Chapter 16: Global Climate Change

Lesson 1: Our Dynamic Climate

Energy From the Sun The heating of Earth’s atmosphere by the sun is influenced by the greenhouse effect, latitude, and sunspot cycles. The greenhouse effect is a natural process in which certain gases in the atmosphere keep heat near Earth and prevent it from radiating into space. The gases that do this are called greenhouse gases

Tropospheric ozone (O3) Nitrous oxide (N2O) Methane (CH4) Major greenhouse gases: Water vapor (H2O) Carbon dioxide (CO2) Other greenhouse gases: Tropospheric ozone (O3) Nitrous oxide (N2O) Methane (CH4) Greenhouse gases do not stop sunlight from getting through to the Earth’s surface, but absorb some of the heat that is radiated back from Earth’s surface, and release it slowly.

Latitude is a measurement of a place’s distance from the equator. The relationship between climate and latitude happens because the sun’s radiation strikes regions of Earth at different angles, causing unequal heating. Tropical areas are generally hot because the sun’s rays hit the equator most directly all year round. Polar regions are colder because of the angle at which the rays strike the polar areas spreads the energy out over a larger area. Regions between the poles and the equator are in temperate climate zones The seasons change because, as the Earth orbits the sun, the angle at which the sun’s rays strike parts of the Earth changes.

A sunspot is a dark spot on the surface of the sun. The more sunspots present on the surface of the sun, the more energy the sun gives off. The number of sunspots rises and falls in cycles that last about 11 years.

Wind Patterns in the Atmosphere Winds distribute heat and moisture globally The rising of air in equatorial regions and the sinking of air in polar regions help create global wind patterns. Warm air moves away from the equator and toward the poles, and cold air moves in the opposite direction In general, warm air can carry more water vapor than cooler air can

The Oceans and Climate Oceans affect climate by transporting heat and absorbing carbon dioxide A worldwide system of ocean currents is caused by a combination of unequal heating of water and unequal salinity.

Thermohaline circulation is an ocean pattern in which warm, less salty water moves along the surface of the water, and cooler, saltier water moves deep below the ocean surface Cool water generally has greater density than warm water Saltier water is denser than water with a lower salinity

La Niña is the opposite of El Niño El Niño is a change in air pressure, wind patterns, ocean temperature, and ocean circulation in the Pacific Ocean. Equatorial winds weaken Surface water in the eastern Pacific Ocean becomes warmer than normal Causes rainstorms and floods in usually dry areas La Niña is the opposite of El Niño Temperature in the eastern Pacific Ocean are colder than average

The absorption of carbon dioxide by the ocean has a cooling effect on the atmosphere. The oceans absorb carbon dioxide more slowly than it is being added to the atmosphere.

Other Factors that Affect Climate Global climate may be affected by factors such as topography, volcanic eruptions, regional vegetation, and changes in Earth’s orbit. A region’s topography describes the surface characteristics of the area, including its elevation and features such as mountains, rivers, and lakes. In general, the greater the altitude, or elevation, the cooler the air temperature will be

The windward side of the mountain receives precipitation As winds pass over mountains, the rising air cools and clouds often form, and precipitation may fall, but by the time the air has moved to the other side of the mountains it has usually lost much of its moisture. The windward side of the mountain receives precipitation The leeward side of a mountain range (downwind) gets relatively little precipitation

Plants affect the amount of carbon dioxide in the atmosphere If a volcanic eruption is large enough, the gases and particles expelled may block enough sunlight to temporarily cool the atmosphere Vegetation can influence a climate when it covers a large area Plants affect the amount of carbon dioxide in the atmosphere Huge forests can take in an especially large amount of carbon dioxide, and the loss of trees results in carbon dioxide remaining in the atmosphere

One cause of climate changes in history is the periodic variation in Earth’s movement and position in space in relation to the sun. Minor changes in Earth’s orbit, and in the tilt of Earth’s axis, occur in regular cycles

Lesson 2: Climate Change

Evidence of a Warming Earth Evidence of global climate change includes rising atmospheric temperature, precipitation trends, melting ice, and rising seas. Global climate change refers to many climate characteristics, such as temperature, rainfall, wind patterns, and storm frequency. Global warming refers specifically to an increase in Earth’s average surface temperature and is only one aspect of global climate change

The Intergovernmental Panel on Climate Change (IPCC) was established in 1988 by the UN and the World Meteorological Association and is composed of scientists and government officials from around the world. Concluded that global warming is happening and human activities have contributed

Changes in Precipitation Rising Temperatures Between 1906 and 2005 the average atmospheric temperatures near Earth’s surface increased by 0.74C Changes in Precipitation Some regions of the world are receiving more precipitation while other regions are receiving less precipitation Heavy rainstorms have increased in both dry and moist regions around the world resulting in some flooding.

Melting Ice Rising Sea Levels Throughout the world, most glaciers are shrinking or even disappearing Portions of the ice shelf have broken away and melted Rising Sea Levels The primary cause of rising sea levels according to the IPCC is global warming When seawater becomes warmer, its volume increases Water from melting ice also contributes

Studying Climate Change Scientists study changes in climate by taking direct measurements, inferring past climate characteristics, and using models to predict the future. Over time, records of data such as air temperature, precipitation, wind patterns, and ocean temperature show that modern climate is changing.

Proxy indicators are types of indirect evidence that serves as proxies, or substitutes, for direct measurement. Scientists remove long columns, or cores, of ice and analyze the trapped air bubbles to determine such things as greenhouse gas concentrations and temperature trends.

Researchers take samples from beds of sediment beneath bodies of water to study preserved pollen grains and other preserved plant parts. Tree rings in old trees can reveal how much a tree grew in a particular growing season

Climate models are programs that combine what is known about the atmosphere and oceans to simulate, or imitate, climate processes. Use enormous amounts of data and complex mathematical equations Researchers use past climate data to test climate models, comparing the results with what actually happened in the past.

Finding the Cause of Climate Change Evidence indicates that global warming has been caused largely by the increase in greenhouse gases in the atmosphere. In 1958, a scientist named Charles Keeling started to measure carbon dioxide in the atmosphere, taking samples every hour. The carefully recorded data of Keeling and his associates show that carbon dioxide concentration in the atmosphere is increasing.

Land-use changes have also caused an increase in greenhouse gases The concentration carbon dioxide, nitrous oxide, and methane have all increased, all of which are greenhouse gases. The main source of extra carbon dioxide in the atmosphere is the burning of carbon-containing fuels: fossil fuels. Land-use changes have also caused an increase in greenhouse gases Ex: deforestation

Lesson 3: Effects of Climate Change

Effects on Ecosystems and Organisms As the atmosphere warms, ecosystems on land and in the ocean are changing, affecting organisms in various ways. As the ecosystems on land become warmer, the habitats of some plants and animals have shifted to places where the climate is cooler

Many species of birds are now starting their spring migration earlier than before As sea ice melts earlier and freezes later, it has become more difficult for polar bears to hunt the seals they feed on. In 2008 the polar bear was listed as a threatened species under the Endangered Species Act.

Effects of a Changing Ocean The ocean is becoming warmer and its chemistry is changing because it is absorbing more and more carbon dioxide. Global climate change is one probable reason that coral reefs are dying worldwide, and this loss will affect both ocean biodiversity and the lives of people.

Scientific evidence indicates that coral bleaching is often related to unusually warm water temperatures. Coral bleaching is the death or expulsion of the algae that live in coral reefs and give the coral its bright color Bleached Healthy

The pH of the ocean is slowly decreasing When carbon dioxide dissolves in the water, it forms carbonic acid (H2CO3) The pH of the ocean is slowly decreasing Ocean acidity limits the ability of corals and other shell-building organisms to build their hard, protective coverings.

The future effects of climate change on ecosystems will be complex and are hard to predict. Vegetation may increase Drought and forest fires may increase Some species may become extinct

Impact on People Right Now Global climate change is affecting aspects of human life such as farming, forestry, the economy, and health. Some crops, such as melons and sweet potatoes, do well in heat and have probably benefited from longer growing seasons. Other crops, such as spinach and broccoli, are more suited to cooler conditions.

Forest fires and droughts effect agriculture and forestry Economic effects include decrease in agriculture and forestry yields and storm damage costs. Extreme heat can cause illnesses such as heat exhaustion and heat stroke.

Future Impact on People Computer modeling predicts that global climate change will continue to affect people. The ranges of animals that transmit diseases may expand as parts of the world become warmer. Ex: Lyme disease

As the oceans become warmer and polar ice keeps melting, sea level will continue to rise Many people may need to move Saltwater may intrude into freshwater aquifers Glacier water that usually feeds rivers and reservoirs would eventually decrease and disappear.

Lesson 4: Responding to Climate Change

Use and Production of Electricity Ways of reducing production of greenhouse gases include conserving electricity and finding new ways to produce electricity. 2 basic responses = adaptation and mitigation Adaption involves protecting people from the effects of global warming Mitigation consists of reducing greenhouse gas emissions

A carbon footprint is the amount of carbon dioxide emissions for which an individual or group is responsible Electricity generation is the largest source of US greenhouse gas emissions.

Efficiency and Conservation High-efficiency light bulbs and appliances provide more effective ways to use electricity Energy Star Program offered by the EPA Turn off lights, computers, and televisions when not in use Wash only full loads in dishwashers and clothes washers Unplug cell phone chargers once phone is charged Don’t keep the refrigerator door open

Alternate Sources of Electricity Nuclear power comes from reactions that take place within atoms Solar power uses energy from the sun Wind power depends on wind to make electricity Hydroelectric power uses the movement of water Geothermal power makes use of heat trapped underground

Transportation By choosing more efficient cars, driving less, and using public transportation, people can reduce greenhouse gas emissions. Transportation is the second largest source of US greenhouse gas emissions.

There are now alternatives to cars that burn only gasoline The technology exists to make cars and trucks more fuel-efficient than they are now There are now alternatives to cars that burn only gasoline Hybrid vehicles combine electric motors and gasoline powered engines Driving less and using public transportation save energy, reduce gasoline use, and reduce pollution.

Other Approaches to Reducing Greenhouse Gases Greenhouse gas emission can also be reduced through improved agriculture and forestry, cap-and-trade policies, carbon taxes, carbon offsets, and carbon sequestration.

Agriculture and Forestry Soils and forests absorb carbon dioxide Careful farming practices help preserve soil’s ability to hold carbon. New trees planted to replace those that have been cut down take in carbon dioxide and help prevent soil erosion.

Cap-and-Trade A government puts a limit on the amount of greenhouse gases that can be released by specific industries and power plants Industries that release less greenhouse gas than they are allowed can sell their leftover allowances to industries that are less efficient

Carbon Tax A carbon tax is a fee that a government charges polluters for each unit of greenhouse gases they emit Several European nations have established carbon taxes Most polluters simply pass the cost along to consumers by charging high prices for the goods and services they sell

Carbon Offsets A carbon offset is a voluntary payment made when on industry or person, instead of reducing its own greenhouse gas emissions, pays another group or person to do so. Often difficult to establish effective systems of exchange

Carbon Sequestration Ex: underground storage Scientists are investigating ways to remove carbon dioxide from power plant emissions Carbon sequestration, or storage, consists of ways of storing this captured carbon Ex: underground storage

Cooperation Among Nations The Kyoto Protocol is an agreement among many nations to reduce greenhouse gas emissions. In 1992, many nations signed the United Nations Framework Convention on Climate Change (UNFCCC) – a voluntary plan for reducing greenhouse gas emissions.

The Kyoto Protocol is an international agreement that seeks to limit greenhouse gas emissions. Nations that signed the treaty committed to reducing emissions of greenhouse gases to levels below those of 1990 – binding agreement. Took effect in 2005 after Russia became the 127th nation to ratify it The United States did not sign Requires developed nations to reduce emissions but does not require the same of developing nations

In December 2009, delegates from 192 nations met in Denmark to try to develop an international agreement to address climate change and resulted in the Copenhagen Accord. Developed nations offered to pay billions of dollars to developing nations to help fund mitigation and adaptation strategies, and agreed to set specific targets for emission reduction by 2020. A nonbinding agreement