Improved air quality contributing to global warming?
Perhaps the law of unintended consequences has struck again. Or perhaps we really don't have a clue about what might be causing the earth's atmospheric temperature to rise. Either way an interesting new theory has popped in the study about what may be causing global warming. It seems that all the progress made to clean up skies over the last few years may be a contributing factor to more solar radiation reaching the ground. Skies over North American and European cities have gotten dramatically clearer since the 1960s. Aerosolized atmospheric particles have dropped by more than sixty percent in the last three decades in Europe while the amount of solar radiation has gone up. It now appears that the pollutants may have been directly reflecting radiation. Previously it had been thought that clouds seeded by the particles were reflecting the suns rays but current data is showing little impact on solar radiation on cloudy days. The new studies imply that the effect of reduced atmospheric pollution may actually account for half of the global warming effect. It looks like the more we learn the less we really know.
[Source: New Scientist]
Reader Comments (Page 1 of 1)
meme 11:38AM (7/11/2008)
Add another "check" to the list of "Times Someone Has Conflated Regional Warming With Global Warming". Read the article more carefully. They're talking about *as much as* half of *Europe*'s warming.
Secondly, it's *long been known* that reducing SO2 pollution, which the paper in question mainly focuses on, raises temperatures. It says this *right in the introduction of the paper*. For example, volcanic SO2 emissions are the largest player in causing "volcanic winter". What this paper is pointing out is that much of the reduction comes from increasing the clarity of the atmosphere, not from reducing cloud seeding, at least over Europe.
Third, the whole landmass of Europe has historically been like California is today, but they've been doing major efforts to clean up their act. It's hardly representative of the world as a whole. In fact, whatever cleanup Europe's done, globally, I'd expect it to have been more than offset by the new smog pouring out of China.
Fourth, while cloud-seeded cooling involves *reflectance* of solar radiation, direct aerosol-induced cooling involves *absorption* of the radiation at higher altitudes. The heat's still there -- just not at the surface over the places emitting the smog.
Fifth, the paper doesn't talk at all about this invalidating climate models. It talks about this changing the *mechanism* of SO2 cooling, but the only time it mentions the word "model" in the entire paper is in reference to models of how much of aerosol cooling comes from cloud seeding as opposed to direct aerosols.
Lastly, the article in question itself states:
"With respect to the temperature evolution in central Europe, increasing aerosols were apparently effective in masking greenhouse warming after the 1950s [Wild et al., 2007], whereas the observed direct solar forcing due to the strong aerosol decline since the mid-1980s has reinforced greenhouse warming, although the reduction of absorbing aerosols (such as black carbon) might have dampened the reinforcement."
Translation: there should have been *more* warming over Europe in the 1950s-1970s, but the increase in smog masked this. Now we're seing the effects of what it was hiding.
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tankd0g 1:01PM (7/11/2008)
Airplanes with bigger contrails, that'll solve global warming. :)
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JAMF 2:31PM (7/11/2008)
In Januari 2005, there was a "Horizon" documentary about "Global Dimming" on the BBC. It took quite a while for that message, comming from audio-visual , to reach paper.
http://video.google.com/videoplay?docid=-2058273530743771382&q=global+dimming&ei=66V3SIOeFo3yiQKZ3LWOBw
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Geoff 3:55PM (7/11/2008)
There was a Nova special about Global Dimming a couple of years ago. Basically air pollution and airplane contrails block some of the sun, and with cleaner air, the earth will warm faster.
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Chris 7:41PM (7/11/2008)
"It looks like the more we learn the less we really know."
That's all we 'deniers' were ever saying. The "Theory of Global Warming" has not yet become a law of geophysics.
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Jay 2:39AM (7/12/2008)
The message I took away from the Global Dimming PBS show was that global dimming was masking, or counteracting, global warming, making the effects of our greenhouse gas emissions seem less severe than they would have been without all the simultaneous particulate emissions. The speculation is: clean up the particulates/contrails, and the real effects of greenhouse gasses might escalate dramatically. We definitely should keep studying these phenomena, and let the scientific process do its thing, but let's not throw up our hands and say: "See, nobody knows what's going on, so lets keep our heads in the sand for a few more years." Let's reduce our greenhouse gas emissions and stimulate the economy by putting military contractors to work rebuilding American infrastructure.
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swaan 4:34PM (7/13/2008)
I for example am currently favouring the idea that the whole solar system is warming. NASA has never confirmed it but there is quite a bit of evidence suggesting that It might be true. It really shows that even if we do a lot of research - things might change around us and the scientists a baffled once again.
In this case it might be that the clockwork of our solar system is changing and causing huge changes everywhere. We have a very sharp rise in natural disasters over the last 40 years. Other planets like Mars and Venus have huge atmospheric changes happening. Sun doesn't have a singe sunspot right now, but it should have!
NASA is good at hiding stuff. There are thousand of rumors about various incidents. I believe most of you guys also know that US agencies have a lot to hide from the general public.
After all who wants to distrupt our daily lives and hurt the economy?
You can't tolerate chaos in a system. So you hide it.
This is what I think of the climate change. I might be wrong but remember - truth will never run into your arms, you have to go look for it.
Cheers,
Swaan
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jay 1:18AM (7/13/2008)
i thought the debate was over
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Scott 3:56PM (7/14/2008)
Just curious... what city is that in the photo?
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