SIO40lecture23

SIO40lecture23 - SIO 40 Life and Climate on Earth Nov. 29,...

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SIO 40 – Life and Climate on Earth Nov. 29, 2010 Lecture 23 – Mitigating global warming, Part I Geo-engineering approaches
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Geo-engineering Solutions (?) Geo-engineering is an approach to mitigating global warming that involves using technology to counteract climate change impacts either at the source level (eg. trapping CO 2 emissions before they get into the atmosphere) or at the impact level (eg. reducing the amount of solar radiation reaching the Earth). These approaches involve planetary-scale environmental engineering, the likes of which society has not yet seen.
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Recommended Reading and Viewing http://www.economist.com/node/17414216 http://www.youtube.com/watch?v=VmOtjM9XPS E&feature=player_embedded
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Preliminary assessment of various proposed geoengineering approaches published in a report by The Royal Society, London, in 2009.
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The idea of purposely injecting sulfur dioxide into the stratosphere to cool the planet is based on the knowledge that volcanic injection of SO 2 into the stratosphere (above left) results in the formation of sulfate aerosols which can reduce transmission of solar radiation through the atmosphere (above right). Stratospheric aerosols: Would it work? We already have some data…. .
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Global mean temperature changes for 5 years preceding and following a large volcanic eruption (at year zero). Data are average changes noted for 5 major eruptions: Krakatau, Santa Maria, Katmai, Agung, and El Chicon. These averages suggest a global cooling of 0.3-0.7 ° C for 1-3 years following an eruption. Cooling due to volcanic eruptions
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Concerns about sulfate aerosol addition While aerosols themselves do not destroy ozone, interaction of aerosols with chlorine in the stratosphere due to CFC’s can have a detrimental effect on ozone levels, as observed following the eruption of Mt. Pinatubo (above). Some worry that purposeful addition of sulfate aerosols to the atmosphere to counteract global warming could have unforseen negative effects on ozone. Other concerns relate to acid rain and unpredictable shifts in rainfall caused by the aerosol addition, which could adversely affect climate in some regions.
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Some geo-engineering schemes are targeted at increasing Earth’s overall albedo, thus reflecting more solar energy back into space rather than absorbing it. One such idea, pictured above, would involve fleets of up to 1500 ships that would cruise the oceans, sucking up seawater and spraying it into the lower atmosphere. This would increase cloud albedo over the oceans. Other ideas related to albedo include wrapping reflective “blankets” around glaciers, or floating reflective surfaces over large areas of the oceans.
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SIO40lecture23 - SIO 40 Life and Climate on Earth Nov. 29,...

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