17 Jan, 2012 NATS 1880
-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?
-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
-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
-Use (Annual) ice-core measurements to search for historical CO2 concentrations
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
-Evidence for a good correlation periods of higher Co2 concentration also are periods of higher
-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)
-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