Climate Change Chapter 3 PDF

Troposphere  Where weather happens  Location - surface to about 10 km.  Composition - unpolluted air: Nitrogen (78%) Oxygen (21%). Remaining 1% is CO2 (0.0365%), H, He, Ar.  Water vapor is an additional variable amount,.01% to 5%. Stratosphere  Where jets fly (at the bottom of it)  Loc...

Troposphere  Where weather happens  Location - surface to about 10 km.  Composition - unpolluted air: Nitrogen (78%) Oxygen (21%). Remaining 1% is CO2 (0.0365%), H, He, Ar.  Water vapor is an additional variable amount,.01% to 5%. Stratosphere  Where jets fly (at the bottom of it)  Location - Above troposphere, about 10-50 km. Very thin air - virtually no weather, and no turbulence.  Composition- Similar to troposphere, except  water vapor is 1000 x less  ozone is 1000 x greater. Climate and Weather  Climate = long-term atmospheric conditions  Weather = short-term atmospheric conditions  Both climate and weather are dynamic – they change with time CO2 measurements  Evidence for Climate Change 1. 20th C was hottest in the past 1000 years 2. Global temp has risen 0.6°C (1.1°F) since 1861 3. 16 warmest years on record since 1980, 10 warmest since 1990 4. Glaciers and sea ice are melting 5. Sea level has risen 100-200 cm over 20th C Projecting Future Changes in Earth’s Climate We can’t do real experiments on the whole earth’s climate, so how do we predict future climate change?  Scale up from small experiments  Computer models (GCMs)  Learn from the past  Paleoclimatology and Paleoecology (climatology) Solutions: Dealing with the Threat of Climate Change Options  Do more research before acting – “wait and see” (current US strategy)  Act now to reduce risks because global warming would have severe impacts  Act now in same way to reduce risks of global warming because it has other benefits to environment and society (even if warming doesn’t happen) Removing CO2 from the Atmosphere  Reducing Greenhouse Gas Emissions  1988 - Intergovernmental Panel on Climate Change (IPCC) established, body of scientists advising UN on climate change  1997 - Representatives of 161 nations met in Kyoto, Japan for a UN meeting on climate change  Kyoto Protocol - agreement reached during meeting to reduce CO2 emissions from 39 developed countries to 5.2% below 1990 levels by 2012.  2001 US pulled out of the agreement.  Russia’s recent ratification was enough for the Kyoto Protocol to take effect.  Will there be a new post-Kyoto treaty? Ozone in the Stratosphere: the “Ozone hole”  Ozone (O3) in the stratosphere protects life on the surface of the earth from harmful UV solar radiation. CFCs  Chlorofluorocarbons (CFCs) and related chemicals break down ozone in stratosphere  Uses (mostly phased out) Air Conditioners Refrigerators Spray cans Cleaners for electronic parts Sterilizing medical instruments Fumigants for granaries and cargo ships Seasonal Ozone Layer Thinning at the Poles Credit: © Science VU/NASA/Visuals Unlimited Loss of the Ozone Layer: Reasons for Concern  Increased incidence and severity of sunburn  Increase in eye cataracts  Increased incidence of skin cancer  Immune system suppression  Increase in acid deposition  Lower crop yields and decline in productivity Solutions: Protecting the Ozone Layer  CFC substitutes  Montreal Protocol 1987  Copenhagen Protocol 1992 both signed by 177 countries  CFCs take 10-20 years to get to the stratosphere  CFCs take 65-385 years to break down  Global average temperature and sea-level are projected to rise under all IPCC scenarios Temperature: +1.4 to +5.8 °C (between 1990 and 2100) Snow and Ice cover: decreases, but Antarctica gains mass (W. Antarctic Ice Sheet stable); Greenland loses ice. Sea level: +9 to +88 cm ; thermal expansion mainly Anthropogenic climate change will persist for many centuries