The Weekly Carboholic: Study says dams reduced sea level rise

Posted on April 16, 2008

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carboholic

hooverdam.jpg
Image Source: US Bureau of Reclamation

Dams exist to store massive amounts of water, water that may be used for flood control, irrigation, human consumption, or even electricity generation. And dams are very, very good at storing water. So good, in fact, that a new study from Taiwan’s National Central University says that dams slowed sea level rise over the 20th century. From the Nature blurb about the story:

By damming rivers, humans have masked the full extent of surging sea levels, a new study finds. Sea levels have risen by an average of 16 centimetres since 1930, and they would have risen by an additional three centimeteres but for the water tucked away in manmade reservoirs last century, not carefully tallied until now.


As a result, the paper’s abstract says “[t]his demands a considerably larger contribution to GSL rise from other (natural and anthropogenic) causes than otherwise required.” In other words, the approximately 10,800 cubic kilometers of water that wasn’t added to the oceans in the last century would have resulted in sea level increases that were 19% more than what actually occurred (16 cm actual, 19 cm with dammed water included), and so most sea level models are underestimating the amount of sea level rise that will occur this century.

Unless, that is, we accept the environmental trade offs inherent in the construction of massive dams.

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Supposedly, the reason that Al Gore used a photo of a massive hurricane coming out of a smokestack for the cover of An Inconvenient Truth was that he was impressed by the claims of MIT atmospheric scientist Kerry Emanuel, who claimed that global heating would drive larger and stronger tropical cyclones (known as hurricanes in the Atlantic ocean). His prediction seemed prescient when Katrina hit New Orleans a few weeks later. However, there has always been some controversy regarding Emanuel’s claim, given that global heating is expected to strengthen the forces that disrupt cyclones too. And now, the Christian Science Monitor reports that Emanuel’s team have developed new hurricane model that appears to contradict his prior conclusions.

Cyclones are fundamentally powered by hot water – the hotter the ocean is beneath them, the more powerful the cyclone can become. And Emanuel’s 2005 research concluded that, since global heating was going to result in much hotter oceans, more powerful cyclones would be the result. Completely logical. But there are forces that work to limit the power of a cyclone too, such as high altitude wind shear (winds that create the anvil-shape of thunderstorms), and wind shear has also been predicted to increase with global heating. As such, the predictions for cyclones have been less than conclusive.

Emanuel’s new models still predict a 20% increase over present cyclone activity – in 2200 – but nothing like the 50% increase observed since 1980 (and reconstructed using Emanuel’s new models). However, while overall frequency of cyclones doesn’t increase as dramatically as Emanuel predicted in 2005, the models still predict that warmer oceans lead to larger, stronger, and more destructive cyclones, just not quite as many of them as prior predictions. And, given the contradictions, Emanuel’s team is working to better understand why the new models are not predicting the same effects as previously.

Either way, though, buying Atlantic coastal property is going to be a risky proposition for the foreseeable future.

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Scientific American reported last week that researchers at the Center for Catalysis Research at RWTH Aachen University in Germany are working on a method to convert captured carbon dioxide into tough polycarbonate plastic under pressure and with additional energy. Unfortunately, there’s a catch – the process requires a significant amount of energy, and at the moment, that means more carbon dioxide emitted for every polycarbonate CD or DVD made out thin air.

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According to the Edmonton Journal, the Redwater geological reef may be used both to store billions of tons of CO2, and in the process the carbon dioxide captured from nearby industrial carbon sources (such as a tar sands processing facility) may be used to extract more premium light oil from the deposit in the reef. According to the article, ARC Resources Ltd. and the Alberta Research Council believe that the reef is well suited to CO2 storage because the hard cap rock over the oil deposit that kept the oil isolated should be impermeable enough to prevent CO2 leakage out of the formation.

This is a great partial solution to the carbon problem, especially for Canadian tar sands operations. It not only pushes out peak oil, improves energy security, and extend the life of a valuable oil deposit, but it also enables the semi-permanent storage of a lot of carbon dioxide. The main problem here is that it extends the use of fossil fuels, something that will ultimately need to end if we hope to ever decarbonize human civilization.

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