Lecture11_2011 - Glaciers Sea ice Northern Hemisphere...

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Unformatted text preview: Glaciers Sea ice Northern Hemisphere during the Last Glacial Maximum 20,000 yrs ago Pics From NOAA Paleoclimate web page What is required to build an icesheet? IPCC Chapter 4 Summary of observed changes in the cryosphere IPCC report highlighted shortcomings in sea-level rise predictions for ice sheets Current models do not “include the effects of changes in ice sheet flow, because a basis in published work is lacking… understanding of [rapid dynamical changes in ice flow] is too limited to assess their likelihood or provide a best estimate or an upper bound for sea-level rise” Total contribution to sea-level rise from Antarctica and Greenland together contain ~70m global sea-level equivalent Antarctic Ice Sheet system Current and future changes in the ice sheets result from a complex function of accumulation, melting and ice dynamics Predicting the future requires careful incorporation of processes into ice sheet models – boundary conditions are critical Where are the boundaries? Calving front Grounding zone Ice shelf base Ice-rock interface Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond (a.k.a. NRC Decadal Survey) Key Question #1 (of 6): “Will there be catastrophic collapse of the major ice sheets, including Greenland and West Antarctica and, if so, how rapidly will this occur? What will be the time patterns of sea level rise as a result?” Sierra Snow pack regulates discharge so water is delivered when most needed also helps recharge groundwater because snow melts slowly Infiltration purifies water and traps inpurities Wells depress water table http://images.google.com/imgres?imgurl=http:// techalive.mtu.edu/meec/module04/images/ GroundwaterSpeed.jpg&imgrefurl=http://techalive.mtu.edu/ meec/module04/ GroundwaterSpeed.htm&h=345&w=531&sz=48&hl=en&start= 9&um=1&tbnid=T7ChTlA1aHrXsM:&tbnh=86&tbnw Keeling Curve - Scripps Greenland (= 6 m of sea level) is thinning now and disappeared during the last Interglacial Climatic Impact on Seascapes and Landscapes 6 m eustatic sea level rise West Antarctica more susceptible to ablation because of ice shelves 60 m eustatic sea level rise Global Dimming CO2 Emissions 2-3 mm/yr rise in sea level What does δO18 tell us about climate? 1. Reservoir 2. Temperature What causes the different sea level fluctuations - why is it not equivalent around the world (eustatically)? ...
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This note was uploaded on 03/23/2012 for the course SIO 35 taught by Professor Driscoll,n during the Winter '08 term at UCSD.

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