Chapter 21 Global Climate Change

Overview of Chapter 21 Introduction to Climate Change Causes of Global Climate Change Effects of Climate Change Melting Ice and Rising Sea Level Changes in Precipitation Patterns Effects on Organisms Effects on Human Health Effects on Agriculture Dealing with Global Climate Change

Introduction to Climate Change- Mean Annual Global Temperature 1960-2005

Climate Change Terminology Greenhouse Gas Gas that absorbs infrared radiation Ex: Carbon dioxide, methane, nitrous oxide, chlorofluorocarbons and tropospheric ozone Positive Feedback Change in some condition triggers a response that intensifies the changed condition Infrared Radiation Radiation that has a wavelength that is longer than that of visible light, but shorter than that of radio waves Greenhouse Effect Increase of heat in a system where energy enters (often as light), is absorbed as heat, and released sometime later

Introduction to Climate Change Evidence for Climate Change 11 of the 12 years between 1995 and 2006 were among the twelve warmest years since the mid-1800s Phenological spring in N. hemisphere now comes 6 days earlier Warming is not due to natural causes (are we sure?) Human produced greenhouse gases are most plausible explanation

Causes of Climate Change Greenhouse gas concentrations increasing

Causes of Climate Change Increased concentration of CO2 (right) Burning fossil fuels in cars, industry and homes Deforestation Burning of forests

Greenhouse Effect

Other Pollutants Cool the Atmosphere Atmospheric Aerosols tend to cool the atmosphere Both human and natural sources Tiny particles that remain in troposphere for weeks or months Contain many chemicals, but often contain sulfur Complicates models of climate change

Climate Models Climate affected by: winds, clouds, ocean currents, and albedo Used to explore past climate events Advanced models can project future warming events Models are only as good as the data and law used to program them They have limitations

Climate Models

Effects of Global Climate Change Ocean as CO2 sink - excess CO2 is starting to harm ocean life

Effects of Global Climate Change- Melting Ice and Rising Sea Levels Sea level rise caused in 2 ways Thermal Expansion Water expands as it warms Melting of land ice Retreat of glacier and thinning of ice at the poles Melting has positive feedback Increased melting decreases ice, which decreases albedo leading to further warming

Melting Ice and Rising Sea Levels 1957 1998

Case-In-Point Impacts in Fragile Areas Eskimo Inuit live traditional life dictated by freezing climate Climate change is altering their existence Wildlife are smaller or displaced Reduced snow cover and shorter river ice seasons Thawing of permafrost (right)

Effects of Global Climate Change- Changing Precipitation Patterns Some areas will get more water, some areas will have greater droughts Ex: Hurricanes will likely get stronger

Effects of Global Climate Change- Effects on Organisms Zooplankton in parts of California Current have decreased by 80% since 1951 Effecting entire food chain Decline in krill around Antarctica Caused decrease in penguin populations Species have shifted their geographic range Migrating birds are returning to summer homes earlier Food is not available at this time

Effects on Organisms - Coral Reefs Coral reefs can be bleached (right) due to increase in water temperature Affects coral symbiotes and makes them more susceptible to diseases to which they would otherwise be immune

Effect on Organisms - Vegetation Beech Tree Range

Effects on Human Health Increased number of heat-related illnesses and deaths

Effects on Agriculture Difficult to anticipate Productivity will increase in some areas and decrease in others Rise in sea level will inundate flood plains and river valleys (lush farmland) Effect on pests is unknown Warmer temperatures will decrease soil moisture- requiring more irrigation Location (i.e. elevation and altitude) where certain crops can be grown may have to change

International Implications of Climate Change Developed vs. Developing countries Differing self-interests Differing ability to meet the challenges of climate change

Dealing with Global Climate Change To avoid the worst of climate change, CO2 levels must be stabilized at 550ppm 50% higher than current levels Two ways to attempt to manage climate change Mitigation Focuses on limiting greenhouse gas emissions to moderate global climate change Adaptation Focuses on learning to live with to the environmental changes and societal consequences brought about by global climate change

Dealing with Global Climate Change- Relationship Between Mitigation and Adaptation

Dealing with Global Climate Change- Mitigation Locate/invent alternative fuels to fossil fuels Increase efficiency of cars and trucks Sequestering carbon before it is emitted Plant and maintain trees to naturally sequester carbon

Dealing with Global Climate Change- Adaptation Rising sea levels and coastal populations Move inland Construct dikes and levees Adapt to shifting agricultural zones NYC sewer line

International Efforts to Reduce Greenhouse Gas Emission Kyoto Protocol Legally binding Provides operational rules on reducing greenhouse gases US and Australia have not signed it- it will be difficult to implement without US backing