Forget CO2: Aerosols are the Global Warming Culprit

Tech Tips, Repairs, & Maintenance

July 18, 2009

By Bob Difley

As if we didn’t have enough to be concerned about with CO2 emissions and global warming, climate scientist Drew Shindell of the NASA Goddard Institute for Space Studies says we need to be concerned also about aerosols.

Though greenhouse gasses, notable CO2, are at the center of the political debate on what to do about control global warming, most climate scientists agree that since CO2, the primary greenhouse gas, stays in the atmosphere for hundreds of years, what we do now, today, to control CO2 and the other greenhouse gasses, will have little effect for decades. And as the emerging global economies of China, India, and Brazil continue to pump greenhouse gasses into the atmosphere, it is unlikely that the world’s total greenhouse gasses will decrease much in the near future.

What Shindell and other researchers are finding, is that much of the atmospheric warming observed in the Arctic since 1976 may be due to changes in tiny airborne particles called aerosols. Aerosols are emittted by natural sources, such as volcanoes, dust storms, sea spray, and vegetation emissions, as well as manmade sources like agricultural burning, industrial pollution, and fossil fuel conbustion. These aerosols can directly influence climate by reflecting or absorbing the sun’s radiation. The small particles also affect climate indirectly by seeding clouds and changing cloud properties, such as reflectivity.

Shindell’s model suggests that aerosols likely account for 45 percent or more of the warming that has occurred in the Arctic during the last three decades. The fact that similar warming has not occurred in the Antarctic indicates that manmade sources likely account for the cause since the Arctic is closer to dense human population centers than the Antarctic.

To complicate the problem, research shows that two types of aerosols, sulfates and black carbon–both products of human activity–play a critical role. Sulfates come from the burning of coal and oil and scatter incoming solar radiation and have a net cooling effect on the climate. And with the passing of a series of laws over the last three decades designed to improve air quality and public health, sulfate emissions have been cut by 50%, which in turn have reduced their cooling effect causing global temperatures to rise.At the same time, emissions mainly from Asia’s industrial processes and the burning of diesel and biofuels, have emitted black carbon aerosols that absorb incoming solar radiation and cause a strong warming effect.

The NASA researchers also compared the climatic impacts of the transportation sector to the power generation sector and found that the most efficient way to tackle climate change–from both CO2 and aerosols–is to regulate the transportation sector.

Though coal power plants produce lots of CO2, they also produce lots of sulfates that mask the warming effect of the CO2. However, motorized vehicles release both CO2 and black carbon (both warming agents), but no sulfates. As a result, transportation has a big warming impact on climate that’s more important than just tallying up its carbon emissions.

Maybe this new study suggests that in the current political environment regulators and politicians should focus on the transportation sector before the power generation sector. I suppose that’s good news, since there is something we RVers can do to cut down on vehicle emissions, like buying more fuel efficient vehicles, driving less, and continuing the transition toward electric and hybrid vehicles, but little we can do for now about the power generators. Or we could buy a Tesla for a toad, which is a pure-battery electric vehicle with a range of 240 miles per charge, a 130 mph top speed, and goes from 0-60 mph in 3.9 seconds. My idea of going green.