Posted on August 10, 2021 by Seth Jaffe
The IPCC has released its Sixth Assessment Report on the physical science basis of climate change. I would say that it makes sobering reading, except any sane person’s immediate response to AR6 would be to go out and have any number of stiff drinks. Here are a number of the lowlights:
It is unequivocal that human influence has warmed the atmosphere, ocean and land. Widespread and rapid changes in the atmosphere, ocean, cryosphere and biosphere have occurred.
Global surface temperature has increased faster since 1970 than in any other 50-year period over at least the last 2000 years.
Human-induced climate change is already affecting many weather and climate extremes in every region across the globe.
Global surface temperature will continue to increase until at least the mid-century under all emissions scenarios considered. Global warming of 1.5°C and 2°C will be exceeded during the 21st century unless deep reductions in CO2 and other greenhouse gas emissions occur in the coming decades.
Many changes due to past and future greenhouse gas emissions are irreversible for centuries to millennia, especially changes in the ocean, ice sheets and global sea level.
In the longer term, sea level is committed to rise for centuries to millennia due to continuing deep ocean warming and ice sheet melt, and will remain elevated for thousands of years. (My emphasis.)
Here are my key takeaways from the IPCC:
- Over time, all of the uncertainties in climate science have resolved towards greater certainty of more significant impacts. It’s time for the skeptics to stop pointing to uncertainty as an argument against aggressive action.
- On a more mundane point, I agree with Mike Gerrard (subscription required) that the IPCC now provides sufficient evidence of attribution to have real potential to impact climate change litigation.
- The increasing pace of climate change might give climate change hawks some well-deserved schadenfreude, since now skeptics will still be alive when the proof is delivered that climate change is real – if it weren’t such an utter disaster for everyone.
- And finally – the scope of the disaster cannot result in paralysis. Back to one of my favorite texts:
“It is not your responsibility to finish the work of perfecting the world, but you are not free to desist from it either.”