...getting...dimmer...

Wow...so I wrote this post yesterday and then, though the stupidity of the mouse click, lost it all in seconds. It ruined my day and my motivation. The internet is testing me. But it will not win. Again, I begin: Unfortunately, log-in issues left me with no computer over the past few weeks. My apologies for the delayed posting. The great news is that the lag gave my friend Andrew Friberg time to learn enough Swedish to watch a show about global dimming in that great language. And it just so happens that this topic makes a great follow-up to my diesel hybrids post. Thanks, Andrew!

In my last post, I hit on the new low-sulfur regs that the Environmental Protection Agency (EPA) is implementing in just a few weeks. Sulfur-reduction efforts aren't just aimed at cars - the (in)famous Clear Skies initiative is also forcing power plants to scrape the sulfur off their hands. Sulfur is one unfortunate by-product of burning fossil fuels, and it's linked to lots of unfortunate problems like asthma, cancer and acid rain. Recently, another evil effect has been making the geeky science-show rounds: global dimming.

First documented in 1969, the global dimming s.o.p. is ensuring that less sunlight reaches the earth as sulfur emissions increase. Scientists in several different regions have measured it. Estimates of the dimming effect between 1950 and 1990 range from 2-3% per decade. Though varied across world regions, researchers found at least some reduction of sunlight in each example. Why is this happening?

It's not quite as simple as it may seem. When burning fossil fuels give off sulfur, it's mainly in an aerosol form, like fog or smoke or Aqua Net. Once they reach the atmosphere, the tiny sulfur particles themselves can act as sunlight reflectors, causing the light that strikes them to propel willy-nilly back into space without reaching the earth. They can also attract lots of tiny water droplets, forming unusually dense clouds that reflect more sunlight than normal clouds. There's also evidence that because the water droplets in these fatty clouds are so tiny, they have a harder time getting together to get their rain on, so the clouds may stick around longer than normal. Conversely, these mutant clouds also have greater heat-trapping qualities at night, when they have no sun with which to frolic.

The "yay" CNN headline is that recent studies have shown the effect decreasing since the early 1990s. The ":(" one is that even as we reduce our sulfur emissions, greenhouse gas levels in the atmosphere continue to rise. Carbon dioxide, water vapor and nitrous oxides, just to name a few, continue to trap increasing amounts of heat. Just for us!

But, it's kind of like a miracle, right? A pollutant that counteracts its own harmful effects? Could we GET any luckier? Hm. Yes. Yes we could. Clearly, it would be irresponsible to ignore the harmful effects of sulfur pollution. They are not small. The EPA estimates that the diesel fuel sulfur regualtions alone will prevent 8,300 premature deaths per year. Promoting the opposite is pretty untenable, as positions go.

Two additional reasons point to preposterousness: sulfur in the atmosphere has a short life, only hanging around for 2 to 3 weeks, while carbon dioxide, for example, is estimated to spend between 50 and 200 years up there. Secondly, since the cooling effects are regional in nature, not all parts of the world are affected evenly. Average global temperature has continued to rise even as global dimming has occurred.

Scientists predict that global dimming and it's reduction will probably lead to changes in regional weather patterns. As use of fossil fuels in the Southern hemisphere increases and sulfur emissions in the Northern decrease, the cooling will shift. But an overall cooling, the yin to global warming's yang, isn't going to happen.

So what IS going to happen? Some scientists, including Atsumu Ohmura of the World Radiation Monitoring Center, believe that as the cooling effect of global dimming decreases, global warming will increase much more dramatically than has been predicted by traditional climate models. Some claims assert warming of up to twice as much as previously thought.

However, the highly-degreed dudes over at Real Climate vigorously, and seemingly without exception, disagree with assessments of global dimming as the new Paris Hilton of climatology and seem to place it more at an American Idol third-runner-up level of importance. It won't destroy everything in its path, but may go on to make a failing solo album and have an affair that ruins a few marriages.

This assertion stems from a horribly technical bit of information known as "error." It's what you see at the end of any political poll - nothing that has uncertainty when measured can be certain. This is even more the case when you're trying to predict the future. Fortunately, wise folks have come up with a way to precisely measure how wrong they probably are. Nice. And the blogging climate scientists referenced above believe that the global dimming effect falls easily within the margin of error of global warming models. In other words, the effect of this one varied and wacky phenomenon is not big enough to make them more wrong than they probably already are.

So don't panic! Don't hang up your reversible anti-pollution cloak and don't stop gathering up the sulfur you've left lying around the living room for 3 weeks. Just count yourself 0.05% more educated about things related to science. And keep working on fighting global warming in your own little way. And go Cyclones!