Volcanoes: Gases and particles can temporarily block sunlight, causing air to cool.
Vegetation: Plant life promotes cloud formation and absorbs carbon dioxide.
Earth’s orbit: Changes in Earth’s orbit and the tilt of Earth’s axis affect the distribution of solar radiation.
Evidence of a Warming Earth
Rising global surface temperatures
Changes in precipitation patterns
Melting ice (glaciers, polar ice)
Rising sea level
Climate Change
Study
Studying Climate Change
Direct measurement is used to study today’s climate.
Proxy indicators, such as patterns in tree rings, give clues about past climates.
Models are used to make predictions about future climates.
Cause
Finding the Cause of Climate Change
According to studies, increases in greenhouse gases are the primary cause of climate change.
The increase in greenhouse gases is mainly due to burning of fossil fuels and changes in land use.
Effects on Organisms
Habitats shift, usually toward the poles or to higher altitudes.
Migrations start earlier in the spring.
Loss of ice makes hunting seals difficult for polar bears.
Effects of Climate Change
Effects on the Oceans
Ocean
An increase in ocean temperature is associated with a process called coral bleaching, in which algae living within corals die. Without the algae, coral cannot survive.
Changes in ocean acidity, resulting from an increase in dissolved carbon dioxide, can harm organisms.
Current Effects of Global Climate Change
Current Effects
Agriculture and forestry: Effects are complex.
Can be positive: Lengthened growing season for some crops
Can be negative: Droughts and forest fires
Economy: Decreased yields; increased property damage due to severe storms and climate conditions
Human health: Extreme heat waves increasingly common, can cause heat stroke and death
Future Effects of Climate Change
Future Effects
Diseases: Warmer temperatures can promote spread of diseases transmitted from animals to people.
Sea level: Low-lying populated coastal areas may flood as sea levels rise.
Water supply: Saltwater contamination of aquifers resulting from rising sea levels and a decrease in glacial ice may threaten freshwater supplies.
Use and Production of Electricity
Carbon footprint: The amount of carbon dioxide for which an individual or group is responsible
Most electricity is generated by burning fossil fuels.
Reducing electricity use reduces carbon footprints.
Ways to reduce electricity use:
Use energy-efficient technologies, which lessen the electricity needed to do a job.
Reduce the use of electrical devices and appliances.
Responding to Climate Change
Alternate Sources of Energy
Alternative Sources of Electricity
Nuclear power
Solar power
Wind power
Hydroelectric power
Geothermal power
Alternates
Advances in Vehicle Technology
Transportation is the second largest source of greenhouse gas emissions in the United States, second only to electricity.
Alternatives to fuel-only cars include:
Gasoline-electric hybrid vehicles
Vehicles that use alternative fuels such as compressed natural gas
Vehicles that use hydrogen fuel cells.
Advances
Reducing Dependence on Cars
Biking, walking, and using public transportation are all ways to reduce fossil fuel use.
Many communities lack good public transportation.
Reducing Dependence
Strategies for Reducing Greenhouse Gases
Agriculture / forestry: Reduce soil erosion and replace cut trees, to curb carbon dioxide emissions
Cap-and-Trade: System of emission allowances that can be sold or traded, gives companies incentive to reduce emissions
Carbon tax: A tax per unit on emissions
Carbon offsets: Instead of directly reducing emissions, companies can make a voluntary payment to a group that reduces or curbs greenhouse gases.
Carbon sequestration: Technology is used to trap and store carbon dioxide emissions.
Strategies
Cooperation Among Nations
Cooperation
The Kyoto Protocol is a binding international effort to reduce greenhouse gases to below 1990 levels.
The United States did not sign the Kyoto Protocol.
Many nations are planning to develop a new binding agreement to address global climate change some time in the future.