the fatal disease of civilisation – it must be replaced by campaigns that make equity and well-being society’s goals – not consuming more junk.”
Large populations and their continued growth drive soil degradation and biodiversity loss, the new paper warns. “More people means that more synthetic compounds and dangerous throwaway plastics are manufactured, many of which add to the growing toxification of the Earth. It also increases the chances of pandemics that fuel ever-more desperate hunts for scarce resources.”Mass die-off of birds in south-western US ’caused by starvation’Read more
The effects of the climate emergency are more evident than biodiversity loss, but still, society is failing to cut emissions, the paper argues. If people understood the magnitude of the crises, changes in politics and policies could match the gravity of the threat.
“Our main point is that once you realise the scale and imminence of the problem, it becomes clear that we need much more than individual actions like using less plastic, eating less meat, or flying less. Our point is that we need big systematic changes and fast,” Professor Daniel Blumstein from the University of California Los Angeles, who helped write the paper, told the Guardian.
The paper cites a number of key reports published in the past few years including:
The World Economic Forum report in 2020, which named biodiversity loss as one of the top threats to the global economy.
The 2020 WWF Living Planet report, which warned the average population size of vertebrates had declined by 68% in the past five years.
A 2018 Intergovernmental Panel on Climate Change report which said that humanity had already exceeded global warming of 1C above pre-industrial levels and is set to reach 1.5C warming between 2030 and 2052.
Australia saw a devastating bushfire season in 2020. Photograph: Tracey Nearmy/Reuters
Advertisement
The report follows years of stark warnings about the state of the planet from the world’s leading scientists, including a statement by 11,000 scientists in 2019 that people will face “untold suffering due to the climate crisis” unless major changes are made. In 2016, more than 150 of Australia’s climate scientists wrote an open letter to the then prime minister, Malcolm Turnbull, demanding immediate action on reducing emissions. In the same year, 375 scientists – including 30 Nobel prize winners – wrote an open letter to the world about their frustrations over political inaction on climate change.
Prof Tom Oliver, an ecologist at the University of Reading, who was not involved in the report, said it was a frightening but credible summary of the grave threats society faces under a “business as usual” scenario. “Scientists now need to go beyond simply documenting environmental decline, and instead find the most effective ways to catalyse action,” he said.
Prof Rob Brooker, head of ecological sciences at the James Hutton Institute, who was not involved in the study, said it clearly emphasised the pressing nature of the challenges.
“We certainly should not be in any doubt about the huge scale of the challenges we are facing and the changes we will need to make to deal with them,” he said.
From the Pope to Greta Thunberg, there are growing calls for the crime of “ecocide” to be recognised in international criminal law – but could such a law ever work?I
In December 2019, at the International Criminal Court in the Hague, Vanuatu’s ambassador to the European Union made a radical suggestion: make the destruction of the environment a crime.
Vanuatu is a small island state in the South Pacific, a nation severely threatened by rising sea levels. Climate change is an imminent and existential crisis in the country, yet the actions that have caused rising temperatures – such as burning fossil fuels – have almost entirely taken place elsewhere, to serve other nations, with the blessing of state governments.
Small island states like Vanuatu have long tried to persuade large powerful nations to voluntarily reduce their emissions, but change has been slow – so ambassador John Licht suggested that it might be time to change the law itself. An amendment to a treaty known as the Rome Statute, which established the International Criminal Court, could criminalise acts that amount to ecocide, he said, arguing “this radical idea merits serious discussion”.
Campaigners are calling for the destruction of nature to be recognised as an international crime (Credit: Getty Images)
Ecocide – which literally means “killing the environment” – is an idea that seems both a highly radical and, campaigners claim, a reasonable one. The theory is that no one should go unpunished for destroying the natural world. Campaigners believe the crime should come under the jurisdiction of the International Criminal Court, which can currently prosecute just four crimes: genocide, crimes against humanity, war crimes and crimes of aggression.
If something’s a crime, we place it below a moral red line – Jojo Mehta
While the International Criminal Court can already prosecute for environmental crimes, this is only possible within the context of these four crimes – it does not place any legal restrictions on legal harms that occur during times of peace. While individual countries have their own rules and regulations to prevent such harms, ecocide campaigners argue that mass environmental destruction will continue until a global law is in place.
This wouldn’t be the fluffy and arguably toothless rulemaking that often emerges from international processes – such as the Paris Agreement on climate change, where countries set their own emissions reductions targets. By adding a fifth crime of ecocide to the Rome Statute of the International Criminal Court, the perpetrators of environmental destruction would suddenly be liable to arrest, prosecution and imprisonment.
But it would also help to create a cultural shift in how the world perceives acts of harm towards nature, says Jojo Mehta, co-founder of the Stop Ecocide campaign.
“If something’s a crime, we place it below a moral red line. At the moment, you can still go to the government and get a permit to frack or mine or drill for oil, whereas you can’t just get a permit to kill people, because it’s criminal,” she says. “Once you set that parameter in place, you shift the cultural mindset as well as the legal reality.”
Jojo Mehta argues that a law against ecocide would hold to account people who cause significant damage to the environment (Credit: Ruth Davey/Look Again Photography)
Campaigners believe the crime of ecocide should only apply to the most serious harms, encompassing activities like oil spills, deep-sea mining, industrial livestock farming and tar sand extraction. In 2010, Polly Higgins, a British barrister, defined ecocide as “extensive damage… to such an extent that peaceful enjoyment by the inhabitants of that territory has been or will be severely diminished.”
The mother of all battles is international: to ensure that this term is enshrined in international law – Emmanuel Macron
Last year, Higgins died aged 50, after being diagnosed with cancer. It was a blow for the ecocide movement – she had been its leading legal light and fiercest advocate, selling her house and giving up her high-paying job in order to dedicate her life to the campaign. Despite her passing, that the movement now appears to be gaining momentum. After decades of existing at the radical fringes of the environmental movement, ecocide is now being discussed by parliamentarians and leaders across the world.
Among them is Emmanuel Macron, the president of France, who has become one of ecocide’s highest profile supporters. Earlier this year, more than 99% of the French citizens’ assembly, a group of 150 people selected by lot to guide the country’s climate policy, voted to make ecocide a crime. That prompted Macron to announce that the government would consult with legal experts on how to incorporate it into French law. But he went further. “The mother of all battles is international: to ensure that this term is enshrined in international law so that leaders… are accountable before the International Criminal Court,” he responded to the assembly.
Elsewhere in Europe, Belgium’s two Green parties have introduced an ecocide bill that proposes addressing the issue at both a national and international level – an idea that also has support among Swedish parliamentarians. “We have all the conventions, we have all the goals. But the beautiful visions must go from paper into action,” said Rebecka Le Moine, the Swedish MP who submitted a motion to her national parliament. “If these actions should be anything more than goodwill or activism, it must become law.”
Pope Francis has also called for ecocide to be recognised as a crime by the international community, and Greta Thunberg has backed the cause too, donating €100,000 (£90,000) in personal prize winnings to the Stop Ecocide Foundation.
Supporters of a law against ecocide argue it would place emphasis on the environmental and human costs of issues such as climate change (Credit: Getty Images)
Even so, the concept of ecocide has its limitations. David Whyte, professor of socio-legal studies at the University of Liverpool and author of a book called Ecocide, warned that an international law would not be a silver bullet that eradicates environmental destruction. Corporations cannot be prosecuted under international criminal law, which only applies to individuals, Whyte points out – and bringing down a CEO may not actually rein in the business itself.
“It’s really important to change our language and the way we think about what’s harming the planet – we should push through this crime of ecocide – but it’s not going to change anything unless, at the same time, we change the model of corporate capitalism,” he says.
“You can never say never – and it’s gaining momentum that we maybe would never have imagined previously – but the challenges are still so significant. First of all, you have political resistance. I think the chance of an assembly of state parties agreeing to an additional crime is unlikely, particularly one that might curb economic expansion,” she says.
Greta Thunberg is among those calling for ecocide to be recognised as a crime (Credit: Getty Images)
An international law on ecocide would also be difficult from a legal perspective, adds Killean – lawyers would have to ensure that there were sufficient grounds for prosecution.
“If you think about all the parts of the criminal prosecution, you need to have an individual – so who’s the individual that’s responsible for ecocide? There needs to be intention – so how do you prove intention for the destruction of a territory? All these different things that build up a criminal trial become really complicated when you’re thinking about ecocide.”
Campaigners like Mehta understand these difficulties. Her campaign group, Stop Ecocide, is currently pulling together a panel of top international lawyers to write a “clear and legally robust” definition of ecocide that countries could propose at the International Criminal Court.
Once that’s in place, the next step would be for a country to back it at The Hague. While Vanuatu has raised the issue, it did not submit a formal proposal to amend the Rome Statute, and whether there will be a government brave enough to do so remains an open question – leading on such an issue requires a certain level of diplomatic clout. Mehta believes that such a move is becoming more likely due to the growing number of governments that have expressed their theoretical support. “There’s safety in numbers,” she says. “It’s less of a political risk.”
But the journey wouldn’t end there. Once a proposal is submitted, it would have to be adopted by a two-thirds majority vote – in practice, that means it needs the support of 82 countries. No country has veto power, and all nations have the same voting power regardless of size or wealth. It’s a process that Mehta envisages taking anywhere between three and seven years.
Whether or not the process happens so quickly, or if it even happens at all, ecocide has proved to be a powerful idea. It has crystallised a concept that often gets lost in discussions of policy and technology: that many see that there is a moral red line when it comes to destroying the environment. And it is a reminder that it is not a victimless act: when forests burn and oceans rise, humans are suffering around the world. Moreover, the perpetrators of these acts are not blameless. For campaigners like Mehta, criminalising ecocide is a way to call time on the destruction of the Earth’s ecosystems and those who live in them.
In 2015, Stanford biologist Paul Ehrlich coauthored a study declaring the
world’s sixth mass extinction was underway. Five years later, Ehrlich and
colleagues at other institutions have a grim update: the extinction rate is
likely much higher than previously thought and is eroding nature’s ability
to provide vital services to people.
Their new paper, published this week in Proceedings of the National Academy
of Sciences, indicates the wildlife trade and other human impacts have wiped
out hundreds of species and pushed many more to the brink of extinction at
an unprecedented rate.
For perspective, scientists estimate that in the entire twentieth century,
at least 543 land vertebrate species went extinct. Ehrlich and his coauthors
estimate that nearly the same number of species are likely to go extinct in
the next two decades alone.
The trend’s cascading effects include an intensification of human health
threats, such as COVID-19, according to the researchers. “When humanity
exterminates populations and species of other creatures, it is sawing off
the limb on which it is sitting, destroying working parts of our own
life-support system,” said Ehrlich, the Bing Professor of Population
Studies, emeritus, at the Stanford School of Humanities and Sciences and a
senior fellow, emeritus, at the Stanford Woods Institute for the
Environment. “The conservation of endangered species should be elevated to a
national and global emergency for governments and institutions, equal to
climate disruption to which it is linked.”
The study comes in the wake of an April 7 letter from a bipartisan group of
senators urging the Trump administration to close markets that sell live
animals for food and unregulated wildlife markets, among other measures to
stop the trade in illegal wildlife and wildlife products.
Human pressures, such as population growth, habitat destruction, the
wildlife trade, pollution and climate change, critically threaten thousands
of species around the world. Ecosystems ranging from coral reefs and
mangrove forests to jungles and deserts depend on these species’
long-evolved relationships to maintain their functioning and make them
resilient to change. Without this robustness, ecosystems are less and less
able to preserve a stable climate, provide freshwater, pollinate crops and
protect humanity from natural disasters and disease.
Final Opportunity
To better understand the extinction crisis, the researchers looked at the
abundance and distribution of critically endangered species. They found that
515 species of terrestrial vertebrates- 1.7 percent of all the species they
analyzed- are on the brink of extinction, meaning they have fewer than 1,000
individuals remaining. About half of the species studied have fewer than 250
individuals left. Most of the highly endangered species are concentrated in
tropical and subtropical regions that are affected by human encroachment,
according to the study.
In addition to rising extinction rates, the cumulative loss of
populations-individual, localized groups of a particular species- and
geographic range has led to the extinction of more than 237,000 populations
of those 515 species since 1900, according to the researchers’ estimates.
With fewer populations, species are unable to serve their function in an
ecosystem, which can have rippling effects. For example, when overhunting of
sea otters-the main predator of kelp-eating sea urchins-led to kelp die-offs
in the 1700s, the kelp-eating sea cow went extinct.
“What we do to deal with the current extinction crisis in the next two
decades will define the fate of millions of species,” said study lead author
Gerardo Ceballos, a senior researcher at the National Autonomous University
of Mexico’s Institute of Ecology. “We are facing our final opportunity to
ensure that the many services nature provides us do not get irretrievably
sabotaged.”
The loss of endangered creatures could have a domino effect on other
species, according to the researchers. The vast majority-84 percent-of
species with populations under 5,000 live in the same areas as species with
populations under 1,000. This creates the conditions for a chain reaction in
which the extinction of one species destabilizes the ecosystem, putting
other species at higher risk of extinction.
“Extinction breeds extinction,” the study authors write. Because of this
threat, they call for all species with populations under 5,000 to be listed
as critically endangered on the International Union for Conservation of
Nature Red List, an international database used to inform conservation
action on a global scale.
Timely Implications
These findings could aid conservation efforts by highlighting the species
and geographic regions that require the most immediate attention.
Understanding what species are at risk can also help identify what factors
might be most responsible for rising extinction rates.
Among other actions, the researchers propose a global agreement to ban the
trade of wild species. They argue the illegal capture or hunting of wild
animals for food, pets and medicine is a fundamental ongoing threat not only
to species on the brink, but also to human health. COVID-19, which is
thought to have originated in bats and been transmitted to humans through
another creature in a live animal market, is an example of how the wildlife
trade can hurt humans, according to the researchers. They point out that
wild animals have transmitted many other infectious diseases to humans and
domestic animals in recent decades due to habitat encroachment and wildlife
harvesting for food.
“It’s up to us to decide what kind of a world we want to leave to coming
generations-a sustainable one, or a desolate one in which the civilization
we have built disintegrates rather than builds on past successes,” said
study coauthor Peter Raven, president emeritus of the Missouri Botanical
Garden.
The sixth mass extinction of wildlife on Earth is accelerating, according to an analysis by scientists who warn it may be a tipping point for the collapse of civilisation.
More than 500 species of land animals were found to be on the brink of extinction and likely to be lost within 20 years. In comparison, the same number were lost over the whole of the last century. Without the human destruction of nature, even this rate of loss would have taken thousands of years, the scientists said.
The land vertebrates on the verge of extinction, with fewer than 1,000 individuals left, include the Sumatran rhino, the Clarión wren, the Española giant tortoise and the harlequin frog. Historic data was available for 77 of the species and the scientists found these had lost 94% of their populations.
The researchers also warned of a domino effect, with the loss of one species tipping others that depend on it over the edge. “Extinction breeds extinctions,” they said, noting that unlike other environmental problems extinction is irreversible.
Humanity relies on biodiversity for its health and wellbeing, scientists said, with the coronavirus pandemic an extreme example of the dangers of ravaging the natural world. Rising human population, destruction of habitats, the wildlife trade, pollution and the climate crisis must all be urgently tackled, they said.
Human society under urgent threat from loss of Earth’s natural life
Read more
“When humanity exterminates other creatures, it is sawing off the limb on which it is sitting, destroying working parts of our own life-support system,” said Prof Paul Ehrlich, of Stanford University in the US, and one of the research team. “The conservation of endangered species should be elevated to a global emergency for governments and institutions, equal to the climate disruption to which it is linked.”
Harlequin frog. Photograph: Gerardo Ceballos/University of Mexico/PA
“We are facing our final opportunity to ensure that the many services nature provides us do not get irretrievably sabotaged,” said Prof Gerardo Ceballos of the National Autonomous University of Mexico, who led the research.
The analysis, published in the journal Proceedings of the National Academy of Sciences, examined data on 29,400 land vertebrate species compiled by the IUCN Red List of Threatened Species and BirdLife International. The researchers identified 515 species with populations below 1,000 and about half of these had fewer than 250 remaining. Most of these mammals, birds, reptiles and amphibians were found in tropical and subtropical regions.
Scientists discovered that 388 species of land vertebrate had populations under 5,000, and the vast majority (84%) lived in the same regions as the species with populations under 1,000, creating the conditions for a domino effect.
Known examples of this include the overhunting of sea otters, the main predator of kelp-eating sea urchins. A boom in urchins devastated kelp forests in the Bering Sea, leading to the extinction of the kelp-eating Steller’s sea cow.
UN draft plan sets 2030 target to avert Earth’s sixth mass extinction
Read more
The researchers said their findings could aid conservation efforts by highlighting the species and regions requiring the most urgent attention.
Prof Andy Purvis, at the Natural History Museum in London, and not part of the new analysis, said: “This research provides another line of evidence that the biodiversity crisis is accelerating. The hardest problem [the researchers] faced is that we don’t know more about the history of species’ geographic distributions. They only had that information for 77 of the species on the brink, and we can’t know for sure how typical those species are.”
Española giant tortoise. Photograph: Gerardo Ceballos/University of Mexico/PA
“But that doesn’t undermine the conclusion,” he said. “The biodiversity crisis is real and urgent. But – and this is the crucial point – it is not too late. To transition to a sustainable world, we need to tread more lightly on the planet. Until then, we are essentially robbing future generations of their inheritance.”
What is biodiversity and why does it matter to us?
Read more
Prof Georgina Mace, of University College London, said: “This new analysis re-emphasises some startling facts about the extent to which vertebrate populations have been reduced worldwide by human activities.” But she said she was not convinced that simply having a population less than 1,000 was the best measure of a species being on the brink. A declining trend for the population is also important and both factors are used in the IUCN Red List, she said.
“Action is important for many reasons, not least of which is that directly and indirectly we rely on the rest of life on Earth for our own health and wellbeing,” she said. “Disrupting nature leads to costly and often hard-to-reverse effects. Covid-19 is an extreme present-day example, but there are many more.”
Mark Wright, the director of science at WWF, said: “The numbers in this research are shocking. However, there is still hope. If we stop the land-grabbing and devastating deforestation in countries such as Brazil, we can start to bend the curve in biodiversity loss and climate change. But we need global ambition to do that.”
Pythagoras was misunderstood, and Socrates, and Jesus, and Luther, and Copernicus, and Galileo and Newton, and every pure and wise spirit that ever took flesh. To be great is to be misunderstood.~ Ralph Waldo Emerson
I frequently hear and read that COVID-19 is a nefarious attempt by the so-called “elite” among us to depopulate the burgeoning human population on Earth. Other conspiracy theories abound, including COVID-19 as an attempt to further reduce human rights, promote expensive medical therapies, and otherwise enrich the wealthy at the expense of the bamboozled masses.
I do not doubt the ability of the informed wealthy to fleece the ignorant masses. Nor do I doubt the ability of the informed wealthy to turn virtually any situation into an opportunity for monetary gain. A quick glance at the past two centuries provides plenty of examples. However, I doubt the monetarily wealthy among us are interested in accelerating human extinction, even for financial gain. As I explain below, the ongoing reduction in industrial activity as a result of COVID-19 almost certainly leads to loss of habitat for human animals, hence putting us on the fast track to human extinction. I doubt the knowledgeable “elite” are interested in altering the sweet deal they are experiencing with the current set of living arrangements.
In light of the ongoing pandemic, the ongoing Mass Extinction Event, and abrupt, irreversible climate change, I am pleasantly surprised humans still occupy Earth. I strongly suspect the ongoing reduction in industrial activity will reduce the aerosol masking effect sufficiently to trigger a 1 C temperature spike, as described in the peer-reviewed literature. In fact, I suspect it already has. The outcome is not yet obvious because the timing of the outbreak of the novel coronavirus was favorable for human habitat. Trees produced leaves in the Northern Hemisphere spring of 2020 as a result of carbohydrates stored the previous year. Grain crops were harvested before the novel coronavirus emerged. I suspect the results of the recent and ongoing rise in temperature, which has already been reported in China and India, will become obvious to most humans when many more trees die. Large-scale die-off of trees likely will approximately correspond with catastrophic crop failure. This might occur by the end of this year, although I would rather it not.
Every civilization requires bread and circuses. There is little doubt the circuses attendant to industrial civilization will continue until the end of the planetary show for Homo sapiens. Bread, however, requires wheat. Wheat production requires a delicate balance of growing conditions that, like habitat for humans, teeters on the brink. The path to near-term human extinction thus runs from a tiny virus underlying a pandemic through a reduction of industrial activity that overheats a planet already running a fever.
COVID-19 could very well be the event that accelerates human extinction via reduction of industrial activity. If so, the resultant catastrophic meltdown of the world’s nuclear facilities bodes poorly for all life on Earth. As Albert Einstein indicated when he realized his research on particle physics led to the development of nuclear power: “If I had known they were going to do this, I would have become a shoemaker.”
History is replete with examples of human hubris. We thought we were mighty, and we thought we were human, whatever that means. Collectively, we certainly have left our mark on Earth. How embarrassing for the big-brained human species that a microscopic virus could pull the trigger on our extinction. How wonderful for thoughtful individuals that we get to ponder our deaths, and therefore our lives. We get to contemplate not only our lives, but also how we live.
Andrew Glikson does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
in the history of our planet, increasing amounts of carbon dioxide in the atmosphere have caused extreme global warming, prompting the majority of species on Earth to die out.
In the past, these events were triggered by a huge volcanic eruption or asteroid impact. Now, Earth is heading for another mass extinction – and human activity is to blame.
I am an Earth and Paleo-climate scientist and have researched the relationships between asteroid impacts, volcanism, climate changes and mass extinctions of species.
My research suggests the current growth rate of carbon dioxide emissions is faster than those which triggered two previous mass extinctions, including the event that wiped out the dinosaurs.
The world’s gaze may be focused on COVID-19 right now. But the risks to nature from human-made global warming – and the imperative to act – remain clear.
The current rate of CO2 emissions is a major event in the recorded history of Earth.EPA
Past mass extinctions
Many species can adapt to slow, or even moderate, environmental changes. But Earth’s history shows that extreme shifts in the climate can cause many species to become extinct.
For example, about 66 million years ago an asteroid hit Earth. The subsequent smashed rocks and widespread fires released massive amounts of carbon dioxide over about 10,000 years. Global temperatures soared, sea levels rose and oceans became acidic. About 80% of species, including the dinosaurs, were wiped out.
And about 55 million years ago, global temperatures spiked again, over 100,000 years or so. The cause of this event, known as the Paleocene-Eocene Thermal Maximum, is not entirely clear. One theory, known as the “methane burp” hypothesis, posits that a massive volcanic eruption triggered the sudden release of methane from ocean sediments, making oceans more acidic and killing off many species.
So is life on Earth now headed for the same fate?
Comparing greenhouse gas levels
Before industrial times began at the end of the 18th century, carbon dioxide in the atmosphere sat at around 300 parts per million. This means that for every one million molecules of gas in the atmosphere, 300 were carbon dioxide.
Using carbon records stored in fossils and organic matter, I have determined that current carbon emissions constitute an extreme event in the recorded history of Earth.
My research has demonstrated that annual carbon dioxide emissions are now faster than after both the asteroid impact that eradicated the dinosaurs (about 0.18 parts per million CO2 per year), and the thermal maximum 55 million years ago (about 0.11 parts per million CO2 per year).
An asteroid wiped out the dinosaurs 66 million years ago.Shutterstock
The next mass extinction has begun
Current atmospheric concentrations of carbon dioxide are not yet at the levels seen 55 million and 65 million years ago. But the massive influx of carbon dioxide means the climate is changing faster than many plant and animal species can adapt.
A major United Nations report released last year warned around one million animal and plant species were threatened with extinction. Climate change was listed as one of five key drivers.
The report said the distributions of 47% of land-based flightless mammals, and almost 25% of threatened birds, may already have been negatively affected by climate change.
Many researchers fear the climate system is approaching a tipping point – a threshold beyond which rapid and irreversible changes will occur. This will create a cascade of devastating effects.
A shift in climate zones is also causing the tropics to expand and migrate toward the poles, at a rate of about 56 to 111 kilometres per decade. The tracks of tropical and extra-tropical cyclones are likewise shifting toward the poles. Australia is highly vulnerable to this shift.
Uncharted future climate territory
Research released in 2016 showed just what a massive impact humans are having on the planet. It said while the Earth might naturally have entered the next ice age in about 20,000 years’ time, the heating produced by carbon dioxide would result in a period of super-tropical conditions, delaying the next ice age to about 50,000 years from now.
During this period, chaotic high-energy stormy conditions would prevail over much of the Earth. My research suggests humans are likely to survive best in sub-polar regions and sheltered mountain valleys, where cooler conditions would allow flora and fauna to persist.
Earth’s next mass extinction is avoidable – if carbon dioxide emissions are dramatically curbed and we develop and deploy technologies to remove carbon dioxide from the atmosphere. But on the current trajectory, human activity threatens to make large parts of the Earth uninhabitable – a planetary tragedy of our own making.
Scientists have described the serious concept of “Hothouse Earth”.
An international team of researchers suggest that global warming will have severe consequences for the planet.
They paint a picture of boiling hot climates and towering seas in years to come if temperatures rise by just 2C.
That means it could turn some of the planet’s natural forces – that currently protect us – into our enemies.
Dr Sarah Cornell is an environmental scientist and one of the researchers behind the report for the Stockholm Resilience Centre.
She’s described some of the big changes which could happen with a 2C temperature rise – which is the globally accepted amount, according to the Paris climate agreement.
Chocolate is under threat
Image copyrightGETTY IMAGESImage captionCacao pods, from which we get cacao beans for making chocolate, grow in countries around the equator
This is something that is very close to Dr Cornell’s (and everyone else’s) heart.
“Chocolate is just one example of a globally important crop that grows in warm and humid climates,” she says.
But global warming doesn’t mean that there will be more places to grow cacao beans – in fact, it’s the opposite.
A rise in global temperatures causes weather systems to be unpredictable and inconsistent, which would put cacao growing at risk.
“It is about the really intricate pattern of temperature, water flow, light intensity, the nutrients already available in the soil,” says Dr Cornell.
The Arctic could melt
Image copyrightGETTY IMAGES
Ice in the areas around the North Pole could melt completely, says Dr Cornell.
But it’s not just the animals living there which are under threat.
“When you melt the Arctic, you’re changing the way that the whole Earth works,” she says.
“You’re changing ice that reflects heat back into space into dark seawater that absorbs incoming solar radiation.”
So it’s a vicious circle – the less ice there is to reflect heat away from the Earth, the more global warming accelerates.
Image copyrightGETTY IMAGESImage captionThis village in Kiribati, in the Pacific Ocean, had to relocate because of rising sea levels
How can you be a country if you don’t have any land?
Melting ice means rising sea levels – which could put low-lying island nations, such as the Maldives, under the sea.
“It will have all kinds of social consequences because the people who live in these low-lying areas will have to go somewhere,” says Dr Cornell.
“There are already lots of discussions with people in low-lying Pacific islands talking with Australia and New Zealand about where they can live, and how they can have nationhood while renting land from another country.”
Unpredictable rain
Image copyrightEPAImage captionRecent floods in Japan left hundreds of people dead and millions had to evacuate their homes
Combine rising temperatures with other human activity such as deforestation, and you have drastic effects on the water cycle.
“When you change landscapes, you change where water can flow,” says Dr Cornell.
“When you warm the planet and are simultaneously changing the landscape, you’re changing the water cycle… in a much less predictable way than it was before.”
Extreme changes to the water cycle can lead to severe floods – and severe droughts.
How a tree frog affects a whole ecosystem
Image copyrightATLANTA BOTANICAL GARDENImage captionToughie the frog was originally from a forest in Panama
Two years ago, a little brown treefrog called Toughie died in Atlanta, USA, at the age of 12.
He was the last known living Rabbs’ fringe-limbed treefrog to exist.
Toughie’s story is a symbol of the rate of extinction that is being caused as a result of climate change.
The extinction of a species even as small as a frog has consequences which we don’t yet fully understand.
“We could lose treefrogs, and that doesn’t sound important but it’s vitally important because it’s what we lose with it,” says Dr Cornell.
“When we’re killing species, we probably won’t know in advance what the consequences are.
“But we already know that we’re making ecosystems much more vulnerable”.
.png)
Exposing the Big Game 
