Cleaner Air Could Speed Global Warming 344
Hugh Pickens writes "Scientists estimate that the US Clean Air Act has cut a major air pollutant, sulfate aerosols, by 30% to 50% since the 1980s, helping greatly reduce cases of asthma and other respiratory problems. But NPR reports that this good news may have a surprising downside: cleaner air might actually intensify global warming. One benefit of sulfates is that they've been helpfully blocking sunlight from striking the Earth for many decades, by brightening clouds and expanding their coverage. Researchers believe greenhouse gases such as CO2 have committed the Earth to an eventual warming of roughly 4 degrees Fahrenheit, a quarter of which the planet has already experienced. But thanks to cooling by aerosols starting in the 1940s, the planet has felt only a portion of that warming. And unlike CO2, which persists in the atmosphere for centuries, aerosols last in the air for a week at most, so cutting them would probably rapidly accelerate global warming. The author of 'Hack the Planet' says: 'As we take away that unexpectedly helpful cooling mask, we're going to be facing more global warming than we expected.'"
Re:Trolls. Everywhere. (Score:4, Interesting)
I don't think anyone is arguing we repeal the clean air act or anything like that. We all like breathing. Also it really wouldn't help. It'd be like if your house caught fire and to avoid death you go to another room. Sure it helps you ignore the problem a few minutes at best, but you aren't doing fuck all to put out the fire. (apologies for the shitty analogy, where is BadAnalogyGuy when you need him?)
Re:A little known fact (Score:5, Interesting)
Yeah, it's odd that an ~18 page summary for nonscientists doesn't include all the nuances in a ~1000 page report filled with scientific jargon.
The summary's forcing chart [www.ipcc.ch] clearly shows a huge, lopsided error bar on the cloud albedo effect, and lists the Level Of Scientific Understanding as "low". This is a copy of figure 2.20 on page 203 of chapter 2. In both charts, notice that the CO2 forcing is very large and known far more precisely.
The particular statement you found, that "the warming seen over the last few decades is entirely attributable to the reduction in aerosols in recent years" isn't something I've seen in chapter 2. The bottom panel of figure 2.22 on page 206 seems like the closest match to your statement, but it's a projection based on emissions over 20 years in the future. Could you specify the page number where you found your statement?
I'll note that your claim isn't necessarily contradicted by figure 2.20 because that's the radiative forcing integrated from 1750-2005, whereas you're referring to something like 1985-2005... right?
What about photosynthesis? (Score:3, Interesting)
The author of 'Hack the Planet' says: 'As we take away that unexpectedly helpful cooling mask, we're going to be facing more global warming than we expected.'
...along with more CO2-scrubbing photosynthesis caused by more sunlight reaching the the ground. Did he not consider this?
Re:When Trolls Fly (Score:3, Interesting)
>>They want to pump sulfur compounds into the atmosphere, including. When I heard this, also on NPR, I wanted to scream, "What about acid rain you stupid fuckers!?"
They've thought about it. I've read the analysis and it's reasonable. The reason WHY they want to use SO2/SO4 is because we know that this is what happens when volcanoes erupt, and it doesn't cause catastrophic effects. There's plenty of other possible solutions - really, anything that increases the albedo and cloud nucleation would work. I think they've also suggested salt sprayers, for example.
Given how cheap it would be to build one of these things (Bill Gates could fund it out of his evil scientist slush fund), I find it hilarious and sad at the same time that people will talk about how great the threat of AGW is on one hand, and absolutely, positively, refuse to consider any alternative besides us moving into caves and eating granola all day. (And 6 billion people dying in the process, but it's considered gauche to talk about that.)
Comment removed (Score:4, Interesting)
Re:Trolls. Everywhere. (Score:4, Interesting)
Climate scientists have known about the negative forcing of areosols since at least the 1950's. It's the half truth behind the widely repeated troll that "most climate scientists predicted an ice age in the 70's". I know of no reputable climate scientist* who would advocate repealing the clean air act and going back to pea-soupers [wikipedia.org] and acid rain as a sane method of tackling AGW.
* = Eli Kintisch (the author of the original opinion piece in the LA times), does not advocate increasing pollution. He is simply pointing out that man made areosols are currently masking the full impact of CO2 emissions. His book Hack the Planet [nature.com] is an informative work about the pros and cons of geoengineering options that governments may be tempted to consider if things continue on a BAU basis. As the Nature review points out; "Kintisch is skeptical about the idea that we can tame and control ecosystems, let alone the whole planet."
Like the vast majority of scientists his prefered geoengineering option is to wind down the current uncontrolled geoengineering experiment in a responsible manner, but as we have seen there is some mighty stiff oposition against that option from powerfull vested interests. And how surprising is it to learn that they are the same vested interests who, for almost a century, successfully used anti-science and economic alarmisim to fight tooth and nail against any and all proposals for clean air regulations?