It has been eight years since the last major report from the Intergovernmental Panel on Climate Change (IPCC), though it has produced smaller reports since then. But today, the first piece of the 6th Assessment Report is out. Most of it should not surprise you—the basics of climate science have been known for decades. And the general outlines were already obvious: almost all of the warming is due to human activities, and, without immediate action, we’re poised to blow past 1.5º C of warming.
Still, each report is a little more useful than the last, and we’re going to go over what has changed in terms of the science and what has changed in how that information is being shared with the public.
Today’s release is the Working Group I section of the report. It’s massive — a product of 751 scientists that references over 14,000 studies and data sources…Using the average of the last decade, the report notes that surface temperatures have warmed about 1.09°C (1.96°F) since the late 1800s. The new summary statement about humanity’s contribution to that warming says, “The likely range of total human-caused global surface temperature increase from 1850–1900 to 2010–2019 is 0.8°C to 1.3°C, with a best estimate of 1.07°C.” That is, humans are responsible for approximately all of it.
Putting this into historical context, the report concludes that the present state of the climate goes beyond anything the Earth has seen in quite some time: “In 2019, atmospheric CO2 concentrations were higher than at any time in at least 2 million years[…] Global surface temperature has increased faster since 1970 than in any other 50-year period over at least the last 2,000 years.”
Finally, projections of various future greenhouse gas concentrations highlight the futures we can yet choose between. It is still physically possible to limit warming to 1.5° C or 2° C, given the will to act. It is likewise still possible to cross 4° C or 5° C by 2100, given a sufficiently blatant disregard for current and future life on our planet.
So, what’s the heritage we leave for future generations. People who can afford the best, newest and (probably) most expensive will do OK. The rest of your family in the coming era will be cursed by our inaction…or grateful if we get off our rusty dustys and do something useful to halt and eventually reverse the trend. Scientists are actively pursuing guidelines. A number of educated politicians and activists are trying to provide leadership.
And the rest, a predictable lot, will wallow in the ethos of doing nothing or aiding the Know-Nothings of this century.