Science

Earth to Hit Critical Warming Threshold by Early 2030s, Climate Panel Says

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Earth is likely to cross a critical threshold for global warming within the next decade, and nations will need to make an immediate and drastic shift away from fossil fuels to prevent the planet from overheating dangerously beyond that level, according to a major new report released on Monday.

The report, by the Intergovernmental Panel on Climate Change, a body of experts convened by the United Nations, offers the most comprehensive understanding to date of ways in which the planet is changing. It says that global average temperatures are estimated to rise 1.5 degrees Celsius (2.7 degrees Fahrenheit) above preindustrial levels sometime around “the first half of the 2030s,” as humans continue to burn coal, oil and natural gas.

That number holds a special significance in global climate politics: Under the 2015 Paris climate agreement, virtually every nation agreed to “pursue efforts” to hold global warming to 1.5 degrees Celsius. Beyond that point, scientists say, the impacts of catastrophic heat waves, flooding, drought, crop failures and species extinction become significantly harder for humanity to handle.

But Earth has already warmed an average of 1.1 degrees Celsius since the industrial age, and, with global fossil-fuel emissions setting records last year, that goal is quickly slipping out of reach.

There is still one last chance to shift course, the new report says. But it would require industrialized nations to join together immediately to slash greenhouse gases roughly in half by 2030 and then stop adding carbon dioxide to the atmosphere altogether by the early 2050s. If those two steps were taken, the world would have about a 50 percent chance of limiting warming to 1.5 degrees Celsius.

Delays of even a few years would most likely make that goal unattainable, guaranteeing a hotter, more perilous future.

The report comes as the world’s two biggest polluters, China and the United States, continue to approve new fossil fuel projects. Last year, China issued permits for 168 coal-fired power plants of various sizes, according to the Centre for Research on Energy and Clean Air in Finland. Last week, the Biden administration approved an enormous oil drilling project known as Willow that will take place on pristine federal land in Alaska.

The report, which was approved by 195 governments, says that existing and currently planned fossil fuel infrastructure — coal-fired power plants, oil wells, factories, cars and trucks across the globe — will already produce enough carbon dioxide to warm the planet roughly 2 degrees Celsius this century. To keep warming below that level, many of those projects would need to be canceled, retired early or otherwise cleaned up.

“The 1.5 degree limit is achievable, but it will take a quantum leap in climate action,” António Guterres, the United Nations secretary general, said. In response to the report, Mr. Guterres called on countries to stop building new coal plants and to stop approving new oil and gas projects.  

Many scientists have pointed out that surpassing the 1.5 degree threshold will not mean humanity is doomed. But every fraction of a degree of additional warming is expected to increase the severity of dangers that people around the world face, such as water scarcity, malnutrition and deadly heat waves.

The difference between 1.5 degrees of warming and 2 degrees might mean that tens of millions more people worldwide experience life-threatening heat waves, water shortages and coastal flooding. A 1.5-degree world might still have coral reefs and summer Arctic sea ice, while a 2-degree world most likely would not.

“It’s not that if we go past 1.5 degrees everything is lost,” said Joeri Rogelj, director of research at the Grantham Institute for Climate Change and the Environment at Imperial College London. “But there’s clear evidence that 1.5 is better than 1.6, which is better than 1.7, and so on. The point is we need to do everything we can to keep warming as low as possible.”

Scientists say that warming will largely halt once humans stop adding heat-trapping gases to the atmosphere, a concept known as “net zero” emissions. How quickly nations reach net zero will determine how hot the planet ultimately becomes. Under the current policies of national governments, Earth is on pace to heat up by 2.1 to 2.9 degrees Celsius this century, analysts have estimated.

And if temperatures keep rising, many parts of the world may soon face limits in how much they can adapt. Beyond 1.5 degrees Celsius of warming, low-lying island nations and communities that depend on glaciers may face severe freshwater shortages

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