Chapter Introduction

Lesson 1 Climates of Earth

Lesson 2 Climate Cycles

Lesson 3 Recent Climate Change

Chapter Wrap-Up

What is climate and how does it impact life on Earth?

What do you think?

Before you begin, decide if you agree or disagree with each of these statements. As you view this presentation, see if you change your mind about any of the statements.

1. Locations at the center of large continents usually have the same climate as locations along the coast.

2. Latitude does not affect climate.

3. Climate on Earth today is the same as it has been in the past.

Do you agree or disagree?

4. Climate change occurs in short-term cycles.

5. Human activities can impact climate.

6. You can help reduce the amount of greenhouse gases released into the atmosphere.

Do you agree or disagree?

• What is climate?

• Why is one climate different from another?

• How are climates classified?

Climates of Earth

• climate

• rain shadow

• specific heat

• microclimate

Climates of Earth

• Climate is the long-term average weather conditions that occur in a particular region.

• A region’s climate depends on average temperature and precipitation, as well as how these variables change throughout the year.

What is climate?

What is climate?

What is climate? (cont.)

The latitude of a location affects climate.

What affects climate?

• The amount of solar energy per unit of Earth’s surface area depends on latitude.

• Earth’s curved surface causes latitudes closer to the equator to receive more direct sunlight than latitudes farther north or south.

What affects climate? (cont.)

Latitudes near the poles receive less solar energy and have lower average temperatures.

What affects climate? (cont.)

Latitudes near the equator tend to have warmer climates than higher latitudes.

What affects climate? (cont.)

• Climate is influenced by altitude.

• Temperature decreases as altitude increases in the troposphere.

Mountains influence climate because they are barriers to prevailing winds.

What affects climate? (cont.)

An area of low rainfall on the downwind slope of a mountain is called a rain shadow.

What affects climate? (cont.)

• The high specific heat of water causes the climates along coastlines to remain somewhat constant.

• Specific heat is the amount of thermal energy needed to raise the temperature of 1 kg of a material by 1°C.

• Prevailing winds extend the moderate temperatures farther inland.

What affects climate? (cont.)

• Ocean currents modify climate.

• The Gulf Stream is a warm, northward current along the east coast of North America.

• The Gulf Stream brings warmer temperatures to portions of the United States and Europe.

What affects climate? (cont.)

Climates are classified into five types based on their temperature, precipitation, and native vegetation.

Classifying Climates

Classifying Climates (cont.)

How are climates classified?

• A city’s roads and buildings absorb solar radiation.

• Cities are often warmer than the surrounding area.

• This urban heat island is one form of microclimate.

Classifying Climates (cont.)

A microclimate is a localized climate that is different from the climate of the larger area surrounding it.

Classifying Climates (cont.)

microclimate

from Greek mikros, means “small”; and klima, means “region, zone”

Classifying Climates (cont.)

Why is one climate different from another?

• Climate influences how humans determine the crops they grow.

• Climate influences how humans design buildings.

How Climate Affects Living Organisms

Animals and plants have adapted to the climates in which they live.

CORBIS

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• Climate is influenced by several factors including latitude, altitude, and an area’s location relative to a large body of water or mountains.

• Rain shadows occur on the downwind slopeof mountains.

• Microclimates can occur in urban areas, forests, and hilltops.

A. around the globe

B. locally

C. in a particular region

D. in the troposphere

Climate is the long-term average weather conditions that occur where?

A. climate

B. the Gulf Stream

C. a microclimate

D. a rain shadow

An area of low rainfall on the downwind slope of a mountain is called what?

A. cooler

B. more constant

C. more erratic

D. warmer

Which of these describes a coastline climate compared to a continental climate?

1. Locations at the center of large continents usually have the same climate as locations along the coast.

2. Latitude does not affect climate.

Do you agree or disagree?

• How has climate varied over time?

• What causes seasons?

• How does the ocean affect climate?

Climate Cycles

• ice age

• interglacial

• El Niño/Southern Oscillation

• monsoon

• drought

Climate Cycles

Much of our knowledge about past climates comes from natural records of climate.

Long-Term Cycles

• ice cores from glaciers and ice sheets

• fossilized pollen

• ocean sediments

• growth rings of trees

Long-Term Cycles (cont.)

• Ice ages are cold periods lasting from hundreds to millions of years when glaciers cover much of Earth.

• Glaciers and ice sheets advance during cold periods and retreat during interglacials—the warm periods that occur during ice ages.

Long-Term Cycles (cont.)

interglacial

from Latin inter–, means “among, between”; and glacialis, means “icy, frozen”

• The most recent ice age began about 2 million years ago.

• At that time, about half the northern hemisphere was covered by ice.

• About 10,000 years ago, Earth entered its current interglacial period, called the Holocene Epoch.

Long-Term Cycles (cont.)

• Earth’s orbit varies between elliptical and circular about every 100,000 years.

• As Earth’s orbit changes shape, Earth’s climates change.

Long-Term Cycles (cont.)

Long-Term Cycles (cont.)

When Earth’s orbit is more circular, Earth averages a greater distance from the Sun, resulting in below-average temperatures on Earth.

• Changes in the angle of Earth’s tilt affect the range of temperatures throughout the year.

• The tilt of Earth’s axis changes in 41,000-year cycles.

Long-Term Cycles (cont.)

Movement of Earth’s continents and changes in ocean circulation influence long-term climate cycles.

Long-Term Cycles (cont.)

Long-Term Cycles (cont.)

How has climate varied over time?

In addition to long-term climate cycles, climate also changes in short-term cycles.

Short-Term Cycles

The changing seasons is an example of short-term climate change.

Short-Term Cycles (cont.)

Changes in the amount of solar energy received at different latitudes during different times of the year give rise the seasons.

When the northern hemisphere is tilted toward the Sun, there are more daylight hours than dark hours, the temperatures are warmer, and it is summer.

When the northern hemisphere is tilted away from the Sun, daylight hours are fewer than nighttime hours, temperatures are colder, and it is winter.

Short-Term Cycles (cont.)

What causes seasons?

The seasons change as Earth makes a revolution around the Sun.

Short-Term Cycles (cont.)

revolutionScience Use the action by a celestial body of going around in an orbit or an elliptical courseCommon Use a sudden, radical, or complete change

In the northern hemisphere, summer begins when the northern hemisphere is tilted toward the Sun.

In the northern hemisphere, fall begins when the neither hemisphere is tilted toward the Sun.

In the northern hemisphere, winter begins when the northern hemisphere is tilted away from the Sun.

In the northern hemisphere, spring begins when, once again, neither hemisphere is tilted toward the Sun.

The El Niño/Southern Oscillation (ENSO) causes another type of short-term climate change.

During ENSO, the trade winds weaken and warm water surges back toward South America.

A complete ENSO cycle occurs every three to eight years, with the following effects:

• lots of precipitation along the western coast of South America

• droughts in normally wet regions

• increased number of violent storms in California and southern U.S.

Short-Term Cycles (cont.)

• The North Atlantic Oscillation (NAO) is another cycle that can change the climate for decades at a time.

• The NAO affects the strengths of storms throughout North America and Europe by changing the position of the jet stream.

Short-Term Cycles (cont.)

• A third short-term climate change is a monsoon.

• A monsoon is a seasonal change in wind direction caused by changing temperatures over the ocean and land.

Short-Term Cycles (cont.)

Short-Term Cycles (cont.)

How does the ocean affect climate?

• A drought is a period with below-average precipitation that can lead to crop damage and water shortages.

• Droughts are often accompanied by heat waves—periods of unusually high temperatures.

Other Short-term Climate Changes

• Droughts and heat waves occur when large hot-air masses remain in one place for weeks or months.

• A cold wave occurs when a large polar air mass stays over a region for days or weeks.

Other Short-term Climate Changes(cont.)

• Scientists learn about past climates by studying natural records of climate, such as ice cores, fossilized pollen, and growth rings of trees.

• Long-term climate changes, such as ice ages and interglacials, can be caused by changes in the shape of Earth’s orbit and the tilt of its axis.

• Short-term climate changes include seasons, El Niño/Southern Oscillation, and monsoons.

A. glacial periods

B. ice ages

C. interglacials

D. winter

Glaciers and ice sheets retreat during which of these?

A. 10 years

B. 400 years

C. 41,000 years

D. 4,000,000 years

The tilt of Earth’s axis changes in cycles that last how long?

A. solstices

B. seasons

C. equinoxes

D. atmospheric cycles

Which marks the beginnings of winter and summer?

3. Climate on Earth today is the same as it has been in the past.

4. Climate change occurs in short-term cycles.

Do you agree or disagree?

• How can human activities affect climate?

• How are predictions for future climate change made?

Recent Climate Change

• global warming

• greenhouse gas

• deforestation

• global climate model

Recent Climate Change

Average temperatures on Earth have been increasing for the past 100 years.

Regional and Global Climate Change

Temperature change has not been steady throughout the past 100 years.

Regional and Global Climate Change (cont.)

• The rise in Earth’s average temperature during the past 100 years is often referred to as global warming.

• In 2007, the Intergovernmental Panel on Climate Change (IPCC) concluded that most of this temperature increase, or global warming, is due to human activities.

Human Impact on Climate Change

• These activities include burning fossil fuels and the large-scale cutting and burning of forests, which release greenhouse gases into the atmosphere.

• Gases in the atmosphere that absorb Earth’s outgoing infrared radiation are greenhouse gases.

Human Impact on Climate Change (cont.)

Greenhouse gases help keep temperatures on Earth warm enough for living things to survive—a phenomenon called the greenhouse effect.

Human Impact on Climate Change (cont.)

Recently, global temperatures and carbon dioxide, CO2, concentration in the atmosphere have both increased.

Human Impact on Climate Change (cont.)

• Higher levels of greenhouse gases, like CO2, create a greater greenhouse effect.

• Most scientists suggest that global warming is due to the greater greenhouse effect.

• Humans use deforestation to obtain fuel or clear farm land.

Human Impact on Climate Change (cont.)

Deforestation is the large-scale cutting and/or burning of forests.

Human Impact on Climate Change (cont.)

deforestation

from Latin de–, means “down from, concerning”; and forestum silvam, means “the outside woods”

• Deforestation affects global climate because there are fewer living trees to help remove CO2 from the air.

• The burning of cut trees also adds more CO2 to the atmosphere.

• Natural sources of CO2 include volcanic eruptions and forest fires.

• Cellular respiration in organisms contributes additional CO2.

Human Impact on Climate Change (cont.)

• The burning of fossil fuels also releases tiny liquid or solid particles into the atmosphere called aerosols.

• Most aerosols reflect sunlight back into space, preventing some of the Sun’s energy from reaching Earth and potentially cooling the climate over time.

Human Impact on Climate Change (cont.)

When clouds form in areas with large amounts of aerosols, the cloud droplets are smaller and reflect more sunlight than clouds with larger droplets.

Human Impact on Climate Change (cont.)

How can human activities affect climate?

Human Impact on Climate Change (cont.)

• Increasing temperatures can impact the environment in many ways.

• Melting glaciers and polar ice sheets can cause sea levels to rise and coastal ecosystems to be disrupted.

Climate and Society

• Extreme weather events can become more common.

• Permanently higher temperatures and other ecosystem changes can affect migration patterns of insects, birds, fish, and mammals.

Climate and Society (cont.)

• Climate forecasts help governments decide how to respond to future climate changes.

• A global climate model (GCM) is a set of complex equations used to predict future climates.

• GCMs use math and science to predict future climate changes.

Predicting Climate Change

• Summer arctic sea ice is expected to disappear by the end of this century.

• Sea levels are expected to keep rising for several centuries.

Predicting Climate Change (cont.)

Predicting Climate Change (cont.)

How are predictions for future climate change made?

Increasing populations can affect climate change.

Predicting Climate Change (cont.)

• It is predicted that by the year 2030, two of every three people on Earth will live in urban areas.

• Large areas of forests are being cleared for expanding cities.

• Significant amounts of greenhouse gases and other pollutants will be added to the atmosphere.

Predicting Climate Change (cont.)

There are ways to reduce pollution and greenhouse gases.

Predicting Climate Change (cont.)

• developing alternative energy sources, such as solar and wind energy

• building energy-efficient buildings

• controlling greenhouse gases and pollution by conserving fuel and recycling

• Many scientists suggest that global warming is due to increased levels of greenhouse gases in the atmosphere.

• Human activities such as deforestation and burning fossil fuels, can contribute to global warming.

• Ways to reduce greenhouse gas emissions include using solar and wind energy and creating energy-efficient buildings.

A. aerosols

B. carbon dioxide

C. greenhouse gases

D. vapor

The burning of fossil fuels releases tiny liquid or solid particles into the atmosphere called what?

A. global climate model

B. meteorological measurement

C. supercomputer

D. weather report

What term refers to the set of complex equations used to predict future climates?

A. oxygen

B. GCMs

C. fossil fuels

D. carbon dioxide

Deforestation can lead to more of which of these in the atmosphere?

5. Human activities can impact climate.

6. You can help reduce the amount of greenhouse gases released into the atmosphere.

Do you agree or disagree?

Key Concept Summary

Interactive Concept Map

Chapter Review

Standardized Test Practice

Climate is the long-term average weather conditions that occur in an area. It is influenced by the interactions between Earth’s systems. Living things have adaptations to the climate in which they live.

• Climate is the long-term average weather conditions that occur in a particular region.

• Climate is affected by factors such as latitude, altitude, rain shadows on the downwind slope of mountains, vegetation, and the specific heat of water.

• Climate is classified based on precipitation, temperature, and native vegetation.

Lesson 1: Climates of Earth

Lesson 2: Climate Cycles

• Over the past 4.6 billion years, climate on Earth has varied between ice ages and warm periods. Interglacials marked warm periods on Earth during ice ages.

• Earth’s axis is tilted. This causes seasons as Earth revolves around the Sun.

• The El Niño/Southern Oscillation and monsoons are two climate patterns that result from interactions between oceans and the atmosphere.

• Releasing carbon dioxide and aerosols into the atmosphere through burning fossil fuels and deforestation are two ways humans can affect climate change.

• Predictions about future climate change are made using computers and general circulation models.

Lesson 3: Recent Climate Change

A. weather system

B. rain shadow

C. microclimate

D. Gulf stream

What term describes a localized climate that is different from the climate of the larger area surrounding it?

A. changes

B. decreases

C. increases

D. stabilizes

In the troposphere, temperature decreases as altitude does what?

A. fall equinox

B. spring equinox

C. summer solstice

D. winter solstice

Which occurs in the northern hemisphere when it is tilted toward the Sun?

A. aerosols

B. clouds

C. fossil fuels

D. greenhouse gases

Gases in the atmosphere that absorb Earth’s outgoing infrared radiation are called what?

A. weather reports

B. greenhouse effects

C. climate forecasts

D. climate cycles

Which helps governments decide how to respond to future climate changes?

A. weather

B. specific weather

C. rain shadow

D. climate

Which refers to the long-term average weather conditions that occur in a particular region?

A. boiling point

B. climate

C. melting point

D. specific heat

Which refers to the amount of thermal energy needed to raise the temperature of 1 kg of a material by 1°C?

A. drought

B. heat wave

C. jet stream

D. monsoon

A wind circulation pattern that changes direction with the seasons is called what?

Which occurs when a large continental polar air mass stays over a region for days or weeks?

A. cold waves

B. droughts

C. heat waves

D. monsoons

A. greenhouse effect

B. global warming

C. global cooling

D. deforestation

What refers to the rise in Earth’s average surface temperature during the past 100 years?