19.1 How Might the Earth’s Temperature and Climate Change in the Future?

Global Warming and Global Cooling Are Not New

• Over the past 4.7 billion years: Volcanic emissions, changes in solar input, movement of the continents, impacts by meteors

• Over the past 900,000 years: Glacial and interglacial periods

• Over the past 10,000 years: Interglacial period

• Over the past 1,000 years: Temperature has been stable

• Over the past 100 years: Temperature changes; methods of determination

Human Activities Emit Large Quantities of Greenhouses Gases

• Since the Industrial Revolution

  • CO2, CH4, and N2O emissions higher

  • Primary sources: agriculture, deforestation, and burning of fossil fuels

• Correlation of rising CO2 and CH4 with increasing global temperatures

• Countries with the most significant CO2 emissions

• Per capita emissions of CO2

• Scientific and economic studies

  • 2007: Field and Marland

    • Tipping point

  • 2008: Aufhammer and Carson

    • China’s CO2 emission growth may be underestimated

• Ice core analysis of air pollutants

The Atmosphere Is Warming Mostly Because of Human Activities

• Intergovernmental Panel on Climate Change (IPCC)

  • 90–99% likely that the lower atmosphere is warming

  • 1906–2005→ Ave. temp increased by about 0.74˚C

  • 1970–2005→ Annual greenhouse emissions up 70%

  • Past 50 years→ the Arctic temp rising almost twice as fast as the rest of the earth

  • Melting of glaciers and floating sea ice

  • Prolonged droughts→ Increasing

• Last 100 years→ sea levels rose 10–20 cm

• What natural and human-influenced factors could have an effect on temperature changes?

  • Amplify

  • Dampen

What Is the Scientific Consensus about Future Temperature Change?

• Weather is short-term changes

  • Temperature, air pressure, precipitation, wind

• The climate is the average conditions in a particular area over a long period of time

  • Temperature and precipitation

  • Fluctuations are normal

• Mathematical models used for predictions

• Global change: changes in the biological, physical, and chemical properties of Earth

• Global climate change: changes in average climate (long-term weather patterns over years or decades)

• Global warming: rapid rate of increasing temperatures

• Human factors are the major cause of temperature rise since 1950

• Human factors will become a greater risk factor

• Monsoons: Climatic systems anywhere in which the moisture increases dramatically in the warm season

• Jet Stream: Current of fast-moving air found in the upper levels of the atmosphere

Is a Hotter Sun the Culprit? Can the Oceans Save Us?

• Since 1975

  • Troposphere has warmed

  • Stratosphere has cooled

• This is not what a hotter sun would do

• Solubility of CO2 in ocean water

• Warmer oceans

  • CO2 levels increasing acidity

  • Effect on atmospheric levels of CO2

  • Effect on coral reefs

• Antarctica’s Southern Ocean and the North Atlantic Ocean

  • Decrease in CO2 uptake

  • Significance on global CO2 levels

Effects of Cloud Cover on Global Warming

• Greenhouse gases absorb heat radiated by the earth

  • The gases then emit infrared radiation that warms the atmosphere

• Without the natural greenhouse effect

  • We would have a cold, uninhabitable earth

• Warmer temperatures create more clouds

  • Thick, light-colored low-altitude clouds: decrease surface temperature

  • Thin, cirrus clouds at high altitudes: increase surface temperature

• Effect of jet entrails on climate temperature

Outdoor Air Pollution Can Temporarily Slow Global Warming

• Aerosol and soot pollutants

  • Will not enhance or counteract projected global warming

  • Fall back to the earth or are washed out of the lower atmosphere

19.2 What Are Some Possible Effects of a Warmer Atmosphere?

Enhanced Global Warming Could Have Severe Consequences

• The tipping point and irreversible climate change

• Worst-case scenarios

  • Ecosystems collapsing

  • Low-lying cities flooded

  • Wildfires in forests

  • Prolonged droughts: grasslands become dustbowls

  • More destructive storms

  • Glaciers shrinking; rivers drying up

Projected Effects of Global Warming and the Resulting Changes in Global Climate

• 2°C Warming with 450 ppm CO2: Forest fires worsen, prolonged droughts intensify, and deserts spread

• 3°C Warming with 550 ppm CO2: Forest fires get much worse, prolonged droughts get much worse, deserts spread more, and irrigation and hydropower decline

• 4°C Warming with 650 ppm CO2: Forest fires and drought increase sharply, water shortages affect almost all people, crop yields fall sharply in all regions and cease in some regions

Severe Drought Is Increasing: The Browning of the Earth

• Accelerate global warming, lead to more drought

• Biodiversity will decrease

• NPP will decrease

• Dry climate ecosystems will increase

• Other effects of prolonged lack of water

Ice and Snow Are Melting

• Mountain glaciers affected by

  • Average snowfall

  • Average warm temperatures

• Europe’s Alps: Glaciers are disappearing

• South America: Glaciers are disappearing

• Greenland: Warmer temperatures

Science Focus: Melting Ice in Greenland

• Largest island: 80% composed of glaciers

• 10% of the world’s freshwater

• 1996–2007: net loss of ice doubled

• Effect on sea level if melting continues

Sea Levels Are Rising

• Projected irreversible effect

  • Degradation and loss of 1/3 of coastal estuaries, wetlands, and coral reefs

  • Disruption of coastal fisheries

  • Flooding of

    • Low-lying barrier islands and coastal areas

    • Agricultural lowlands and deltas

  • Contamination of freshwater aquifers

  • Submergence of low-lying islands in the Pacific and Indian Oceans and the Caribbean

Permafrost is Likely to Melt

• Carbon present as CH4 in permafrost soils and lake bottoms

• 2004: Arctic Climate Impact Assessment

  • 10–20% of the permafrost might melt this century

• Effect of global warming

Global Warming Is a Major Threat to Biodiversity

• Most susceptible ecosystems

  • Coral reefs

  • Polar seas

  • Coastal wetland

  • High-elevation mountaintops

  • Alpine and arctic tundra

• Organisms that increase global warming

  • Insects, fungi, and microbes

Climate Change

• Regions of farming may shift

  • Decrease in tropical and subtropical areas

  • Increase in northern latitudes

    • Less productivity; soil not as fertile

• Genetically engineered crops more tolerant to drought

• Deaths from heat waves will increase

• Deaths from cold weather will decrease

• Higher temperatures can cause

  • Increased flooding

  • Increase in some forms of air pollution, more O3 More insects, microbes, toxic molds, and fungi

19.3 What Can We Do to Slow Climate Change?

Dealing with Climate Change Is Difficult

• Global problem

• Long-lasting effects

• Long-term political problem

• Harmful and beneficial impacts of climate change unevenly spread

• Many proposed actions disrupt economies and lifestyles

Options

• Drastically reduce the amount of greenhouse gas emissions

• Devise strategies to reduce the harmful effects of global warming

Avoiding Catastrophe: We Can Reduce the Threat of Climate Change

• Input or prevention strategies

• Improve energy efficiency to reduce fossil fuel use

• Stop cutting down tropical forests

• Output Strategy

• Capture and store CO2

• Socolow and Pacala

  • Climate stabilization wedges

  • Keep CO2 emissions to 2007 levels by 2057

• Brown→ need to do more

  • Cut CO2 emissions by 80% by 2020

  • 2008 book: Plan B 3.0; Mobilizing to Save Civilization

• Output solutions

  • Massive global tree planting; how many?

  • Wangari Maathai Great Wall of Trees: China and Africa

• Plant fast-growing perennials on degraded land

• Capturing and storing CO2

Global Warming Solutions

• Prevention

  • Cut fossil fuel use (especially coal)

  • The 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

• Cleanup

  • Remove CO2 from smokestacks and vehicle emissions

  • Store (sequester) CO2 by planting trees

  • Sequester CO2 deep underground (with no leaks allowed)

  • Sequester CO2 in soil by using no-till cultivation and taking cropland out of production

  • Sequester CO2 in the deep ocean (with no leaks allowed)

  • Repair leaky natural gas pipelines and facilities

  • Use animal feeds that reduce CH4 emissions from cows (belching)

The Kyoto Protocol

• Treaty to slow climate change

• Reduce emissions of CO2, CH4, and N2O by 2012 to levels of 1990

• Trading greenhouse gas emissions among countries

• Not signed by U.S. President G.W. Bush

Other countries

• Costa Rica: goal to be carbon neutral by 2030

• Norway: aims to be carbon neutral by 2050

• China and India must change their energy habits

• U.S. cities and states taking initiatives to reduce carbon emissions

Some Companies and Schools Are Reducing Their Carbon Footprints

• Major global companies reducing greenhouse gas emissions

  • Alcoa

  • DuPont

  • IBM

  • Toyota

  • GE

  • Wal-Mart

    • Fluorescent light bulbs

    • Auxiliary power units on truck flee

• Colleges and universities reducing greenhouse gas emissions

  • Oberlin College, Ohio, U.S.

  • 25 Colleges in Pennsylvania, U.S.

  • Yale University, CT, U.S.