I’ve read a number of articles and abstracts from research papers on climate change-related topics. I’m going to provide a quick overview for some of them in a couple of posts, starting with this one. What I’ve found indicates to me that the legislation now going through the House Energy and Commerce Committee is severely lacking in one arena it is supposed to address: reduction of near- and long-term greenhouse forcing, most notably by reducing carbon emissions. It is unfortunate that politicians are not only mostly unaware of this and other recent research, but too many are willfully ignorant of the state of the science as of May 2009.
The first is “Overshooting convection in tropical cyclones” by David Romps and Zhiming Zhang. They looked into the role that tropical cyclones play in injecting water vapor into the stratosphere via deep convective towers. Water vapor in the stratosphere has elsewhere been shown to raise surface temperatures slightly due to their interaction with sunlight. With forecasts of an increase in tropical storm number and activity as one result of anthropogenic climate forcing, a positive feedback could be established by the cyclones. The authors rightfully acknowledge that interpretation of their results isn’t without complications. They point out that the tropopause could be lifted by these intense tropical cyclones and that water vapor may not be injected into the stratosphere with every occurrence of a cyclone. Even if little of this makes sense, I highly recommend taking a short trip to Romps’ webpage where he has an animation of tropical activity for 2005 – a very active year in the Atlantic basin. Don’t overlook the activity in the western Pacific or Indian Oceans, however.
Geoengineering is receiving a lot of interest in the scientific community. A paper was written a few months back that compared a number of different geoengineering proposals’ theoretical effectiveness. Some take-away findings: Enhancing carbon sinks could bring CO2 back to its pre-industrial level, but not before 2100 – and only when combined with strong mitigation of CO2 emissions. Stratospheric aerosol injections and sunshades in space have by far the greatest potential to cool the climate by 2050 – but also carry the greatest risk. Indeed, sulfate injections into the stratosphere is one of the most proposed plans due to its potential effectiveness. Eventually, however, sulfates would fall through the troposphere and mix with chemicals there to fall as sulfuric-acid – something that would harm vegetation as well as sea life. We’re geoengineering the atmosphere now. I don’t feel confident that new, large-scale efforts would fix the problems we have without raising ones we’re not prepared to deal with. The best way to deal with climate forcing is to stop the forcing.
Along those lines, one study did investigate some of the effects of reducing solar input as a geoengineering approach. Doing so would eventually reduce surface temperatures as much as reducing CO2 forcing would. At the same time, global precipitation would be reduced at a higher rate. That is, if solar reflectors in space or aerosols in the atmosphere were to be introduced, the global water cycle would slow down faster than global temperatures would. Govindasamy Bala, the lead on the study, pointed out what I mentioned above, then went a step further:
sunshade geoengineering would not limit the amount of CO2 emissions. CO2 effects on ocean chemistry, specifically, could have harmful consequences for marine biota because of ocean acidification, which is not mitigated by geoengineering schemes.
Geoengineering only deals with part of the problem. There are interdependent processes at work, all of which must be investigated across a range of proposals. Only then will we have a robust idea of what path to take. In my opinion, reducing the CO2 forcing is the most straightforward solution. It’s what led to the problems we’re facing and considering. Tinkering with the effects doesn’t get at the cause.
The Arctic Treeline Advance study is investigating how climate change and arctic ecosystems are interacting. This is the summary of the hypothesis being tested:
“The general expectation is increased growth and reproduction as a result of warming climate that causes the treeline to simply expand beyond where it is currently found, both further north, and higher up on mountains,” says Dr. Starzomski. “So, the treeline expands. Darker trees absorb more solar radiation, leading to more warming. This leads to further expansion and the creation of a positive feedback cycle.”
Disappearing sea ice in the summer and darker landmass cover means the Arctic will continue to warm more than the rest of the globe, if studies like this confirm scientists’ suspicions.
The last paper I’ll mention here is entitled, “Lifetime of Anthropogenic Climate Change: Millennial Time-scales of Potential CO2 and Surface Temperature Perturbations“. I will likely have more to say on this paper in the future as I haven’t finished reading it yet, but the high-level message it delivers is the following. The time required to absorb anthropogenic CO2 strongly depends on the total amount of future emissions. (There shouldn’t be anything surprising about that statement – it takes geologic time to scrub excess CO2 from the atmosphere.) If known fossil fuel reserves are burned, the time to absorb 50% of the resultant CO2 is more than 2,000 years. Now for the really bad news: the long-term climate response appears to be independent of the rate at which CO2 is emitted over the next few centuries. That climate response has already largely been locked into place. That’s because the time scale at which atmospheric temperature declines will be much longer (60%!) than the time scale for the absorption of CO2. If we completely stopped emitting CO2 tomorrow, temperatures would continue to climb for hundreds of years because of the forcing already in the system. The study reports that 2/3 of the maximum temperature anomaly may persist for longer than 10,000 years.
Politicians in Washington D.C. are more interested in doing the bidding of the dirty fossil fuel industry than looking out for humanity’s well-being for the next 10,000 years. As I’ve written before, it all boils down to who’s being affected by the problem. Unfortunately, it looks like many more people are going to have to face the direct impacts of climate change before politicians respond with intelligent climate policy. By then, I fear it will be too late. Instead of relatively cheap mitigation policies, they’ll have to enact incredibly expensive adaptation policies including relocating substantial numbers of people and deciding what part of our infrastructure is saved and what is not.
Cross-posted at SquareState.