Chapter 21 Global Climate Change

Climate Change Terminology  Greenhouse Gas  Gas that absorbs infrared radiation  Positive Feedback  Change in some condition triggers a response that intensifies the changed condition  Infrared  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

Greenhouse Effect

Introduction to Climate Change  Evidence for Climate Change  14 warmest years since mid-1800s have occurred since 1990  Phenological spring in N. hemisphere now begins 6 days earlier  Wide-scale recession of glaciers  Sea level rising  Warming is not due to natural causes  Human produced greenhouse gases are most plausible explanation

Russia North pole Greenland Canada Alaska (U.S.) *

PAST CLIMATES  Over the past 900,000 years, the troposphere has experienced prolonged periods of global cooling and global warming.  For the past 1,000 years, temperatures have remained fairly stable but began to rise during the last century.

How Do We Know What Temperatures Were in the Past?  Scientists analyze tiny air bubbles trapped in ice cores learn about past:  troposphere composition.  temperature trends.  greenhouse gas concentrations.  solar, snowfall, and forest fire activity.

 In 2005, an ice core showed that CO 2 levels in the troposphere are the highest they have been in 650,000 years.

Introduction to Climate Change: Mean Annual Global Temperature 1960–2007

Major Greenhouse Gases  Water vapor  Carbon dioxide  Methane  Nitrous oxide.  These gases have always been present in the earth’s troposphere in varying concentrations.

Causes of Climate Change  Increased concentration of CO 2 (right)  Burning fossil fuels in cars, industry and homes  Deforestation  Burning of forests

Global Surface Temperatures

 Measured and projected changes in the average temperature of the atmosphere.

Effects of Global Climate Change  Wildfire in California

Effects of Global Climate Change: Melting Ice and Rising Sea Levels  Sea level rise caused in 2 ways  Thermal Expansion  Melting of land ice  Melting has positive feedback  Increased melting decreases ice, which decreases albedo leading to further warming

Glacier National Park Melting Ice and Rising Sea Levels

 During this century rising seas levels are projected to flood low-lying urban areas, coastal estuaries, wetlands, coral reefs, and barrier islands and beaches.

 Changes in average sea level over the past 250,000 years based on data from ocean cores.

 If seas levels rise by 75cm during this century, most of the Maldives islands and their coral reefs will be flooded.

Effects of Global Climate Change: Changing Precipitation Patterns  Some areas will get more water, some areas will have greater droughts

Changing Ocean Currents  Global warming could alter ocean currents and cause both excessive warming and severe cooling.

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  Species have shifted their geographic range  Migrating birds are returning to summer homes earlier

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

Effect on Organisms: Vegetation

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  More areas may become hospitable to disease vectors  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

Dealing with Global Climate Change  Two ways to manage climate change  Mitigation: Limiting greenhouse gas emissions to moderate global climate change  Adaptation: Learning to live with environmental changes and societal consequences brought about by global climate change

WHAT IS BEING DONE?  Getting countries to agree on reducing their greenhouse emissions is difficult.  A 2006 poll showed that 83% of Americans want more leadership from federal government on dealing with global warming.  President Obama has taken a major stand concerning the reduction of greenhouse gases  He is supporting a new Green Campaign that targets financial incentives for alternative energy and energy efficiency

Cut fossil fuel use (especially coal) Shift from coal to natural gas Improve energy efficiency Shift to renewable energy resources Transfer energy efficiency and renewable energy technologies to developing countries Reduce deforestation Use more sustainable agriculture and forestry Limit urban sprawl Reduce poverty Slow population growth Remove CO 2 from smoke stack and vehicle emissions Store (sequester) CO2 by planting trees Sequester CO 2 deep underground Sequester CO 2 in soil by using no-till cultivation and taking cropland out of production Sequester CO 2 in the deep ocean Repair leaky natural gas pipelines and facilities Use animal feeds that reduce CH 4 emissions by belching cows Solutions Global Warming PreventionCleanup

Reducing CO 2 Emissions Drive a fuel-efficient car, walk, bike, carpool, and use mass transit Use energy-efficient windows Use energy-efficient appliances and lights Heavily insulate your house and seal all drafts Reduce garbage by recycling and reuse Insulate your hot water heater Use compact fluorescent bulbs Plant trees to shade your house during summer Set water heater no higher than 49°C (120°F) Wash laundry in warm or cold water Use low-flow shower head Buy products from companies that are trying to reduce their impact on climate Demand that the government make climate change an urgent priority What Can You Do?