Humans have pushed the #climate into ‘unprecedented’ territory, landmark U.N. report finds — The Washington Post

From The Washington Post (Brady Dennis and Sarah Kaplan):

U.N. chief calls findings ‘a code red for humanity’ with worse climate impacts to come unless greenhouse gas pollution falls dramatically

More than three decades ago, a collection of scientists assembled by the United Nations first warned that humans were fueling a dangerous greenhouse effect and that if the world didn’t act collectively and deliberately to slow Earth’s warming, there could be “profound consequences” for people and nature alike.

The scientists were right.

On Monday, that same body — the Intergovernmental Panel on Climate Change — described how humans have altered the environment at an “unprecedented” pace and detailed how catastrophic impacts lie ahead unless the world rapidly and dramatically cuts greenhouse gas reductions.

The landmark report states that there is no remaining scientific doubt that humans are fueling climate change. That much is “unequivocal.” The only real uncertainty that remains, its authors say, is whether the world can muster the will to stave off a darker future than the one it already has carved in stone.

The sprawling assessment, compiled by 234 authors relying on more than 14,000 studies from around the globe, bluntly lays out for policymakers and the public the most up-to-date understanding of the physical science on climate change. Released amid a summer of deadly fires, floods and heat waves, it arrives less than three months before a critical summit this November in Scotland, where world leaders face mounting pressure to move more urgently to slow the Earth’s warming.

U.N. Secretary General António Guterres called the findings “a code red for humanity” and said societies must find ways to embrace the transformational changes necessary to limit warming as much as possible. “We owe this to the entire human family,” he said in a statement. “There is no time for delay and no room for excuses.”

But so far, the collective effort to slow climate change has proved gravely insufficient. Instead of the sort of emission cuts that scientists say must happen, global greenhouse gas pollution is still growing. Countries have failed to meet the targets they set under the 2015 Paris climate accord, and even the bolder pledges some nations recently have embraced still leave the world on a perilous path.

“What the world requires now is real action,” John F. Kerry, the Biden administration’s special envoy for climate, said in a statement about Monday’s findings. “We can get to the low carbon economy we urgently need, but time is not on our side.”

It certainly is not, according to Monday’s report.

Humans can unleash less than 500 additional gigatons of carbon dioxide — the equivalent of about 10 years of current global emissions — to have an even chance of limiting warming to 1.5 degrees Celsius (2.7 Fahrenheit) above preindustrial levels.

But hopes for remaining below that threshold — the most ambitious goal outlined in the Paris agreement — are undeniably slipping away. The world has already warmed more than 1 degree Celsius (1.8 degrees Fahrenheit), with few signs of slowing, and could pass the 1.5-degree mark early in the 2030s.

“Unless we make immediate, rapid and large-scale reductions in greenhouse gas emissions, limiting warming to 1.5C will be beyond reach,” said Ko Barrett, vice chair of the IPCC and senior adviser for climate at the National Oceanic and Atmospheric Administration. “Each bit of warming will intensify the impacts we are likely to see.”

Already, we are living on a changed and changing planet.

Each of the past four decades has been successively warmer than any that preceded it, dating to 1850. Humans have warmed the climate at a rate unparalleled since before the fall of the Roman Empire. To find a time when the level of carbon dioxide in the atmosphere changed this much this fast, you’d need to rewind 66 million years to the end of the age of the dinosaurs.

Carbon dioxide in the atmosphere has risen to levels not seen in 2 million years, the authors state. The oceans are turning acidic. Sea levels continue to rise. Arctic ice is disintegrating. Weather-related disasters are growing more extreme and affecting every region of the world.