Planetary Atmospheres, the Environment and Life (ExCos2Y) Topic 9: Climate Change Chris Parkes Rm 455 Kelvin Building

8. Storm systems Storm Systems –Hurricanes Formation Structure –Tornados Formation –Dust Devils, Water Spouts Revision

Climate Change Many forms discussed in lectures:

Earth’s Long-Term Future Climate Remained suitable for life for 4 billion years –Feedback mechanisms Sun will continue to warm –Life on Earth ultimately doomed –Loose water > 1 billion years from now –CO2 cycle may provide regulation for longer –Life < 4 billion years Earth will become like venus –1to 4 billion years –More pressing worries….

Climate Conditions for Human Life Planets geology and biology: Pressure, Temperature – liquid water Oxygen – right amount in atmosphere Ozone Layer – absorbs UV Magnetospheres – deflects solar wind Human Effects: Ozone depletion – now correcting Extinction of species Global warming

Temperature increased by 0.5 o in last 50 years Burning fossil fuels adds CO 2 to atmosphere –Concentration significantly higher than in 600,000 years Greenhouse mechanism well understood

Global Warming Effects on climate dependent on feedback mechanisms –Temperature rise leads to more water evaporation –Water vapour acts as greenhouse gas increases temperature –Water vapour forms clouds, reflect more decreases temperature –Temperature rise melts ice –Ice highly reflective, water highly absorbsant Increases temperature And raises sea levels – flooding Effects on Forests, Eco-systems: –food production, fresh water

Potential Effects of Global temperature rise Glacial Retreat Arctic Shrinkage Sea Level rise Change in ocean currents More Intense Hurricanes /extreme weather events Changes in eco-systems

Glacier melting / ice caps / lakes Retreats of glaciers World Glacier Monitoring Service

Sea level Melting glacier ice gives sea rise –Melting sea ice does not (as floating) Contributes further to global warming through albedo Potential for flooding major areas of population Predictions IPCC

Fossil CO 2 emissions

Climate change in the past Source T. Stocker ppm (380 ppm in 2007, 330 ppm in 1974) (Can extend graph to 850'000, T. Stocker 2006) Homo Sapiens appears Agriculture begins Ice Core Data – gives temperature from heavy water (deuterium D) CO2 levels – high correlation Deuterium=Temperature CO 2

Climate change in the present

Quality of climate models Reasonable agreement of models and measured temperatures over past data

Projections Range of climate models Assuming no special action taken

Example exam questions Q1. What are the potential Effects of Global Warming ? Q2. How do we obtain long time scale data on previous CO 2 levels and temperatures ? Q3. How does global warming and changes in the Earth’s albedo interact ?