More PlayStation® climatological horse spit. What most people don’t realize is that IPCC documentation explicitly shows CO2‘s ability to increase greenhouse effect is rapidly exhausting.
Doubling CO2 does not double its effect or anything close to that, it’s logarithmic.
What does that mean?
Actually it’s easy:
Taking pre-Industrial Revolution levels of 280 parts per million as an example, the first half of CO2‘s greenhouse effect was delivered not by 280/2 or 140 ppm but √280 or just under 17 ppm.
To double pre-IR’s CO2 greenhouse effect would take not 4 times 17 or even 2 times 280 = 560 but 280 squared or 78,400 ppm.
CO2‘s additional effect collapses quickly, doesn’t it.
Naturally the IPCC does not try to make it so plain and they use delta forcing (ΔF) = αLN(C/Co).
Translation: the constant α is 5.35 and you times that by the natural log of the current amount of CO2/original CO2 so 2 times CO2 = 5.35LN(2/1) for every doubling.
In real terms that’s 3.7 Watts per meter squared added forcing for each doubling of CO2 regardless of whether that’s from 100 to 200 ppm or 1,000 to 2,000 ppm.
But what is that in actual temperature increase?
We’re glad you asked because we have already showed how Trenberth’s global mean energy budget, which already includes earth’s water vapor feedback, cloud effects and what have you in the back radiation figure, shows that a doubling of CO2 adds just 0.37 °C to earth’s mean temperature. See it explained here, with pretty color graphics too.
That’s why we can confidently state the UK Press Association’s following piece is just more PlayStation® climatological horse spit:
Even moderate emissions could warm the Earth by as much as 3C by 2050, leaders of a huge climate simulation project have warned.
Scientists who harnessed the power of thousands of volunteers’ home computers forecast a faster rate of warming than has been predicted before.
The models showed that average world temperatures are on course to rise by between 1.4C and 3C given mid-range greenhouse gas emissions.
According to the findings, the world is very likely to cross the critical “two degrees barrier” at some point this century if emissions continue unabated.
Experts believe warming of 2C above pre-industrial levels could trigger runaway climate change that cannot be reversed.
Almost 10,000 climate simulations were run using volunteers’ home computers. The project, climateprediction.net, was part of the BBC Climate Change Experiment.
Scientists selected the most realistic projections after comparing them with regional temperature changes over the past 50 years. None passing the quality control test showed less than 1C warming by 2050. But a surprisingly high fraction of simulations, around 15%, predicted warming by as much as 3C.
The authors concluded that a 3C rise by 2050, compared with the average for 1960 to 1990, marked the upper end of the “likely range” of global warming. The research is published in the journal Nature Geoscience.
Lead author Dr Dan Rowlands, from Oxford University’s Department of Physics, said: “It’s only by running such a large number of simulations – with model versions deliberately chosen to display a range of behaviour – that you can get a handle on the uncertainty present in a complex system such as our climate.
“Our work was only possible because thousands of people donated their home computer time to run these simulations.”