Predicting Global WarmingSlide 2Slide 3How to Make Climate Predictions ?Slide 5Some Modeling Problems:GCM’s: The Hard-Core ApproachSlide 8Slide 9Slide 10Slide 11“Low-Tech” ApproachSlide 13Comparison of two ApproachesResults of Climate ModelsResults of Climate ModelingSlide 17So, who cares ?the underlying problem…population growth ratesPredicting Global WarmingENVS 110 (02-14-08)Source: Commonwealth of Australia 2006, Bureau of Meteorology (ABN 92 637 533 532)http://www.bom.gov.au/climate/current/soi2.shtml (accessed 3/13/06)http://www.cpc.noaa.gov/products/predictions/multi_season/13_seasonal_outlooks/color/page2.gifHow to Make Climate Predictions ?•Climate Models–very simple energy balance models–more complicated general circulation models (GCM’s)–what to include–what to leave out–how do feedback’s workSome Modeling Problems:•generally low level of scientific understanding•timescales involved•high spatial resolution required to obtain “useful” results•computationally expensiveGCM’s: The Hard-Core Approachsource:Hadley Center, The MET Office“Low-Tech” Approach•make very few assumptions about importance of forcings and feedbacks•keep the math simple (relatively speaking)•fast model, can do many runs, try many things•can pick “best” result•how to decide on “best” result?source:Knuti et al., nature 2002Comparison of two ApproachesResults of Climate Models•all models predict a rise in temperature due to an increase in atmospheric CO2•increase most severe in high latitudes–melting of polar ice caps–sea level rise–global cooling ?•changes in precipitation, soil moistureResults of Climate ModelingFrom Mitchell et al., 2001http://www.ucar.edu/news/releases/2006/ibm.shtmlSo, who cares ?•societal concerns (economic hardship)•ecological concerns (survival of other species, ecosystems – why is this a problem ?)•ethical concerns(who will be affected the most?)is global warming by definition a bad thing?the underlying problem…http://www.sustainablescale.org/AreasofConcern/Population/PopulationandScale/QuickFacts.aspxpopulation growth