Assessing the size and uncertainty of remaining carbon budgets | Research Squarehttps://www.researchsquare.com/article/rs-1934427/v1https://twitter.com/RobinLamboll/status/1566773538920443905?s=19If we take 280 ppm as the pre-industrial CO2 level and 3 ºC as the climate sensitivity, we see that 350 ppm would be just below +1.0 ºC.
For a climate sensitivity of 6 ºC, all of the numbers DOUBLE in the temperature column above. Thus 350 ppm causes +2.0 ºC of heating. For whom is that safe? Two degrees is not safe for Africa, the Amazon, and especially not for low-lying island nations.
Two degrees is probably a safe limit for the civilization of Western capitalism – the real "stakeholders" at COP meetings. But as shown on the chart, the CO2 level that will ensure such warming was reached way back in May 1986 !!
By April 2012 there was enough CO2 in the atmosphere to cause +3.0 ºC. That's enough heating for no ice in the Arctic, Greenland or West Antarctica, no coral reefs, no Amazon, scarce food crops – and probably no civilization. At 420 ppm we are today assured of +3.5 ºC.
The premise of today's obscene "carbon budgets" is a target of +2.0 ºC heating, while using a short-term climate sensitivity of only 3 ºC. That would explain the plutocratic hubris to drive the planet up to 450 ppm. It's short-term physics for short-term profiteers.
We are now collectively starring into the abyss of decimated ice albedo and crashing biological systems that turn sinks into sources. Skies are red, the Arctic is blue, and fields are brown.
Methane seems to be pouring into the atmosphere so fast that we can barely keep track of its sources.
These inevitable feedbacks and paleoclimate research tell us the same thing, over and over: Climate sensitivity is much higher. 450 ppm will give us +4.0 ºC instead.