Mankind has had less effect on global warming than previously supposed, a United Nations report on climate change will claim next year.With the fourth report of the UN's Intergovernmental Panel on Climate Change (IPCC) about to be released early next year, jostling for position has already been taking place to spin the report. Just a couple of days ago, for example, we had this from Yahoo News: "the phone-book-sized report will convey an unvarnished message that will be bleak and quite possibly terrifying. Those close to the IPCC say it will not only confirm the grim warnings of the past but also amplify them."
Well, maybe not. Mongabay summarises the forthcoming Policy-makers' Summary of IPCC IV:
The Telegraph says that the report will reduce its estimate of man's role in global warming by 25 percent. However, the IPCC will still project global temperatures to climb by [up to] 4.5 C during the next century and rising sea levels, albeit by half the amount -- 17 inches instead of 34 inches by 2100 -- forecast by the IPCC's 2001 report. It will also note that atmospheric carbon dioxide levels have continued to climb over the past five years [See Not PC: More Restrictions, Less Power, More Carbon] but that the overall human effect on global warming since the industrial revolution has been dampened by cooling caused by particulate matter and aerosol sprays, which accumulate in the upper atmosphere and reflect heat from the sun.There is no more persuasive or more widely-reported document in the global warming debate than the reports produced by the IPCC -- or, to be perfectly accurate, the Policy-makers' Summaries of the IPCC reports. Indeed, it was the predictions made in the first IPCC report in 1990 that kicked off the current hysteria, even though sixteen years later their predictions of global-warming-generated disaster have largely failed to materialise. (The Policy-makers Summary for the 1990 report predicted a 0.3 C-per-decade rise in global mean temperature due to what it called an "enhanced greenhouse effect," and a whopping six-centimetre-per-decade rise in the average sea level. In fact temperatures have been falling since a 1988 El-Nino high, and sea level rises have persistently refused to accelerate as predicted, remaining at just 2.4 ± 1.0 mm/year.)
In the absence of significant, real planet-wide warming or of any sea-level rises to report anywhere near that magnitude, it is computer models and myths upon which scaremongers have to rely for their evidence of warming, and it is the Policy-makers' Summaries of IPCC reports on which the media relies for their own reports, even though these summaries themselves have been widely criticised for being misleading and unrepresentative (British scientist Keith Shine for example: "We produce a draft, and then the policy-makers go through it line by line and change the way it is presented.... It's peculiar that they have the final say in what goes into a scientists' report" ).
Astute readers will have noticed that each IPCC report since the first in 1990 have resulted in a downgrade in the alarmism. The last report for instance predicted "that global mean temperatures would rise by between 1.4 and 5.8 C (2.5-10.4 F) by 2100 compared with their 1990 level." The upper range in this latest report is now put at 4.5 C.
As Julian Pistorius suggests: "Look for more of these sorts of 'downgrades' in the future, until the next environmental scare can be cooked up."
LINKS: UN says man's global warming impact lower than thought - Mongabay.Com
"UN downgrades man's impact on climate" - Julian Pistorius
'Global warming' at a glance - Junk Science
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