On the other hand, I’m also taking the opposite-of-opportunity to be publicly on record disagreeing with Ray Pierrehumbert.
Ray cogently argues at RC that the long lifetime of CO2 makes it more rather than less urgent to deal with CO2 rather than with shorter-lived perturbations. To the long-now view, to the science fiction reader, to the person who wants to see our planet prosper for another billion years and not just another century, this is cogent. But it’s really a question of perspective.
I think we have to do what we can to avoid a crash; that is, a sudden decline in world population. Crashes (which have occurred on national scales) are very nasty times, and there are arguments that they tend to follow hard on the heels of periods of great prosperity. (See Jared Diamond’s book Collapse.) This makes short-term perturbations of special importance. As I argued at RC
Two decades is the amount of time we need to buy to break even, as a rational carbon policy should have set in two decades ago. The way I see it is that the time we “buy” just compensates for our past foolishness, not for our future foolishness.
If I may be allowed a moment of armchair economics…
The foot-draggers say we should delay policy change for as long as possible because we will be wealthier in the future and better able to afford to act. The problem is twofold: 1) as long “as possible” may already have expired and 2) even in the absence of climate impacts, conditions have changed enough that future growth in per capita wealth along the model of the last 200 years is in no way guaranteed.
The reason to delay impacts for as long as possible (even at the expense of the long term outcome) is the flip side of this argument. At some point climate change may well become so severe that per capita wealth will begin a long term, accelerating downturn. At that point, no mitigation at all will be affordable. This argues for mitigation as early as possible because we can’t afford it once it’s too late; but it also argues for mitigation whose effects are as early as possible.
Hot on the heels of this exchange, I received another press release from Alexandra Viets making the case. (Other people should send me press releases, too. I have no compunction about just posting them!) And here it is:
Cancun, Mexico, December 7, 2010 – Concern for high-mountain regions of the world is rising, according to a new report released by the United Nations Environment Programme (UNEP) today, which states that the Himalayas and many other glaciers are melting quickly, threatening lives by flooding, and by reducing the region’s freshwater supply. The findings of the report, “High mountain glaciers and climate change” were announced during the UN climate meetings in Cancun, where negotiators are working towards an agreement to reduce climate emissions.
The new UNEP data underlines the urgent need for climate action that will produce quick results – a topic addressed by a separate event today in Cancun, hosted by UNEP and the Federated States of Micronesia, a country calling for a fast-action work program to protect its low-lying islands and other vulnerable countries from climate change impacts.
The panel of scientists and policymakers, including UNEP Executive Director, Achim Steiner, and Mexican Nobel Laureate Mario Molina, emphasized the need to address non-CO2 climate forcers like black carbon soot, methane, tropospheric ozone, and HFCs to achieve fast mitigation.
Black carbon, a particulate aerosol produced from incomplete combustion of fossil fuels and biomass burning, directly contributes to glacial melt by settling on snow and ice, which darkens the surface and then absorbs the heat instead of reflecting it.
“The Himalayan glaciers are the main freshwater source for hundreds of millions of people across several countries,” said Durwood Zaelke, President of the Institute for Governance & Sustainable Development. “Fast mitigation of black carbon soot and other non-CO2 forces are the best hope to avert disaster.”
Because these non-CO2 climate warming agents are short-lived in the atmosphere compared to CO2, which can remain for hundreds to thousands of years, reducing them can buy critical time to make aggressive cuts in CO2 emissions.
Added Zaelke, whose organization focuses on the non-CO2 issue and is attending the meetings in Mexico: “Reducing CO2 is essential and we can’t lose that focus, but these are complementary measures that are within easy reach. We would be guilty of Planetary malpractice to waste this opportunity.”
Achim Steiner stated that reducing the non-CO2 forcers “can buy back some of the time” the world has wasted by not addressing CO2 earlier.
It seems that embarrassment over the typo in AR4 WG2 has not slowed the Himalayan glacial retreat. I am, at this point, not sure what the time scale is for disruption of Asia’s major rivers. I suppose AR5 will be reliable on that, there’s one saving grace!
Anyway, Ray is quite right on the big big picture. I’m not going to criticize Ray on the science, not being a complete fool(*).
But as I see it getting through the bottleneck centuries is the real trick. And the less climate stress in the short run, the better. CO2 reduction is absolutely crucial but it has little short run payoff. I am not saying our distant descendants (if any) won’t have quite a gripe against us. I think though that their gripe will be bigger the more spectacularly we drop the ball.
* Note: criticizing Ray Pierrehumbert on science does not ipso facto make you a complete fool. Criticizing him directly on climate science after hanging around him for a few years in a scientific setting, however, makes you either something of a fool or something of a climate science genius. I’m neither.