Atmospheric Changes Resulting From Human Activities Factors that contribute to global warming. Possible climatic impacts of global warming. Factors that contribute to loss of the ozone shield. Possible impacts of UV light penetration. Atmospheric Pollution: Acid Rain

Atmospheric Structure Jet Streams 300 mph

Climate Defined as the average trend in temperature and rainfall that produces a unique assemblage of plants and animals. Climate is modulated by differential solar radiation, which established major atmospheric circulation patterns. The polar regions are areas of net heat loss. Atmospheric circulation and ocean circulation distribute solar energy input as heat from the tropics and temperate latitudes to the poles.

Oceanic Heat Transport

Oceanic Conveyor System Thermohaline (temperature + salinity effect on water density)

Past Climates Climate and ocean circulation has not always been as we see it today. General conditions of ocean and atmosphere have existed since the last major glaciation event about 12,000 – 10,000 years ago (Younger Dryas)

Global Surface Temperatures Terawatt = W

Atmospheric CO2 Concentrations

CO 2 Emissions From Fossil Fuel Burning 35% higher than before industrial revolution 24 billion tons CO 2 added each year Deforestation adds another 1.6 billion tons Where does it all go in addition to the atmosphere? –Oceans = CO 2 sink –Forests = CO 2 source

Ocean and forests reduce the potential rate in carbon dioxide rise from 3 ppm/y to 1.7 ppm/y

Other Greenhouse Gases and Sources Water vapor Methane Nitrous oxide CFC’s and other halocarbons Hydrological cycle Animal husbandry Chemical fertilizers* Refrigerants* * = Long residence times and contribute to ozone depletion

Evidences of Global Warming Nine out of 14 hottest years Wide-scale recession of glaciers Sea level rising Predicted mean global temperature change by 2100 is between 1.5 and 4.5 C o

Impacts of Global Warming Melting of polar ice caps Flooding of coastal areas Massive migrations of people inland Alteration of rainfall patterns Deserts becoming farmland and farmland becoming deserts Significant losses in crop yields

The El Nino: What Happened? Development of warm water in the eastern pacific over time. Reversal in trade winds that normally blow from an easterly direction. Warm water spread to the east. Global patterns in moisture and evaporation changed.

The El Nino: What Happened? Jet streams shifted from normal course. AprilMay June September

The El Nino Effects

Reducing CO2 Emissions (True or False) Reducing use of fossil fuels Adopt a wait-and-see attitude Develop alternative energy sources Plant trees Examine other possible causes of global warming Make and enforce energy conservation rules Rely on the government Adopt the precautionary principle Raise the minimum driving age to 18 years

Framework Convention on Climate Change (FCCC; 1997) “Kyoto Accord” Reduce emissions to 1990 levels by 2010 For US to achieve this requires a 30% reduction of present use. (Republican congress voted NO.) Globally, by 2010 CO 2 emissions will have increased by 30% due to developing countries. Bottom line: need 60% reduction in CO 2 emission worldwide NOW to stabilize greenhouse gas concentrations at today’s levels.

Ozone Good Ozone! Bad Ozone!

Electromagnetic Spectrum

Affects of UV Light Exposure Skin cancer (700,000 new cases each year) Premature skin aging Eye damage Cataracts Blindness

Formation of the Ozone Shield Reaction #1: UV light + O 2 O + O Reaction #2: Free O + O 2 O3O3 Reaction #3: Free O + O 3 O 2 + O 2 Reaction #4: UV light + O 3 O + O 2

Chlorofluorocarbons (CFC’s) Organic molecules in which both chlorine and fluorine atoms replace some of the hydrogen atoms. Sources: –refrigerators and air conditioners –production of plastic foam –cleaner for electronic parts –pressurizing agent in aerosol cans

Breakdown of Ozone Shield Reaction #5: CFCl 3 + UV Cl + CFCl 2 Reaction #6: Cl + O 3 ClO + O 2 Reaction #7: ClO + ClO 2Cl + O 2 Which reaction releases Cl from CFC’s? Which reaction generates more Cl? Chlorine is a catalyst that destroys the production of ________?

Montreal Protocol scale back CFC production by 50% by amendment to completely phase out ozone destroying chemicals by amendment to completely phase out ozone destroying chemicals by 1996 Why the rush?

The Clean Air Act: Title IV Restricts production, use, emissions and disposal of ozone depleting chemicals. Regulates the servicing of refrigeration and air-conditioning units. “Protecting Stratospheric Ozone”