The IPCC Fourth Assessment Report is coming out on Feb 2 and we have some leaks about the drafts appearing in The Toronto Star and in Reuters. Just so you know not to trust them, the reports contracdict each other. The Toronto Star reports that projected warming by 2100 will be 2.0-4.5 degrees Celsius, while Reuters gives exactly the same range for climate sensitivity. I doubt that they are both right.
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Ron Bailey makes a dreadful hash of things in this article on the IPCC 4AR. He tries to describe how projections of warming by 2100 have changed as each of the IPCC's four assessment reports has come out. Unfortunately, Bailey confuses warming projections with climate sensitivity (how much…
Now that the new IPCC report has been released it's time to revisit the inaccurate leaks that appeared in The Australian and in The Sunday Telegraph. Both reporters made the same two errors:
they reported the value for climate sensitivity (the eventual warming from doubling CO2) as the IPCC…
The Intergovernmental Panel on Climate Change report is out today, and I was shocked to discover that it is already being misreported. It was being mis-reported before, but that was just leaks. You can lie with leaks. They are easily selective.
Now the mis-reportage is being done with the…
I don't trust the British papers with their various hyperventilating "scoops" about the forthcoming IPCC Fourth Assessment Report. But the Toronto Star just had a story that does sound realistic, reporting on what is purportedly a leaked final draft of the upcoming report's "Summary for…
Well, if it's the sensitivity then we know someone's been reading James Annan, even though they didn't get the paper published.
It seems that the Toronto star is more likely accurate:
"The report estimates that if the amount of carbon dioxide in the atmosphere could be kept below 550 parts per million - which would take a major worldwide effort to cut greenhouse gas emissions - the average global temperature would rise by 2 to 4.5 degrees Celsius above the level before the Industrial Revolution started about 250 years ago."
If CO2 continues at 1.5ppm through the end of the century, the level will stand at about 520ppm by century's end. If it increases at a little faster yearly rate, it is conceivable that it might reach 550ppm by that time (or shortly therafter).
550ppm would be roughly twice the pre-industrial CO2 concentration (about 280ppm), which means the temp rise (2-4.5C) would be in keeping with the sensitivity given by Annan (3C)
On the other hand, it seems that Reuters may have just been sloppy (would not be the first time) when they said
"The draft projects that world temperatures are likely to rise by 2.0-4.5 Celsius (3.6-8.1 Fahrenheit) by 2100 unless the world manages drastic cuts in greenhouse gas emissions from factories, cars and power plants."
Perhaps what they meant to say was "temperatures are likely to rise by 2.0-4.5 Celsius (3.6-8.1 Fahrenheit) by 2100 from pre-industrial levels...", which would have been consistent with what Toronto Star said.
JB, I'm afraid that 1.5 ppm figure is already history, and I'm even more afraid that for all practical purposes 550 ppm is as well. Currently we're over 2 ppm and climbing; see article here. There's a chance that we're seeing the beginnings of the long-feared sink saturation effect. Even without that, the 2.2 ppm average of the last five years would get us to 550 ppm by about 2080.
Yes, I appreciate that, Steve.
But I think it's reasonable to assume that IPCC may have used a value for the yearly CO2 increment (to do their latest projection) that is below the 2 ppm average over the past few years.
I don't question the possibility that the recent increase in the yearly CO2 increment may not be just an anomaly, just that IPCC has accepted it as the norm. I doubt they are yet ready to do that.
Their conservatism in that regard is understandable. Over the past 20 years, there has been a certain amount of scatter in the yearly increment. There were years during the nineties, for example, when it went above 2ppm, only to drop back down (sometimes below the 1.5ppm value).
But I agree that every year that it stays up above 2ppm adds support to the idea that we may be seeing some kind of positive feedback. It may be too soon to conlcude that, however.
JB -
Well, in the 1990s we had both the collapse of the communist bloc - which was a major and inefficient coal burning area - and the 'dash for gas' in a lot of the west. This lead to very subdued CO2 emission increases through the 1990s.
However, the resurgance of Russia and the eastern bloc is leading to increased energy usage and hence CO2 emissions as they recover, and as natural gas prices head for the stratosphere in the western countries a fair few coal plants are emerging from the mothballs. Plus China and India are building coal fired plants like mad.
Furthermore, the relative deficit of high quality crude oil and the replacement with things like heavy oil, tar sands, Gas-To-Liquids and Coal-to-Liquids represents a step increase in CO2 emissions - which would, for example, negate any improvements from a switch to hybrid cars.
So the last few years of high increases are not surprising, and I would expect emissions to be higher than IPCC scenarios for the same economic growth.
Andrew: I suggest you read that article that Steve linked to, because it indicates that emissions alone almost certainly do not account for the recent jump in the yearly "increment" of CO2 (ie, increase in ppm over the prevuious year's value). That increment jumped from an average of just over 1.5ppm in the 90's to 2.1 ppm over the past 5 years.
In other words, total emissions by all the world's countries have not been going up at anywhere near the same steep rate at which the yearly CO2 increment has gone up.
"Over the past few years carbon dioxide has been going up faster than we would expect, based on the rate that emissions are increasing," Prof Cox, Exeter Univeristy.
Re 2007 IPCC Report: when it comes out, we should all compare it against a mainstream scientific sea level rise projection of app. 1 meter or 3 feet by the end of this century (as Science projects this month between 20 to 55 inches), and a high/low temperature increase range of from 4 to 10 degrees (F).
However, given surging chinese CO2 emissions (http://earthtrends.wri.org/updates/node/110), it is likely these ranges will ultimately need to be revised materially upward when they are fully factored in.
If you live near the U.S. coastline and want to see the potential impact of a 3 foot sea level rise on your property, check out ClimateAppraisal.com