Global climate change is accelerating and human-caused emissions of greenhouse gases are the overwhelming cause, according to a landmark report released Monday by the United Nations. There is still time to avoid catastrophic warming this century, but only if countries around the world stop burning fossil fuels as quickly as possible, the authors warn.
The message to world leaders is more dire, and more unequivocal, than ever before.
"It is indisputable that human activities are causing climate change," says Ko Barrett, the vice chair of the U.N. Intergovernmental Panel on Climate Change (IPCC) and the senior adviser for climate at the U.S. National Oceanic and Atmospheric Administration. "Each of the last four decades has been the warmest on record since preindustrial times."
The authors — nearly 200 leading climate scientists — hope the report's findings will be front and center when world leaders meet for a major climate conference in November.
The effects of that warming are obvious and deadly around the world. Heat waves, droughts and floods are killing people and disrupting lives around the world this summer. Wildfires are burning with unprecedented frequency and intensity, including in places that used to rarely burn. Smoke and smog are choking people in cities and towns from Asia to the Arctic. Ocean heat waves are threatening entire ecosystems and supercharging hurricanes and typhoons.