Saturday, October 07, 2006

Bolty sprung

Andrew Bolt, a Right-wing newspaper columnist at the Herald Sun, doesn't like climate change. Not the reality of climate change but the idea itself. Unfortunately, he's not too well read on the subject and relies on skeptic websites such as this, this and this. Reading actual climate science written by climate scientists is just too much work. So, like Chinese whispers, problems creep in when attempting to refer to a scientist’s original work.

In an attempt to debunk Al Gore's movie "An Inconvienent Truth", Bolty misrepresented the work of climate scientist Jeff Severinghaus. Severinghaus found about it and was not too happy. Some of Severinghaus' work showed that there was a rise in the levels of atmospheric CO2 with increasing temperatures in historical episodes of climate change. The bit Bolty jumped at was the time lag, where the initial rising of CO2 levels followed that of rising temperature. His implication was that the rising levels of CO2 had nothing to with warming and Al Gore was in fact lying. Severinghaus, as quoted by, was pissed off.

“Many, many other studies have found that carbon dioxide causes the earth to warm. This is not controversial, and to continue to deny it is akin to denying that cigarette smoking causes cancer,” Severinghaus told Crikey. “The evidence for a human-caused warming of the globe is overwhelming. The scientific debate is over, and what we are seeing now is an attempt to mislead the public.” Severinghaus explained how Bolt had been slippery with the facts, "...Bolt omitted the key piece of information that the warmings took 5,000 years, thus misleading the reader into thinking that carbon dioxide was not warming at the same time as temperature and thus cannot have caused the warming...”

Severinghaus wrote a letter to the editor of the Sunday Mail, but it was never published. He posted a comment on Bolt’s blog but told Crikey “...effectively I have not been able to make much if any response”.

“At the very least I would like it to go on record that Bolt's abuse of my science is not done with my approval,” says Severinghaus.

So is the professor sick of having his research misrepresented in the press? “My research actually mostly isn't misrepresented,” he told Crikey. “But it is sometimes misrepresented on climate-denialist websites. I suspect, though do not know, that Bolt got the info from a climate-denialists website.”

So what did Bolty do? He tried to wing it and failed oh so badly. When I pulled him up on it in yesterday’s cesspit he screeched:

Severinghaus' research shows CO2 levels have tended to rise AFTER the globe's temperature starts to rise - and some 5000 years afterwards at that, which is what I drew attention to. This clearly suggests, as he and others have acknowledged, that the warming at least initially may not be caused by increased CO2, but in fact cause it. Severinghaus claims there is a later feedback mechanism so that the increased CO2 in turn increases the warming (many hundreds of years later), but this does not at all dispute the point I made - especially since the warming we've seen has occurred for less than 150 years. So what caused that initial warming in those previous warming episodes, and in this? Yes, he's still a man-made global warming believer, and is upset that I draw attention to this curious fact he's helped to discover, but bad luck to him. His rage and spluttering should not be allowed to obscure the central fact - that Al Gore shows slides from previous ice age that contrary to what he suggests in fact show increased CO2 concentrations initially FOLLOWING rising temperatures (by perhaps as much as 5000 years, say some researchers) and not before. (I've added a couple of words to my initial response to emphasise obvious points that later gotcha-hopers have failed to note, and will probably continue to.) For more on this and links to yet more, see
Check for yourself, and deal with the facts.

But poor old Bolty hadn't actually read Severinghaus' research. Severinghaus stated that the total period of warming was 5000 years while the lag was 800 years.

Does this prove that CO2 doesn't cause global warming? The answer is no.

The reason has to do with the fact that the warmings take about 5000 years to be complete. The lag is only 800 years. All that the lag shows is that CO2 did not cause the first 800 years of warming, out of the 5000 year trend. The other 4200 years of warming could in fact have been caused by CO2, as far as we can tell from this ice core data.

The 4200 years of warming make up about 5/6 of the total warming. So CO2 could have caused the last 5/6 of the warming, but could not have caused the first 1/6 of the warming.
It comes as no surprise that other factors besides CO2 affect climate. Changes in the amount of summer sunshine, due to changes in the Earth's orbit around the sun that happen every 21,000 years, have long been known to affect the comings and goings of ice ages. Atlantic Ocean circulation slowdowns are thought to warm Antarctica, also.

From studying all the available data (not just ice cores), the probable sequence of events at a termination goes something like this. Some (currently unknown) process causes Antarctica and the surrounding ocean to warm. This process also causes CO2 to start rising, about 800 years later. Then CO2 further warms the whole planet, because of its heat-trapping properties. This leads to even further CO2 release. So CO2 during ice ages should be thought of as a "feedback", much like the feedback that results from putting a microphone too near to a loudspeaker.

After I pointed out to Bolty the error of his ways he refused to change his posting to reflect what Severinghaus had actually said, not what he'd hoped he said.

The man’s credibility on this subject is already pretty low. Here's hoping after this episode it's that bit lower.

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