I can see dimly now: air pollution is on the rise in most areas of the world.punchstockPosted on 03/12/2009 6:43:21 PM PDT by neverdem
Darker skies have uncertain effect on global warming.
Air pollution that is harmful to human health has increased over all populated continents except Europe since 1973, according to an extensive survey.
I can see dimly now: air pollution is on the rise in most areas of the world.punchstockThe results play into a long-standing debate over whether the Earth's skies are dimming or brightening, how this affects the amount of sunlight reaching the planet's surface and what that means for climate change.
Two studies published in Science in 2005 concluded that a global dimming trend that began in the 1950s has been replaced since 1990 by global brightening1,2. The likely effect of all that extra solar radiation reaching the Earth's surface would be faster global warming.
Now a study published in Science concludes that in fact skies became dimmer over most land areas between 1973 and 20073. Only in Europe have skies become cleaner than they were some 30 years ago; there, industrial production declined sharply after the collapse of communist governments around 1990, and air quality regulations have had a big effect since. Air quality in North America has changed little during the study period.
Kaicun Wang, an atmospheric scientist at the University of Maryland in College Park, and his colleagues based their conclusions on visibility measurements, a good proxy for aerosol pollution, from 3,250 meteorological stations around the world. They found that visibility has tended to decrease over that period, the most pronounced dimming having occurred in South Asia and South America. Various types of aerosol have contributed to the trend, but sulphate and soot particles from fossil fuel burning are the main culprits, the team found.
"Most countries have realized by now that air pollution is a serious health risk," says Wang. "But attempts, such as China's, to regulate air quality have not yet borne fruit."
Significant questions remain about what these results means for climate change, because soot and different kinds of aerosols can affect cloud formation in very different ways.
In come circumstances, aerosol particles can act as seeds for clouds, which help to reflect the Sun's rays back into space and so cool the planet. Aerosols can also reduce cloudiness, however, as probably happens in northern China, meaning that the net effect of aerosol pollution on global temperatures is worryingly uncertain.
Another complication is that soot from burning biofuels, widely used for cooking and heating in India and Africa, tends to absorb sunlight rather than scattering it back into space. This means that it warms the troposphere in much the same way as carbon dioxide and other greenhouse gases4.
Wang suspects that the poor understanding of these effects might explain why previous studies, which measured incoming solar radiation rather than visibility, concluded that the skies have brightened over most land areas, including China.
"The issue of global dimming versus global brightening is not just a question of aerosols," agrees Martin Wild, an atmospheric scientist at the Swiss Federal Institute of Technology in Zurich, who led one of the Science studies in 2005. "One must indeed consider clouds as well."
Wang is optimistic, however, that the air in China could become cleaner in the near future — as it did in Europe in the 1980s and previously in North America — if coal is replaced by oil and natural gas as an energy source, and if particulate filters in cars and factories become more common.
So they left something out of the ‘computer models’?
I am a computer engineer, and whenever I hear someont say they rely on computer models I laugh. I can make a computer model tell you anything you want it to tell you.
There are some that are worthwile because they are MADE to be worthwile (like tomorrow’s weather) but long term they are worthless.
When I was a kid, we called “climate change,” the weather. “Dimming global skies” was called night.
It really doesn’t matter what effect air pollution clouds have on climate — send algore money and he will fix it. And gubmint will contact you, so you will know what you need to give up to eliminate future threats of this kind.
Bull Soup. Darker skies lower temperatures, period. The correlation between major volcanic eruptions and major cold snaps is clear, unambiguous, and far more established than any link between CO2 and global warming.
Sounds like the cheapest way to stop the idiots who worry about AGW from losing sleep is to generate more pollution!
It's not that simple. Dark skies at night result in higher temperatures -- this is well-known. Dark skies in daytime do cause cooling, of course.
Something? They have left a lot out of their models. As a computer engineer you would probably like to know they have also not included ocean temps, cloud cover or atmospheric CO2 concentration. In fact they have just recently admitted that they don’t know where some of the supposed CO2 in the atmosphere has gone and are going to launch a satellite later this year to try and find it. Garbage in garbage out.
I'm calling BS on this statement.
“...based their conclusions on visibility measurements, a good proxy for aerosol pollution, from 3,250 meteorological stations around the world. ...”
Are these the same meteorological stations that gave such excellent results about the temperature?
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