Global Issues Global Warming EPA Site covers most of the global climate change Ozone Depletion

The Atmosphere Four distinct zones –Temperature –Relative gas concentrations –Pressure Troposphere: 75% of total mass –5 to 10 miles –What happens to temperature? Stratosphere: to about 31 miles –Low water vapor; ozone 1000x higher than troposphere –What is source and importance of ozone? –Ionosphere

Solar Radiation How much reaches the earth’s surface? Selective absorption in the atmosphere –Visible light –Ultraviolet –Infrared Albedo –Snow vs. a dark surface –Average earth’s is 5% (due to oceans)

Earth’s Radiation All energy absorbed by surface is reradiated But… how is this different than incoming? Reradiated as infrared vs. incoming visible light So What? What gasses absorb infrared?

Climate and Climatic Catastrophes Climate vs. weather Gradual climatic change: adaptation, evolution Abrupt climatic change: mass extinctions –65 million years ago (end of Cretaceous) –Up to dozen such great climatic changes What is the evidence of past climatic changes? Developing models for future changes

Some Numbers - Temperatures  Global temperature increase, : 1.25° F or about 0.8 degrees C  Rate of temperature increase since 1990: 0.72° F or 0.5 degrees C.  IPCC's estimate of global temperature increase by 2100: 2.5° F ° F  Temperature increase in the Arctic since 1970: 4° F  Average temperature on Earth, with moderate greenhouse effect: 59° F

Some Numbers - Carbon  Quantity of CO2 in the atmosphere before the industrial revolution: 288 parts per million  Quantity of CO2 in the atmosphere in 2000: 370 parts per million Years since Earth's CO2 level was last this high: 20 million Annual increase of CO2 in the atmosphere: 1.5 parts per  % of the enhanced greenhouse effect caused by CO2 52.5% % of the enhanced greenhouse effect caused by methane: 17.3% % of the enhanced greenhouse effect caused by ozone: 12.5%

Some Numbers -  Global temperature increase, : 1.25° F or about 0.8 degrees C, most in the last 40 years  Rate of temperature increase since 1990: 0.72° F or 0.5 degrees C.  IPCC's estimate of global temperature increase by 2100: 2.5° F ° F ( deg C)  Temperature increase in the Arctic since 1970: 4° F  Data source: IPCC report (over 2000 leading climatologists)– and, US National Academy of Sciences  Videos with some data Videos with some data  NOAA data and graphs NOAA data and graphs

Carbon Dioxide Concentrations Annual increase of 0.5% Twice pre-industrial concentrations by 2100 What are the sources?

Other Greenhouse Gasses Methane –Absorbs 20x to 30x as much heat as CO 2 –Accumulating 2x as fast as CO 2 –Ruminant animals, coal mines, pipeline leaks, landfills Chlorofluorocarbons (CFCs)

Effects of Climatic Change Temperatures –Middle and high latitudes much indrease Precipitation –High latitudes wetter –Mid latitudes drier Rising sea levels (appear to be increasing 2mm/year) Continental glaciers may melt - coastlines inundated

Can CO 2 Emissions be Reduced? Earth Summit-1992-Industrialized nations reduce to 1990 emissions by 2000 Kyoto Protocol : industrialized nations –Average 5.2% below 1990 by 2012 –How to enforce? No penalties U.S.: Wants to trade emission quotas –Forest replanting would equate to emission controls

Can CO 2 Emissions be Reduced? Kyoto Protocol : industrialized nations –Average 5.2% below 1990 by 2012 –Has this been ratified? –What was U.S. opposition –How to enforce? No penalties IPCC Report: summary of the reportIPCC Report:

Can CO 2 Emissions be Reduced? IPCC Report: summary of the reportIPCC Report: Cap and Trade –( trading emission allowances)Cap and Trade –( trading emission allowances)

Critical Thinking - What To Do? How certain should we be before acting? What are the potential economic consequences (of taking or not taking action)? Should developing countries be forced to remain at or near current levels? Are there potential positives if we cut emissions even if the models are overly pessimistic? What will happen if we don’t act?

El Nino La Nina- Trade winds move ocean surface currents westward –Thermocline –Upwelling of waters west of S.A. El Nino –Indonesian Low Collapses; warm water moves east –Jet stream drawn south- moist air drawn from Gulf and Pacific –Are El Nino years becoming more frequent?

Ozone Depletion First detected “ozone hole” over Antarctica in : all ozone over Antarctica between 14 and 20 km destroyed Danger: more UV rays –1% decrease in ozone results in 2% increase in UV equals 1 million more skin cancers

Why is Ozone Being Depleted Antarctica - unique weather conditions CFC - Freon- a great refrigerant - Why? Propellants in aerosols - A What?? No longer propellants Helsinki Agreement (1989) - phasing out of all uses of CFC’s