Climate Change 101

I might have been able to gloss over Reuters' latest ignorance-fest on global climate change if it hadn't been for the following paragraph:

Scientists differ as to whether global warming is caused by man-made emissions of carbon dioxide and other "greenhouse" gases, by natural climate cycles or if it exists at all.

This is the stock disclaimer that you'll see in just about any article about climate change. I assume it's mandated by Rupert Murdoch and his corporate peers. It is also only the beginning of the inaccuracies that characterize this article.

The Reuters article suggests that cutting down on fossil fuel use will actually increase the warming effect of greenhouse gases because it will reduce emissions of particulate matter that reflects a portion of the sun's energy, thereby creating a cooling effect. The only reference that the author provides is Peter Cox of the Hadley Centre for Climate Prediction and Research.

Because the science in the article is so right, yet the conclusions therein so wrong, I'm going to give Dr. Cox the benefit of the doubt and assume that the author is mischaracterizing Cox's research.

Before going any further I feel as though I should review the [very] basics of what we know about anthropogenic climate change.

Greenhouse gases (GHGs) are the compounds responsible for 'global warming,' which act by absorbing infrared radiation and turning it into heat in the atmosphere. The most significant two in terms of human impact are carbon dioxide (CO₂) and methane (CH₄). Carbon dioxide gets more attention because we've introduced a lot more of it into that atmosphere, but methane may have as significant of an effect because its capacity for converting solar radiation into heat far surpasses that of carbon dioxide. Finally, while methane stays in the atmosphere for about ten years, carbon dioxide can remain for as long as a century. MSN Encarta has a page full of good info on GHGs.

Particulate Matter (PM) is simply free particles in the air which can range in size from dust and smoke (large) to automobile and industrial exhaust (small). In addition to the fact that this stuff isn't great to breath, en masse it causes infrared solar radiation to be reflected away from earth, creating a cooling effect referred to as 'global dimming.'

The possibility that the cooling effect of atmospheric particulate matter might be acting as a buffer against warming from GHGs has been gaining acceptance for the last several years (though the Reuters article seems to indicate that this relationship is a recent discovery of Dr. Cox).

It's even possible that we only noticed the global warming effect of GHGs because of efforts in the 1970's to cut down on particulate pollution.

[Atsumu Ohmura, director of the World Radiation Monitoring Center] believes that during the '60s and '70s, global dimming, caused by particulate pollution, buffered the climate against global warming, caused by greenhouse gases. As the increasing amounts of gases warmed the Earth, the increasing amounts of particulate pollution reduced the sunlight that reached its surface, thereby cooling the planet. In other words, one form of pollution counteracted the other.

The Reuters article cautions against reducing petroleum consumption lest we reduce particulate pollution and exacerbate warming, but by all appearances we have already done exactly that. We're faced now with only one feasible option: do what we can to greenhouse gas emissions before it's too late. This effort ought to focus especially on methane, since it only remains in the atmosphere for about a decade, and thus will produce the more immediate results that we need if we're going to be around for the hundred years it will take for atmospheric carbon dioxide levels to drop significantly.

Finally, as far as oil goes, the Reuters article failed to note that the combustion of petroleum produces both particulate matter and carbon dioxide. Even if the cooling effect of PM were stronger than the warming effect of CO₂, the CO₂ will remain in the atmosphere for far longer, causing additional warming in the future.

I find it unlikely that we will be capable of reducing our emissions of either greenhouse gases or particulate matter to negligible levels in the foreseeable future. Be that as it may, by releasing these compounds into the atmosphere we are conducting an ecological experiment that has never been attempted before, with our health and possibly our survival at stake on the outcome. We sway the odds in our favor by keeping the experiment as close to the 'control' as possible, and that means reducing our emissions as much as we are able.

Double post (and I'm more likely to remember to respond to comments if they are posted on my site.)