The IPCC climate report warns that humans are driving the crisis

The summer was a long series of disasters. A record heat wave killed hundreds of people in the Pacific Northwest and Canada. Extreme floods in Germany killed more than 100 people and left hundreds more missing. Thousands of people have been displaced by the floods in China. Meanwhile, fires are underway all over the world, from California to Greece to Siberia.

Disasters are hitting more frequently and more intensely, just one of the ways the IPCC report says the planet has transformed due to climate change:

  • Global surface temperatures have so far risen by about 1.1 degrees Celsius since the pre-industrial era. This human-induced rate of warming is unprecedented in at least 2,000 years.

  • Heat waves and precipitation events have become more frequent and more intense around the world.

  • The drought is also intensifying.

  • Upper ocean levels have also warmed, ocean acidification has increased, and there has been a decline in Arctic sea ice.

  • Sea heat waves have roughly doubled in frequency since the 1980s.

  • Global sea level has already risen by about half a foot, and sea rise rate is increasing, due to melting glaciers and ocean waters that expand with heat. The rate of sea level rise observed since 1900 is the fastest in at least 3,000 years.

  • And the simultaneous shrinking of so many glaciers globally is unprecedented in at least the last 2,000 years of Earth’s history.

And what’s around the corner if humans don’t stop emitting greenhouse gases into the atmosphere is much worse.

“With each further increase in global warming, the changes in extremes keep getting bigger,” according to the summary report. Extreme heat events, such as heat waves, which occur on average once every 10 years in a world without human-caused climate change, are now likely to occur about 2.8 times in a decade.

And if the planet continues to warm, such deadly events will become even more likely. With 1.5 degrees Celsius of warming, extreme heat waves and other events could occur 4.1 times over a decade, according to the report, while 2 degrees of warming could increase the frequency to 5.6 times. The most alarming scenario, 4 degrees of warming, would have deadly heat events occurring roughly every year.

And it’s not just the extremes of heat. For each additional 0.5 degrees Celsius of warming, the IPCC report warns that there will be an expected increase in the frequency and intensity of heavy rain events, as well as agricultural and ecological drought. Increased warming also brings the growing possibility of simultaneous disasters, such as heat waves and droughts occurring simultaneously.

But as bad as things may go, the report points out that swift and aggressive action on climate change can even reverse some of its effects. A quick effort not only to stop emitting greenhouse gases, but also to extract them from the air, obtaining negative emissions, would stimulate an inversion of surface temperatures and acidification of the surface of the oceans.

Unfortunately, not all climate impacts can be stopped. For example, some global sea level rise is now inevitable. “Sea level change during the mid-century around 2050 was largely blocked,” said summary report co-author Bob Kopp. “Regardless of how quickly we reduce our emissions, we are probably seeing 15 to 30 centimeters, or 6 to 12 inches, of global sea level rise.”

Beyond this point, he added, “sea level projections become increasingly sensitive to the emissions choices we are making today”. Below 2 degrees of warming, sea level will rise by about 1.5 feet by 2100; below 4 degrees, the water level could rise by over 2 feet within this century.

“It is possible to prevent many of the terrible impacts, but it really requires unprecedented transformative change,” said Barrett. “The idea that there is still a way to go, I think, is a point that should give us some hope.”