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17th Jan,2012 (NATS 1880) Global Warming.docx

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York University
Natural Science
NATS 1880
Paul Delaney

17 Jan, 2012 NATS 1880 Global Warming -Earth’s average temperatures are currently on the rise -Topic with a great deal of controversy (esp political) -Is it a natural phenomenon or the result of human activity? -Should something be done about tit and if so how much? Evidence -CO2 is a greenhouse gas and human activity is enchaing its concentration -We must determine temperatures accurately on global scales - Must be well calibrated when comparing over time. -Image shows the surface temperature from 1951-1981. Shows changes in the average surface temperature. -Orange, Dark red are much above average -Dark Red and Orange is mostly regions near to the arctic regions. 90% of the ice is in Antartica. Changing the temp can melt the ice and sea levels will rise. Satellite data and ocean temp provide helpful data Before satellite , temp more difficult to estimate. -There are many reason for local temp changes. There are natural climate cycles ( long period changes of Earth) -Local changes can happen for a variety of reasons -Global averages increased by 0.8 C in past century -Most of this warming , 0.6 C occurred in past 30 years -This increase can be larger / smaller depending on the location -Polar Regions (glaciers) are warming much more than other regions. -Calibration is important to make sure they read the same temperature at same time. -Warming and Increased CO2 -Companies saw the cause of smoking & its effect -Large samples, statistical methods to show correlation -Causal relation -Use (Annual) ice-core measurements to search for historical CO2 concentrations -Diagrams Bottom (cycles becoz those are natural -Correlation = peaks and valleys occur Top diagram: TEMPERATURE -They correlate but that doesn’t mean they CAUSE it, there might be more factors involved Annual CO2 change. -Trend is up -Causation -Evidence for a good correlation periods of higher Co2 concentration also are periods of higher average temp. -Have been temp swings of 10C in Earth’s History -NASA map (aqual AIRS map) -It measures CO2 Concentration -Troposphere : lower component of the atmosphere upto about 15-20km (where we live) Global Warming Models & Uncertainties -In the end, the critical questions are whether the CO2 warming correlation is causally related and whether warming is man –made(ANTHROPOGENIC) -Nuclear Winter -For such a short time scales (centuries ) require computer climate modelling -Jaguar XT5 Supercomputer designed for climate modelling -Exceedingly complex problem -Models are very sophisticated -Can now match Graph = Change in the temperature -Black are observations (show rise in avera
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