Because of the enormous credibility of the Intergovernmental Panel on Climate Change's reports, and because they suggest that human-induced climate change is a very real risk, opponents of action on climate change must attack the IPCC or completely cede the scientific high ground in the debate.
With the release of the latest IPCC report, a whole new crop of specious skeptical arguments has arisen. Here's a good example, which appeared in this week's Weekly Standard:
One possible reason for the timing is that there appear to be some significant retreats from the 2001 IPCC report. The IPCC has actually lowered its estimate of the magnitude of human influence on warming, though we shall have to wait for the full report in May to understand how and why. Only readers with detailed knowledge of the 2001 report would notice these changes, which is why most news accounts failed to report them.
As with most skeptical arguments, there is a grain of truth here, sitting under a mountain of deception.
The truth is that the IPCC did indeed lower its estimate of radiative forcing of the planet due to humans from 2.4 to 1.6 watts per square meter. Radiative forcing is the change in downward infrared flux caused by human activities, and it is a standard measure of how humans have impacted the climate system.
The reason for this revision is not that we think CO2 and other well-mixed greenhouse gases are less effective at warming. Rather, we have learned that tiny particles suspended in the atmosphere, known as aerosols, are reflecting sunlight back to space. The cooling associated with this reduction of sunlight has been offsetting some of the heat trapped by CO2.
Aerosols are a primary component of air pollution, and breathing them has significant negative health effects. Many of their sources are activities found in the developing world, where air quality regulations are lax or non-existent. As these places get serious about reducing air pollution, emissions of aerosols will decrease.
This, in turn, will decrease the aerosol burden in the atmosphere. That's because aerosols only stay in the atmosphere for a few days or weeks -- compared to CO2's lifetime of a century or two -- so a decrease in aerosol emission is followed relatively rapidly by a decrease in atmospheric concentration.
As the abundance of aerosols in the atmosphere decreases, its offsetting effects on CO2 will also decrease. Our climate will then be exposed to the full climatic effects of CO2.
That will result in additional warming.
In other words, the IPCC's 2007 revision in radiative forcing doesn't mean climate change is less serious than previously thought; on the contrary, it means there is warming in the pipeline we have yet to experience.
This argument, like its forebears, is cleverly constructed to mislead.
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Comments
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Benny Big Eye Posted 6:14 am
11 Feb 2007
Second, you gotta love the victimology of current skeptics. From the Weekly Standard: "The rollout of the IPCC report and the Guardian story attacking us coincide with the climax of what can be aptly described as a climate inquisition intended to stifle debate about climate science and policy. Anyone who does not sign up 100 percent behind the catastrophic scenario is deemed a "climate change denier."
Well, that's not true, because Roger Pielke Jr. has been taking calls left and right from the press and was even invited to give congressional testimony from the Republicans.
Benny Big Eye
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sunflower Posted 6:26 am
11 Feb 2007
The next battlefield will be "solutions" policy. The AEI may find new funding for that battle. Where does the funding come from (more than $160 million the last seven years)?
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Zarkov Posted 10:45 am
11 Feb 2007
The main technique to quell open discussion is silence.
If there was nothing to hide, why the silence?????
Surely an open debate addressing the causes of Global Climate Change is of world importance, or is there something more important that this world......
Mad people would say here and now is more important that tomorrow, and that money and lifestyle must not be assailed even if this attitude leads to the total destruction of civilisation.....
If a dissenter has something to say, then science can cope with that, so really there is nothing to fear with the science, it is the mad people and their hidden agendas and their precious egos that wish to silence dissent.
We all fought hard to counter this trait in dominating human beings, but now apathy and effluent affluence has made we just can't be bothered.
LOL y'all are complicit, but y'all will have to pay the piper the day after tomorrow, which is not very far off.
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Steve Bloom Posted 12:48 pm
11 Feb 2007
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Andrew Dessler Posted 1:41 pm
11 Feb 2007
I'm not sure what 0.5°C lag Hansen's talking about. When most people talk about lag in the climate system, they are talking about thermal lag caused by the oceans. This aerosol effect would be an additional warming that would occur after developing countries clean up their air.
Thanks!
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Zarkov Posted 2:25 pm
11 Feb 2007
That trapped heat has massive potential to disrupt civilisation, because the ocean heat must be lost via evaporation (whenever that can occur) and the result of that process is cloud banks.
It is the cloud banks that deliver the ice and snow for an Ice Age to occur. Heat drives an Ice Age, not cold.
Tis somewhat interesting that AD, a climate scientist remains silent....... something to hide Andrew?
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Zarkov Posted 8:01 am
12 Feb 2007
Indeed and all the other so called environmental blogs are all set up by Big Oil it would appear.
You the readers, are being hoodwinked into believing their insipid crap. They tell you greenhouse gases are your fault, no! they are Big Oil's fault.
They have turned your head away from the real problems and made you run scared.
And the blog organisers, here, real climate and many others are just spreading propaganda sanctioned by Big Oil.
If this is not true, why the censorship, and why the lack of meaningful discussion and why the head in the sand attitude.
All the so called research is based upon the Northern Hemisphere, and it is all corrupted by inadequate computer programmed projections.
>>> Two of Greenland's largest glaciers shrank dramatically and dumped twice as much ice into the sea during a period of less than a year between 2004 and 2005. And then, less than two years later, they returned to near their previous rates of discharge. >>> University of Washington
Sadly you guys are falling for it.
Oil is the problem and yes the oil companies must suffer.
Would you rather Them or You.
Remember the owners of this Earth are the children, and you never think of them do you.
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Lockforward Posted 1:28 am
13 Feb 2007
Sea Level
In the 2001 IPCC, the range given for the projected sea-level rise was 8 to 99 cm ( http://www.ipcc.ch/pub/spm22-01.pdf) (see p. 16). In ... (see p. 13) . As I'm sure you know, 59 cm =23.2 in., less than two feet, and not even 10% of the 20 ft. scare tactic Mr. Gore employed in "An Inconvenient Truth". Following the release of the report, the relevant government agencies in Netherlands, along with the Maldives the lowest - lying nation on earth, have concluded that the country can accomodate not only the upper end of the IPCC sea level range, but also an increase of 1 meter per century with the nation's "existing techniques and the current level of expenditure on coastal protection".
http://www.expatica.com/actual/article.asp?subchannel_id= ...
Incidentally, the sea level rose about 20 cm in the 1900s, and a much less technologically advanced human society than the one we will see in the 21st century handled that increase pretty much without skipping a beat.
http://en.wikipedia.org/wiki/Sea_level_rise#_note-0
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Lockforward Posted 1:32 am
13 Feb 2007
In 2007, the range has been tightened to 18 to 59 cm (http://www.ipcc.ch/SPM2feb07.pdf) (see p. 13)
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amazingdrx Posted 1:48 am
13 Feb 2007
Anyway, catch the "Colbert Report" rerun today. Colbert goes through all the objections to the IPCC and even invents a couple more. Excellent!
http://amazngdrx.blogharbor.com/blog
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Lockforward Posted 1:48 am
13 Feb 2007
2007 IPCC - 1.8 C - 4.0 C
http://www.ipcc.ch/SPM2feb07.pdf
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Andrew Dessler Posted 4:26 am
13 Feb 2007
First, the Weekly Standard article clearly refers to man's impact on warming, which my post addresses and shows is simply wrong. If they were referring to sea level, I assume they would have said sea level.
The 2007 IPCC temperature estimates are presented in a completely different format than the TAR's. The numbers you quoted, 1.4-4, is the range of "best estimates" of the six scenarios. If you include the "likely" range of each scenario, the upper end extends to over 6 deg C. Pretty similar to the 2001 report, which did not explicitly break out "best estimates" from "likely".
As far as sea level goes, I view the 2001 and 2007 reports as roughly similar. The 2001 IPCC did not give a "best estimate", but if they did it would probably lie within the 2007 range. And considering the uncertainties, including known processes not included in the models, there is actually great consistency in the results.
Regards
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Lockforward Posted 7:07 am
13 Feb 2007
On closer examination, I think you are right about temp, but not sea level. Look at chart 5d on p.14 in the TAR. The outer perimeters of each seem to be the extreme ends of the models, and thus a closer statistical match to range and not the best estimate numbers in the 2007 report.
Likewise, 5e, dealing with sea level, is in the same format, and yields the 8 to 99 cm. range. As you note, the 2007 IPCC gives no best estimate of the models, only their range, and thus the 2007 18-59cm range seems to be the statistical twin of the 2001 8-99 cm range. That a "best estimate" range would take that upper end even lower than 59 cm is even more encouraging, though such a range would not be comparable to the 2001 range.
So, while I'm encouraged by the lowering of the best estimate range for temps, your point is well taken. It does appear, however, that a substantial downward revision has occured for projected sea level increases.
What do you think?
Regards,
Bill
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Andrew Dessler Posted 2:37 pm
13 Feb 2007
Thus, we know sea level rise will very likely not be 5 cm and it very likely will not be 5 meters, but within the 10 cm to 100 cm, we really just don't know. That's my interpretation, anyway.
Thanks for your comments.
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cce Posted 5:50 pm
16 Feb 2007
It also does not "abandon" the "Hockey Stick." Quite the opposite, since it makes an even stronger statement. "Paleoclimate information supports the interpretation that the warmth of the last half century is unusual in at least the previous 1300 years" (page 10).
The sea level rise depicted in Gore's movie would be the inevitable result of the breakup of Greenland or West Antartica, which would take some time. The sea level estimates are for this century only. If there exists a tipping point, little to nothing we do could reverse this once underway.
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