5 signs of how climate change is unraveling Earth’s ecosystems

Global warming is taking a bigger toll on wildlife than we previously thought, a new IPCC report shows.

Coral reefs are especially vulnerable to rising temperatures. Here, corals suffer from “bleaching” in Australia’s Great Barrier Reef. |Getty Images 

By now, many symptoms of climate change, from heat-fueled superstorms to rising sea levels, are impossible to ignore. But there’s another, less-visible consequence of global warming that is just as disturbing: the staggering loss of plants and animals and the countless benefits they provide.

In a new report from the UN’s Intergovernmental Panel on Climate Change (IPCC), researchers from 67 countries warned that warming is putting a large portion of the world’s biodiversity and ecosystems at risk of extinction, even under relatively conservative estimates. Never before has an IPCC report — considered the gold standard for climate science — revealed in such stark detail how climate change is harming nature.

What ails wildlife ails us, the authors wrote. Humans are inextricably dependent on many species that are in jeopardy from rising temperatures, whether they’re animals that pollinate crops, filter rivers and streams, or feed us. In the US alone, for example, more than 150 crops depend on pollinators, including nearly all fruits and grains, and climate change puts them at risk.

Humans have warmed the planet by an average of 1.1 degrees Celsius (2 degrees Fahrenheit) since the 19th century. While the landmark Paris agreement aims to limit warming to 1.5 to 2 degrees Celsius, global temperatures are on track to grow to between 2 and 3 degrees C by the end of the century.

The IPCC’s lengthy report is packed with evidence of how rising temperatures are putting biodiversity and ecosystems at risk — but the following five figures stand out. Each is a reminder of what we have to lose and how much we can gain if governments and companies dramatically cut their carbon emissions.

14 percent of all species living on land are at risk of going extinct

If the planet warms by 1.5 degrees Celsius — which is almost certain — up to 14 percent of all plants and animals on land will likely face a high risk of extinction, according to the report. The outlook becomes graver if temperatures rise even further; with 3 degrees of warming, for example, up to 29 percent of species on land could face extinction.

In the next few decades, some plants and animals will likely experience temperatures “beyond their historical experience,” especially those that live in polar regions, the authors wrote. Even 1.2 degrees Celsius of warming — just above current levels — puts many ecosystems at risk from heatwaves, drought, and other climate extremes, they added.

Climate change is likely to take a greater toll on animals that are found only in one location, known as endemic species.

47 percent of species have already lost some of their populations due to climate change

Global warming has already extinguished local populations of many creatures — roughly half of the 976 species that one researcher studied in 2016. The American pika, for example, has disappeared from a large swath of its former habitat in the Sierra Nevada mountains in California, likely due to climate change, according to a 2017 study. Adapted to cool weather, these small mammals are especially vulnerable to unusually warm weather.

An American pika with a mouthful of grass. Arterra/Universal Images Group via Getty Images

In 2005, heatwaves decimated a subspecies of lemuroid ringtail possum, a rare marsupial, in Queensland, Australia, according to the report. And rising seas and storm surges were likely behind the recent extinction of an Australian rodent called the Bramble Cay melomys.

Just last summer, scorching temperatures killed hundreds of millions of marine animals in the Pacific Northwest, from sea stars to mussels. They also threatened millions of young salmon — fish with intricate and important ties to Indigenous tribes. These kinds of species losses are worse in the tropics and in freshwater ecosystems, the authors write.

Half of all species have moved toward the poles or up mountains

Climate change is also reorganizing entire ecosystems. To escape deadly temperatures, plants and animals are moving to (once) colder climates — that is, toward the poles, up mountainsides, or into deeper water.

Roughly half of all species studied have moved toward the poles or to a higher elevation, according to the report. Those shifts are especially noticeable at sea, where they’ve traveled on average 59 kilometers (37 miles) per decade poleward, according to the report. Large numbers of Atlantic mackerel, for example, have moved from waters near the UK and Scandinavia to Iceland, spurring geopolitical tensions related to fishing rights.

The warming climate is changing animals in other ways, too. A large number of studies, for example, suggests that it’s making many species smaller.

Coral reefs could decline by 90 percent

Climate scientists have an especially grim prognosis for coral reefs: Just 1.5 degrees Celsius of warming could destroy up to 90 percent of tropical coral reefs, which are home to an incredible diversity of organisms and form the basis of many fisheries.

Global warming hits reefs with a double-punch. Oceans absorb a third or more of the carbon dioxide that enters the atmosphere, which makes them more acidic over time. That’s bad news for reefs — as is unusually warm water. Rising ocean temperatures can cause coral to eject the algae that live harmoniously with them, in a process known as bleaching. Bleached coral is more likely to die.

“Almost all coral reefs will degrade from their current state, even if global warming remains below 2 degrees C,” the researchers wrote. “Their global decline shows that we don’t need to look into the future to recognize the urgency of climate action.”

Climate change will make 8 percent of the world’s farmland “unsuitable” by 2100

The impact of climate change on food production is equally troubling. According to the report, just 1.6 degrees C of warming this century will make 8 percent of today’s farmland “climatically unsuitable.” And by 2100, there will be more, not fewer, mouths to feed globally.

The decline of fish caused by climate change also puts food security at risk, because so many coastal communities worldwide depend on fisheries. Scientists project that in tropical Africa, people will lose up to 41 percent of their fisheries’ yield by the end of the century “due to local extinctions of marine fish,” under 1.6 degrees Celsius of warming. “Declining fish harvests could leave millions of people vulnerable to malnutrition,” the authors wrote.

Climate change is also threatening varieties of coffee, chocolate, and other foods we love.

How to slow the extinction crisis

Later this year, government officials from around the world will meet to hammer out a global deal to prevent the loss of biodiversity. The deal — which is part of an international treaty called the Convention on Biological Diversity — is likely to include a commitment to conserve at least 30 percent of all land and seas by 2030.

According to the IPCC authors, reaching that target would make ecosystems healthier and offset much of the damage that climate change is causing. “Healthy ecosystems are more resilient to climate change and provide life-critical services such as food and clean water,” said Hans-Otto Pörtner, who co-chairs IPCC’s Working Group II, which published the report.

But ultimately, to protect nature, companies and governments — and, to a lesser extent, individuals — will have to reduce their emissions, and fast. “Any further delay in concerted global action,” Pörtner said, “will miss a brief and rapidly closing window to secure a livable future.”


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