Someone left me this url - click: Global Dimming - in a comment, I thought it was incredibly interesting and wanted to pass it on. It's curious, I knew that aerosols were damaging and understood the phenomena in a more vague way, but never had I heard this term before. The article basically explains what Global Dimming is and states that its effects had masked Global Warming for years. Kind of a funny at the end of the wiki entry; some scientists suggest reintroducing heavy aerosols into the atmosphere to stave off Global Warming effects... then we're all going to put a bullet in our head to get rid of headaches. I want to post more on this later, after I research it fully. If anyone has any other links to news articles, etc. on this, I would be interested in seeing them.
EDIT - Inel was kind enough to compile a great synopsis on this issue, please read comments for more.
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4 comments:
Hi Christina,
I'll send you some links on this tomorrow.
Thank you, Inel, I appreciate it!
Here's a little background, as I understand it, and why I guess you first heard about global dimming now:
There was a BBC Horizon programme titled simply Global Dimming on British telly back on Thursday, 13 January 2005. The following day, William Connolley wrote about Global Dimming on Stoat and a few days after that gavin wrote about Global Dimming? on RealClimate.
Fifteen months later, on April 18, 2006 an 'improved' version was shown Stateside by PBS as a NOVA documentary titled Dimming the Sun. The day before that broadcast, Beate Liepert (who featured in the programme) wrote about Global Dimming and Climate Models on RealClimate.
You'll get the gist from those posts. TV is fine for entertainment, and in the capable hands of responsible broadcasters like Sir David Attenborough, but in the case of global dimming it is misrepresenting science and scientists in an overly alarming way, imho.
All that background is provided here partly because the linked posts are written in response to the programme, and also because I guess global dimming could be being mentioned again because the NOVA version (Dimming the Sun) is showing again this month (September 2007) in America. Also, the Horizon version (Global Dimming) was uploaded to YouTube in May, and today it was added to TV Links, so opportunities for viewing have blossomed recently!
Since Peter Cox of the UK's Met Office Hadley Centre was also given airtime in the programme, I thought I'd also send you this link from Met Office FAQs:
What is global dimming and what relevance does it have to climate change?
'Global dimming' is the term used to describe the observations from surface instruments showing a general reduction in the amount of solar radiation reaching the ground since about 1960, globally amounting to 2–3% per decade, up to about 1990. The dimming is variable from place to place, with some sites even showing a brightening over the period, but greatest in northern mid-latitudes. However, more recent research indicates that this trend reversed in about 1990 and since then there has been some 'global brightening', although being indirectly measured from satellites these more recent estimates may be less robust. It seems likely that the reductions, and perhaps the recent increases, may be due to changes in aerosols such as sulphates and soot (black carbon). The most recent version of the Hadley Centre climate model (HadGEM1), which includes both sulphate aerosols and soot, does simulate a reduction in surface solar radiation, though not as great as that actually observed. Neither the observations nor the implications for predictions of climate change are yet clear, and this is a subject of active research.
Unfortunately, the "documentary" purports to be designed to get people to act to combat global warming and global dimming, but it does that by giving false impressions of what scientists know, and to what degree of certainty, about different components of radiative forcings and how those components interact. The programme made some extreme claims, by drawing conclusions based on certainty about areas that are (still) far from certain.
Wow, Inel, you did a fantastic job condensing all of that info for me! The compiled links and your synopsis made for a very interesting read, thank you so much. I agree with you, the transcript from the program (and all the links, really) provided insight as to the global dimming phenomena, but also on lessons to be learned on treading carefully between educating and engaging people, and overzealousness that in the long run overshadows the intended outcome. Thank you again, you just did all my research for me ;p
Christina
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