Lecture 19

Lecture 19 - SIO 40 Life and Climate on Earth Nov. 16, 2009...

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Unformatted text preview: SIO 40 Life and Climate on Earth Nov. 16, 2009 Lecture 20 Impacts of Climate Change Lecture Outline- Areas of impact- Sea level rise- Global warming and biodiversity- Changes in water resources- Food resources- Human health- Arctic impacts lobal warming impact summary from the IPCC AR4 Global warming is projected to apply stresses to human societies and ecosystems in a variety of ways. Rising sea level areas at risk http://www.globalwarmingart.com/sealevel 10% of the worlds population lives in coastal and low- lying areas where the elevation is within 10 m of sea level. Rising sea level, increased destruction associated with tropical storms, increasing coastal erosion, and larger wave heights all pose serious threats to coastal and low-lying regions. Areas shown here which are at particular risk include Florida and the Gulf coast of the US (left), Belgium and the Netherlands in Europe (below left) and Bangladesh (below right). Potential long-term impacts of sea level rise Although communities, habitats, and economies on all of the major continents will be affected by even just 1 m of sea level rise, costs rise dramatically at 5 m and 10 m. The melting of the Greenland ice cap will likely lead to 5-6 m of sea level rise, and the West Antarctic ice sheet would result in an extra 5 m. Although it will take several centuries for complete melting of these ice caps, irreversible melting could conceivably be set in motion by the end of this century. Patterns of sea-level rise While we anticipate that sea level will rise due to global warming, the rise will not be uniform across the oceans. The actual pattern of sea level rise will depend on a number of factors. One factor is regional changes in Earths gravity field that will accompany changes in continental ice sheet mass due to melting. Such changes will impart a geographical fingerprint to the rise in sea level expected for the melting of the West Antarctic Ice Sheet, for example (top left), with the greatest sea level rise occurring (perhaps unexpectedly) in the Northern Hemisphere. Also, changes in ocean circulation expected to accompany global warming will affect sea level differently in different regions. Slowing of the North Atlantic Conveyor Belt circulation is expected to cause an increase in sea surface height in the vicinity of the northeast coast of the United States (lower left), making New York City especially vulnerable to additional sea level increases as a result of ice sheet mass balance changes. regional change in sea level, meters Biodiversity and climate change The IPCC report states with medium confidence that 20-30% of plants and animals will be subject to increased risk of extinction if global temperatures rise to 2 C above the pre-industrial level and perhaps 40-70% of species will be at risk of extinction if temperatures rise by 4 C. These temperature changes are well within the range of reasonable projected possibilities. 5 major extinctions in the last 500 million years.5 major extinctions in the last 500 million years....
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This note was uploaded on 10/23/2010 for the course SIO SIO 40 taught by Professor Barbeau during the Fall '10 term at UCSD.

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Lecture 19 - SIO 40 Life and Climate on Earth Nov. 16, 2009...

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