From Nature
Asian pollution delays inevitable warming
Dirty power plants exert temporary protective effect.
The grey, sulphur-laden skies overlying parts of Asia have a bright side — they reflect sunlight back into space, moderating temperatures on the ground. Scientists are now exploring how and where pollution from power plants could offset, for a time, the greenhouse warming of the carbon dioxide they emit.
A new modelling study doubles as a thought experiment in how pollution controls and global warming could interact in China and India, which are projected to account for 80% of new coal-fired power in the coming years. If new power plants were to operate without controlling pollution such as sulphur dioxide (SO2) and nitrogen oxides (NOX), the study finds, the resulting haze would reflect enough sunlight to overpower the warming effect of CO2 and exert local cooling.
But this effect would not be felt uniformly across the globe and would last only a few decades. In the long run, CO2 would always prevail, and the world could experience a rapid warming effect if the skies were cleaned up decades down the road.
“The paper highlights the fundamental inequity and iniquity of anthropogenic climate change: ‘enjoy now and make others pay later’,” says Meinrat Andreae, an aerosol expert at the Max Planck Institute for Chemistry in Mainz, Germany, who was not involved in the work. In fact, he says, dirty coal plants could be seen as “a very primitive form of geoengineering”.
The study, which is under review at Atmospheric Chemistry and Physics, builds on a well-established idea. Global temperatures were relatively stable in the decades leading up to the 1970s, even as fossil-fuel consumption shot up. Then industrialized countries began curbing SO2 and NOX to reduce acid rain and protect public health — and temperatures increased rapidly. The latest work, led by Drew Shindell at NASA’s Goddard Institute for Space Studies in New York, looks at how the climate effects of air pollutants and greenhouse gases could play out over time and geography.
read the remainder at Nature
h/t to Leif Svalgaard
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Re Ferdinand Engelbeen (08:26:00)
Ferdinand, thank you for your explanation and links. But surely all these smart IPCC scientists and modellers must have taken these obvious things into consideration. Do you know of any paper that considers the lack of local cooling over the emitting areas but stills maintains the important effect of sulphates? Is perhaps the so-called aerosol indirect effect more important and less regional? Is all of this discussed anywhere in the mainstream literature?
Mikel
Yes, one of the climategate emails speculates whether sulphate emissions from India and China might be the reason why there hadn’t been the predicted warming – but that it was hard to tell because they didn’t have reliable emissions data.
Except … if they don’t have reliable emissions data, then how can they have any confidence in what’s been coming out of their climate models? Or indeed, if they don’t have emissions data for today, they probably don’t have any for the 1950s or 1960s either which was when they ASSUMED it was responsible for the world cooling whilst CO2 was rising.
Now what was that about “the science is settled”?
“A simple question that I want Climatology to answer: What was the climate supposed to be if AGW hadn’t intervened” – Jryan
Well, I suppose one could plot a trend line from, oh, about 1700 (end of the little ice age) to 1940 (start of mass global CO2 emissions) and extrapolate…
…except I suspect that’d probably show more warming than we’ve actually had!
No no no, Jo Nova had it right ages ago when she PROVED global temperatures are driven by US Postal charges.
(I got to think of something to get my hands on this limitless research grant money. Looking for et al’s, any takers)?
“If new power plants were to operate without controlling pollution such as sulphur dioxide (SO2) and nitrogen oxides (NOX), the study finds, the resulting haze would reflect enough sunlight to overpower the warming effect of CO2 and exert local cooling.”
The heat waves in UK and France in 200? & ? were blamed on the fact that we had controlled pollution so well that there was no longer this haze protecting us from the warming effect of CO2. That argument has fallen by the wayside since then because we have had such rubbish summers since.
Does that not indicate that the warming effect of CO2 is suspect?
I would have thought it would be better to concentrate on the health hazards of living in that noxious cloud.
Ah, we seem to be full throttle into a degenerative research agenda now, as the Team desperately tries to explain why model predictions are failing to match reality.
Wouldn’t the effort be better spent trying to understand the fundamental mechanisms, rather than the smaller effects? It is entertaining, though, to observe the tortured logic. (And we thought pollution was a BAD thing! Silly us.)
Hey, sceptics, repeat after me:
Polluters, united,
will never be defeated !!♪♪♪
Mikel Mariñelarena (04:54:55) :
“I´ve asked this to several scientists but never got any conclusive reply. If the negative forcing of anthopogenic aerosols is comparable to that of CO2 alone (AR4), why are we not observing their cooling effect over the emitting areas or downwind from them?”
UHI :o)
“Baa Humbug (09:58:23) :
No no no, Jo Nova had it right ages ago when she PROVED global temperatures are driven by US Postal charges.”
We’re doomed…
http://joannenova.com.au/2009/05/shock-global-temperatures-driven-by-us-postal-charges/
Again, another “conclusion” based on computer models, not on observation. And how do these models work? Right, sulphate aerosols are programmed to give a negative feedback that exactly accounts for the 1945 – 1976 cooling. Unfortunately, there were no empirical studies in those days that actually measured the amount of sunlight that was supposed to be reflected back into space by these aerosols. It was enough to assume values that were convenient to their man made global warming story.
Once upon a time, they used to show movies in a continuous loop, with viewers coming in on a continual basis. Every so often, someone would utter, “oh, this is where we came in.” I feel like uttering the same words now, as we go round again with the same old tautological nonsense.
Mikel Mariñelarena (09:54:28) :
Do you know of any paper that considers the lack of local cooling over the emitting areas but stills maintains the important effect of sulphates?
The IPCC takes the effect of sulphate aerosols quite high. If they shouldn’t, then the effect of CO2 is much less than expected in the models: there is an offset between aerosol influence and CO2 influence (forcing + feedbacks). This was discussed years ago on RC:
http://www.realclimate.org/index.php/archives/2005/07/climate-sensitivity-and-aerosol-forcings/ (see my comment at #14)
and further at
http://www.realclimate.org/index.php/archives/2006/02/an-aerosol-tour-de-forcing/ (my comment at #6 and further on)
The link to the Heald paper (most aerosols in the free atmosphere are of natural origin – from vegetation) doesn’t work anymore. Here is the new link:
http://acmg.seas.harvard.edu/publications/heald_2005.pdf
There are several other publications that show that natural aerosols are underestimated (and anthro aerosols overestimated):
http://www.sciencemag.org/cgi/content/abstract/312/5771/261
http://www.sciencemag.org/cgi/content/abstract/314/5804/1419
and many more…
Different models give different answers for regional effects, including aerosols. But as CO2 is quite evenly distributed, the largest regional effect is from aerosols, thus should be seen downwind from the main sources. The IPCC (TAR) has some pictures about the different influences:
http://www.grida.no/publications/other/ipcc_tar/?src=/climate/ipcc_tar/wg1/fig6-7.htm
But be aware of the difference in scales! And in graph h) they include sea salt with human sulphate aerosols for the first secundary effect…
Is perhaps the so-called aerosol indirect effect more important and less regional? Is all of this discussed anywhere in the mainstream literature
See the IPCC figures for the spread of the different effects…
The first indirect effect is that more clouds are formed due to more fine sulphate aerosols in the atmosphere which act as kernels for water drops, that extends somewhat further than the aerosol effect itself (in theory). The second indirect effect is that more fine drops gives longer lasting and brighter clouds, thus more reflection to space. The second indirect effect is difficult to measure/prove, but the first indirect effect should give a huge difference in cloud trends, but as far as I know, no such trends are measured, where “global dimming” (and reverse!) probably is more related to water vapor than to aerosols.
Brown/black aerosols have the opposite first indirect effect, as these absorb more solar energy, thus heating up the lower atmosphere, which reduces cloud formation. This should be seen over the Indian Ocean between the highly polluted NH and the much cleaner SH near the equator (the ITCZ forms a strong barrier against aerosol exchanges). But there is hardly a difference in trends:
http://meteora.ucsd.edu/~jnorris/reprints/io_cloud.pdf
LOL
But this is exactly what happened during prior to and during the early industrial revolution and why may urban thermometers over 100 years ago did not record the real amount of sunlight that would have reached ground level had the air been cleaner. The hockey stick graph would really be shaped differently if there was a Clean Air Act 200 years ago.
So WattsUp cuts and pastes an article from nature with a headling disputing SO2s impact on the climate.
Sulphergate……
Vincent (11:22:15) :
Unfortunately, there were no empirical studies in those days that actually measured the amount of sunlight that was supposed to be reflected back into space by these aerosols.
There were no satellites around in that period, but we have some places where the incoming sunlight was measured from the mid 1950’s:
From Wild e.a. http://www.sciencemag.org/cgi/content/abstract/308/5723/847
The free supporting material is interesting:
http://www.sciencemag.org/cgi/data/308/5723/847/DC1/1
Where you can see that in several countries the “global dimming” reverses around 1975, but as China is also positive after 1985, that seems not connected to aerosols but to clouds and/or water vapour…
Several commenters have asked for references in the literature for the sulfate cooling effect — here are a couple:
Bellouin, et al. Global estimate of aerosol direct radiative forcing from satellite measurements. Nature. Dec. 29, 2005. 1138-1141
Streets et al. Two-decadal aerosol trends as a likely explanation of the global
dimming/brightening transition. GEOPHYSICAL RESEARCH LETTERS. 2006. 33, L15806
Danger of epicycles here:
Start with a premise: Sun and stars go round the world or CO2 is the cause or the main cause of any warming.
Lock that into the model and never question it. So how to explain anomalies?
Epicycles in the one case but in this case perhaps aerosoles.
But if aerosoles later prove problematic? Never mind, use that as a starting point for further adjustments. Look for something that affects the affect of aerosoles.
Keep tweaking to perfect the models. Great need for lots more grant money here of course.
Of course if your starting ‘locked in and proven’ premise is wrong then you are wasting your time and our money.
First it was “Global Cooling”, then it was “Global Warming”.
“Global Warming” evolved into “Climate Change”, which now
is “Delayed Climate Change”.
It sounds like…….something has some effect somewhere…in a 100 years from now….
Fills me with a feeling of sceptisism.
Is ‘doubles as a thought experiment’ the new ’empirically unverified’?
I stopped reading when I got to the part; “A new modelling study….”.
In other words little boys playing with big computers and predicting the future. No thanks.
Oh Boy! So we have a trivial solution: Take all the SO2 / NOx scrubbers off and take the cat converter off my car! Great!
Oh, and while we’re at it, lets put a double dose of sulphur in the “at altitude cruse” tanks of jet liners. Typically large jets have several, with one used for take off / landing and another for altitude cruse. So we can dump LOADS of sulphur at altitudes of 35,000 to 45,000 feet all over the place. No Problem!
Glad we could find such an easy solution to this problem. (Or such an easy solution to the ‘non problem’ …)
/sarcoff>
“Image from SEAWIFS: An often opaque layer of polluted air covers much of eastern China in this image”
Man I could have sworn I’d seen that in the movie Silent Running with Bruce Dern. 1972, anybody remember that?
“China and India, which are projected to account for 80% of new coal-fired power in the coming years”
Please be more specific, like China 70% and India 10% for example.
John (15:31:21) :
Bellouin, et al. Global estimate of aerosol direct radiative forcing from satellite measurements. Nature. Dec. 29, 2005. 1138-1141
Streets et al. Two-decadal aerosol trends as a likely explanation of the global
dimming/brightening transition. GEOPHYSICAL RESEARCH LETTERS. 2006. 33, L15806
John, the Bellouin paper was discussed on RC some years ago, with my comment at #6 and following comments:
http://www.realclimate.org/index.php/archives/2006/02/an-aerosol-tour-de-forcing/ The discussion was the shortest ever on RC, I suppose…
The Streets paper supposes that global dimming and (sulphate) aerosols are linked, but that is contradicted by the figures from China, where incoming sunlight increased since 1985, while sulphate emissions soared… As global dimming was a worldwide item, even at places far away from pollution, this points more to cloud cover and water vapor than to aerosols. See the trends at different places on earth:
http://www.sciencemag.org/cgi/data/308/5723/847/DC1/1
A lot of you need to remember that sarcasm causes Global Warming.
Ferdinand, John, thanks a lot for the links.
As James Hansen admitted on his “Venus runaway” paper last year, aerosols are the Key Issue in the AGW debate. Also, there is no other way to explain the contradiction between models and observations pointed out by Lindzen than to plug in a high negative aerosol forcing. http://www.timbro.se/pdf/060505_r_lindzen.pdf