Wednesday, August 29, 2007

The Undertaking

The reason, I think, that people get so infuriated with James Hansen is that he has such a long track record of being right much sooner than other people. He's the kid in class who gets the answer not only first, but right away, no sweat. He's also the kid who just blurts out the correct answer without being called on. So, people like the President attempt to censor him and there is a great roaring on the internet when some data published on the web has an unimportant flaw (see he's not perfect).

So, here comes another flap. A newspaper article has misquoted a new paper by Hansen and co-workers saying that they are predicting 25 meters of sea level rise by the end of the century. And, a number of blogs are cranking up the ridicule. But, if you read the paper you'll see that they predict 25 meters in centuries, not this century. This is still important because it is not 25 meters in a thousand years, but you end up with several meters by the end of this century, not 25 meters.

Let's work backwards in the paper because there is some really big new at the end that the newspaper article missed. First the last footnote:

The potential of these 'amber waves of grain' and coastal facilities for permanent underground storage 'from sea to shining sea' to help restore America's technical prowess, moral authority and prestige, for the sake of our children and grandchildren, in the course of helping to solve the climate problem, has not escaped our attention.

Back in the day, colorful footnotes used to set apart some of the better academic writers but you don't run into these as often now. The footnote is about a scheme to sequester carbon dioxide from the atmosphere by burning plants to make electricity and then squirting the carbon dioxide down below the bottom of the ocean where it should stay put. The big news is not about the particular scheme, which is a little awkward, but that they are discussing sequestration at all. This is a big departure because up until now Hansen has been saying that there is likely a decade or so over which we might simply reduce emissions and thus avoid a large sea level rise. Sequestration is likely to be more expensive than just reducing emissions. The cost to build a coal plant that captures carbon dioxide for sequestration is about $2.20/Watt while thin film photovoltaic panels are being manufactured now at a cost of $1.19/Watt. So, where we would be saving money by reducing emissions, adding on a requirement to clean up the mess we've made already through technological intervention could add to our costs. There is a large prize being offered to figure out how to do large scale sequestration and make money too so it may turn out that we'll learn that sequestration saves money as well, but so far, adding sequestration to a coal plant looks as though it adds about 40% to the cost of building a plant. For a biofuel plant there may be similar costs and since the methods we know to get photosynthesis to scale up to our energy use involve needing a source of concentrated carbon dioxide, a sequestration plan based on burning grasses won't have a big impact on the atmospheric CO2 concentration even though growing grasses does help. Biological methods to sequester carbon dioxide from the atmosphere, if needed at scale, probably have to occur in the oceans though the potential of coastal regions to support much more mineralization should not be overlooked. At a guess though, since we are seeing so much progress in shifting from thermodynamic to quantum means of generating electricity, a technological approach to sequestration of carbon dioxide from the atmosphere will leverage the very low cost of electricity and high availability of energy we can anticipate to use chemical sorbants that can absorb carbon dioxide from the atmosphere much faster than plants can so that we minimize the land use impacts of our clean up effort.

Again, the big news is that Hansen is calling for sequestration of carbon dioxide out of the atmosphere rather than what particular method is given as an example. So, why the change? Let's keep working backwards:

The best chance for averting ice sheet disintegration seems to be intense simultaneous efforts to reduce both CO2 emissions and non-CO2 climate forcings. As mentioned above, there are multiple benefits from such actions. However, even with such actions, it is probable that the dangerous level of atmospheric GHGs will be passed, at least temporarily. We have presented evidence (Hansen et al. 2006b) that the dangerous level of CO2 can be no more than approximately 450 ppm. Our present discussion, including the conclusion that slow feedbacks (ice, vegetation and GHG) can come into play on century time-scales or sooner, makes it probable that the dangerous level is even lower.

This is it, we won't go farther though the paper seems virtuosic. They find no evidence that ice sheets linger once the temperature goes up when they examine big climate changes in the past. That makes changes in ice cover and plant cover into an additional feedback that boosts warming on a shorter time-scale than usually assumed. This puts us in a position where just reducing carbon dioxide emissions as quickly as we can may not be enough. The solution to global warming would then involve reversing it, not just ending it. And, this is why the position has changed.

Change sounds like just what we may be needing to lay on the eyes of the ghosts we have dug up to ferry them back where they belong. All the more reason to get real about energy so we can save our pennies for the task ahead.

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