Climate ChangesClimate Changes

Chapter 21, Section 3Chapter 21, Section 3

Natural Processes That Change Natural Processes That Change ClimateClimate

The presence of aerosols (volcanic ash, dust, and sulfur-The presence of aerosols (volcanic ash, dust, and sulfur-based aerosols) in the air increases the amount of solar based aerosols) in the air increases the amount of solar radiation that is reflected back into space, causing radiation that is reflected back into space, causing Earth’s lower atmosphere to coolEarth’s lower atmosphere to cool

Changes in ocean circulation (such as El NiChanges in ocean circulation (such as El Niño) also can ño) also can result in short-term climate fluctuationsresult in short-term climate fluctuations

The formation of sunspots, increased solar activity, The formation of sunspots, increased solar activity, appears to correspond with warm periods in Europe and appears to correspond with warm periods in Europe and North AmericaNorth America

Geographic changes in Earth’s land and water bodies, Geographic changes in Earth’s land and water bodies, caused by plate tectonics, cause changes in climatecaused by plate tectonics, cause changes in climate

Changes in the shape of Earth’s orbit and the tilt of Earth Changes in the shape of Earth’s orbit and the tilt of Earth on its axis are other Earth motions that affect global on its axis are other Earth motions that affect global climateclimate

Volcanic EruptionsVolcanic Eruptions

Ocean CirculationOcean Circulation

Concept CheckConcept Check

Identify four natural processes that can result Identify four natural processes that can result in climate changes.in climate changes.

Volcanic eruptions, changes in global ocean Volcanic eruptions, changes in global ocean circulation, solar activity, and certain Earth circulation, solar activity, and certain Earth motions can cause changes in climate.motions can cause changes in climate.

The Greenhouse EffectThe Greenhouse Effect Greenhouse Effect –Greenhouse Effect – a natural warming of both a natural warming of both

Earth’s lower atmosphere and Earth’s surfaceEarth’s lower atmosphere and Earth’s surface The major gases involved in the greenhouse effect The major gases involved in the greenhouse effect

are water vapor and carbon dioxideare water vapor and carbon dioxide The greenhouse gases are transparent to incoming The greenhouse gases are transparent to incoming

solar radiation, but are good absorbers of Earth’s solar radiation, but are good absorbers of Earth’s radiationradiation

The gases maintain warm temperatures in the lower The gases maintain warm temperatures in the lower atmosphere, making Earth habitable for living thingsatmosphere, making Earth habitable for living things

Studies indicate that human activity over the past Studies indicate that human activity over the past 200 years have strengthened this effect200 years have strengthened this effect

Global WarmingGlobal Warming Global Warming –Global Warming – global temperatures increasing as a global temperatures increasing as a

result of increases in carbon dioxide levels, as well as result of increases in carbon dioxide levels, as well as other greenhouse gasesother greenhouse gases

Scientists base their predictions about global warming on Scientists base their predictions about global warming on computer models of change in Earth’s atmosphere, computer models of change in Earth’s atmosphere, called climate modelscalled climate models

Warmer surface temperatures increase evaporation rates, Warmer surface temperatures increase evaporation rates, increasing the amount of water vapor in the atmosphere, increasing the amount of water vapor in the atmosphere, therefore magnifying the effect of carbon dioxide and therefore magnifying the effect of carbon dioxide and other gasesother gases

Temperature increases will cause sea ice to melt, a big Temperature increases will cause sea ice to melt, a big reflector of solar energy, causing more solar energy to be reflector of solar energy, causing more solar energy to be absorbed at the surfaceabsorbed at the surface

Scientists predict more intense heat waves and droughts Scientists predict more intense heat waves and droughts in some regions and fewer such events in other placesin some regions and fewer such events in other places

Energy Consumption in the U.S.Energy Consumption in the U.S.

Carbon Dioxide ConcentrationsCarbon Dioxide Concentrations

Global Temperature VariationsGlobal Temperature Variations

Concept CheckConcept Check

What are some of the possible effects of global What are some of the possible effects of global warming?warming?

Short-term and long-term changes in Short-term and long-term changes in temperature and precipitation patterns that can temperature and precipitation patterns that can result in both wetter-than-normal periods and result in both wetter-than-normal periods and drier-than-normal periods; a rise in sea level; drier-than-normal periods; a rise in sea level; an increase in shoreline erosionan increase in shoreline erosion

AssignmentAssignment

Read Chapter 21, Section 3 (pg. 600-603)Read Chapter 21, Section 3 (pg. 600-603) Do Chapter 21 Assessment #1-32 (pg. 609-610)Do Chapter 21 Assessment #1-32 (pg. 609-610) Study for the Meteorology Unit Test!!!Study for the Meteorology Unit Test!!! Put together 15 lectures and 9 warm ups (they Put together 15 lectures and 9 warm ups (they

should be on the same page as your lectures!)should be on the same page as your lectures!)