The Global Dimming Hypothesis

I saw a PBS Frontline program on this topic awhile ago, and it got my febrile little brain going.

For those who didn't see the program or are unfamiliar with the hypothesis, a brief summary: global dimming is their name for the reduction in global solar heating caused by haze and increased clouding, which in term were driven by human effects--pollutants. This effect has been reduced--at least in many areas of the world--by reforms reducing pollutants by introducing technologies that scrub exhausts from industrial plants and vehicles. The resulting clearing of the air has allowed the full weight of the distinct process of global warming--the heat-trapping effect of invisible "greenhouse" gases--to be felt only recently. The global dimming hypothesis suggests that the full potential effect of global warming in the next century may need to be bumped way upward.

A very depressing prospect, if true, since no doubt much damage has already been done and much more will occur before we can change significantly the pattern of release of these organic gases from burning fossil fuels. I'm not sure that "going agro" with bio-fuels would even change that pattern all that much (subject for research).

But that's not my point of this post. My first thought was, well, China isn't going to have that temperature problem (though they would experience the devastation of rising sea levels), because their pollution is bad and getting worse. Global dimming isn't over, over there.

This led to a more general thought: We don't want to go back to the bad days of smog and pollution, but the amount of heat directly absorbed on earth, no doubt a massive quantity, may be something which we could influence in a favorable way. We could choose to block sunlight, through judicious geographic selection (over deserts? or icecaps?) or partially, through filters suspended in the sky (pie-shaped?). We could put massive banks of solar collectors just above ground, and collect the energy (let's just make the panels easily replaceable as the science of photovoltaic materials progresses).

I'm really encouraged by these thoughts, contrary to the original thrust of the documentary report. For one thing, this report is coming from a post-G.W. point of view (global warming, not the Bushite): it does take the time to go over that science, but the focus is on the new science indicating that the recent dynamics in the geophysical realm are the result of changes, each following different paths over time, of two opposing results of human-generated mess--global warming, and its dampener, global dimming.