Global Warming and Global Warming and Climate ChangeClimate Change

““We are embarked on the most We are embarked on the most colossal ecological experiment of colossal ecological experiment of

all time-doubling the concentration all time-doubling the concentration in the atmosphere of an entire in the atmosphere of an entire

planet of one of its most important planet of one of its most important gases – and we really have no idea gases – and we really have no idea

of what might happen.”of what might happen.”

Paul A. ColinvauxPaul A. Colinvaux

Key PointsKey Points

• How has the earth’s climate changed in How has the earth’s climate changed in the past?the past?

• How may it change in the future?How may it change in the future?• What factors can affect changes in the What factors can affect changes in the

average temperature?average temperature?• What are the possible side effects of a What are the possible side effects of a

warmer earth?warmer earth?• What can we do to slow or adapt to global What can we do to slow or adapt to global

climate change?climate change?

18-1: Past Climate Change and 18-1: Past Climate Change and the Natural Greenhouse Effectthe Natural Greenhouse Effect

• Over the past 900,000 years there have been time periods of cooling and warming

• For the past 10,000 years we have had the good fortune of a stable climate

Average temperature over past 900,000 Average temperature over past 900,000 yearsyears

Thousands of years agoThousands of years ago900900 800800 700700 600600 500500 400400 300300 200200 100100 PresentPresent

Av

era

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su

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ce

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mA

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°C)

pe

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°C)

991010

1111

1212

1313

14141515

1616

1717

Av

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su

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mp

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(°C

)A

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°C) Average temperature over past 130 yearsAverage temperature over past 130 years

YearYear18601860 18801880 19001900 19201920 19401940 19601960 19801980 20002000 20202020

13.613.6

13.813.8

14.014.0

14.214.2

14.414.4

14.614.6

14.814.8

15.015.0

What is the Greenhouse EffectWhat is the Greenhouse EffectFor the earth to maintain a For the earth to maintain a

constant temperature constant temperature incoming solar energy incoming solar energy must be balanced by an must be balanced by an equal amount of equal amount of outgoing energyoutgoing energy

Greenhouse EffectGreenhouse Effect::

gases warm the lower gases warm the lower atmosphere by absorbing atmosphere by absorbing some of the infrared some of the infrared radiation radiated from radiation radiated from the earths surface.the earths surface.

The Natural Greenhouse EffectThe Natural Greenhouse Effect

Rays of sunlight penetrate the lower atmosphere and warm the earth's surface.

The earth's surface absorbs much of the incoming solar radiation and degrades it to longer-wavelength infrared radiation (heat), which rises into the lower atmosphere. Some of this heat escapes into space and some is absorbed by molecules of greenhouse gases and emitted as infrared radiation, which warms the lower atmosphere.

As concentrations of greenhouse gases rise, their molecules absorb and emit more infrared radiation, which adds more heat to the lower atmosphere.

(a)(a) (b)(b) (c)(c)

Fig. 6.13, p. 128

Not a Real Not a Real GreenhouseGreenhouse

• In a real greenhouse the air heats up because it can’t escape by convection to outside air

• In reality heat is released and spread through the atmosphere by convection

Actual effect: Tropospheric heating effect

The Role of the Greenhouse Effect The Role of the Greenhouse Effect (GHE)(GHE)

• Discovered in 1896Discovered in 1896

• With no GHE the earth would be too coldWith no GHE the earth would be too cold

• If the GHE acted by itself the average If the GHE acted by itself the average surface temperature would be surface temperature would be 130130oo F F

• Natural cooling takes place by:Natural cooling takes place by:– Releasing heat through evaporationReleasing heat through evaporation

– Water vapor molecules rise to the clouds Water vapor molecules rise to the clouds and release heat into the upper atmosphereand release heat into the upper atmosphere

• Actual average temperature: Actual average temperature: 5959o o FF

Primary Greenhouse GasesPrimary Greenhouse Gases1. Water Vapor: Controlled

by the hydrologic cycle2. Carbon Dioxide: Controlled

by the carbon cycleEvaluation of ancient glacial ice reveals:

• Water vapor levels have been relatively constant over the past 160,000 years

• Carbon dioxide levels have fluctuated

• Fluctuations in global carbon dioxide levels correspond with the fluctuation of the global temperature YearYear

18601860 18801880 19001900 19201920 19401940 19601960 19801980 2000200020102010

-0.2-0.2

0.00.0

0.20.2

0.40.4

0.60.6

0.80.8

1.01.0

1.21.2Observed

Model of greenhouse gases + aerosols + solar output

Tem

per

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(°C

) fr

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198

0–9

9 m

ean

Tem

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(°C

) fr

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198

0–9

9 m

ean

Climate Change and Human Activities

Since the Industrial Since the Industrial Revolution (1750) there Revolution (1750) there has been a sharp rise in:has been a sharp rise in:

1.1. Use of fossil fuelsUse of fossil fuels

2.2. Deforestation and burning Deforestation and burning grasslands to raise cropsgrasslands to raise crops

3.3. Cultivating rice and using Cultivating rice and using fertilizer that releases Nfertilizer that releases N22OO

Largest Contributors to COLargest Contributors to CO2 2

EmissionsEmissions1.1. Thousands of Coal Thousands of Coal

Burning power and Burning power and industrial plantsindustrial plants

2.2. 700 million gasoline 700 million gasoline burning motor vehicles burning motor vehicles (555 million of them are (555 million of them are cars)cars)

Emissions from US factories Emissions from US factories and power plants and power plants produce more COproduce more CO22 than than the combination of 146 the combination of 146 nations (75% of the world nations (75% of the world population)population)

The role of additional CO2 in the Atmosphere:

Most climate scientists believe that Most climate scientists believe that the increased input of COthe increased input of CO22 will… will…

1.1. Enhance the earth’s natural Enhance the earth’s natural greenhouse effectgreenhouse effect

2.2. Raise the average global Raise the average global temperature of the atmosphere temperature of the atmosphere near the surface of the earthnear the surface of the earth

““GLOBAL WARMINGGLOBAL WARMING””

Are we experiencing Global Warming?

The following facts are based on analysis of ice cores, temperature measurements in hundreds of boreholes into the earths surface and atmospheric temperature measurements

• COCO22 concentrations are at their highest level concentrations are at their highest level in the past 20 million yearsin the past 20 million years

• 75% of human caused CO75% of human caused CO22 emissions are emissions are from the burning of fossil fuelsfrom the burning of fossil fuels

• The 20The 20thth century is the hottest in the past century is the hottest in the past 1000 years1000 years

• Since 1861 the global temperature has risen Since 1861 the global temperature has risen 1.1 – 0.41.1 – 0.4o o FF

• 10 hottest years on record have occurred 10 hottest years on record have occurred since 1990since 1990

Global Warming Graph and Map Information

http://data.giss.nasa.gov/gistemp/

Year

1990 2000 2025 2050 2075 2100

100

150

200

250

Ind

ex

(19

00

= 1

00

)Carbon dioxide

MethaneNitrous oxide

Fig. 18.5, p. 451

Evidence of a Warmer Troposphere

• Melting of land based ice Melting of land based ice caps and floating ice at the caps and floating ice at the poles and Greenlandpoles and Greenland

• Shrinking of glaciersShrinking of glaciers• Average sea level rise of 4-Average sea level rise of 4-

8” over the past 100 years8” over the past 100 years• Northward migration of Northward migration of

some fish, tree and other some fish, tree and other species to find an optimal species to find an optimal temperaturetemperature

• Early spring arrival and late Early spring arrival and late autumn frostsautumn frosts

The Effect of Global Warming The Effect of Global Warming on Glacier National Parkon Glacier National Park

1911

2000

Argentina's Upsala Glacier was Argentina's Upsala Glacier was once the biggest in South once the biggest in South America, but it is now America, but it is now disappearing at a rate of 200 disappearing at a rate of 200 meters per year.meters per year.

The image on the left is from an 1859 etching of the Rhone glacier in Valais, Switzerland, and shows ice filling the valley. In 2001, the glacier had shrunk by some 2.5km, and its 'snout' had shifted about 450 meters higher up.

Rising tides

Some scientists predict that a warmer climate will trigger more violent storms, which will cause increased rates of coastal erosion. This is a section of shoreline at Cape Hatteras in North Carolina in the USA, pictured in 1999 and 2004. The southern United States and Caribbean region were battered by a series of powerful hurricanes last year.

The Intergovernmental Panel on Climate Change (IPCC), a consortium of several thousand independent scientists, predicts that sea levels could rise by between 9 and 88cm in the next century.

This would threaten low-lying islands such as Tuvalu in the Pacific. These images, taken this year, show the effects of a higher than usual tide.

As the climate warms up, mountainous regions may experience lower levels of snowfall. This image shows Mount Hood in Oregon at the same time in late summer in 1985 and 2002.

More pests

Tree-eating wood beetles are likely to benefit from a warmer climate and reproduce in ever-increasing numbers. These images show damage to White Spruce trees in Alaska caused by the pests.

Year

1860 1880 1900 1920 1940 1960 1980 2000 2010

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Observed

Model of greenhouse gases + aerosols + solar output

Tem

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(°C

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0–99

mea

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Fig. 18.7, p. 453

What do the changes in climate What do the changes in climate mean for humans?mean for humans?

1.1. Affects the availability Affects the availability of water resources by of water resources by altering rates of altering rates of evaporation and evaporation and precipitationprecipitation

2.2. Shift areas where Shift areas where crops can be growncrops can be grown

3.3. Change average sea Change average sea levelslevels

4.4. Alter the structure and Alter the structure and location of the world’s location of the world’s biomesbiomes

Year1850 1875 1900 1925 1950 1975 2000 2025 2050 2075 21000

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

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5.5

6.0

Ch

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Fig. 18.8, p. 453

CASE STUDY: Early Warnings CASE STUDY: Early Warnings from the Arcticfrom the Arctic

• The poles are heating faster than the rest of the The poles are heating faster than the rest of the earthearth

• The ice in the Arctic Sea is large enough to The ice in the Arctic Sea is large enough to cover the USA and is sensitive to air cover the USA and is sensitive to air temperaturestemperatures

• Temperatures in the Arctic have increased much Temperatures in the Arctic have increased much faster than the average global temperaturefaster than the average global temperature

• The light color of ice reflects 80% of the The light color of ice reflects 80% of the sunlight, if it melts the ocean will be dark and sunlight, if it melts the ocean will be dark and absorb 80%absorb 80%

What will happen if the Arctic Ice What will happen if the Arctic Ice Melts?Melts?

• Greatly amplify warming of the Arctic Greatly amplify warming of the Arctic regionregion

• Reroute warm ocean currentsReroute warm ocean currents

• Could cause significant cooling in parts of Could cause significant cooling in parts of the northern hemispherethe northern hemisphere

• Especially bad cooling in Europe and Especially bad cooling in Europe and Eastern North AmericaEastern North America

• Tundra soil has warmed up so much that Tundra soil has warmed up so much that it is releasing more COit is releasing more CO22 than it is taking in than it is taking in

Case StudyCase Study: News from : News from Antarctica and GreenlandAntarctica and Greenland

• Antarctica has 70% of the Antarctica has 70% of the worlds fresh water and 90% worlds fresh water and 90% of the reflective iceof the reflective ice

• Since 1947 the temperatures Since 1947 the temperatures have increased 10have increased 10ooF in the F in the winter and 4.5winter and 4.5ooF in the F in the summer.summer.

• Ice the size of Delaware have Ice the size of Delaware have broken offbroken off

• Ice melting off the continent Ice melting off the continent adds to the water volume to adds to the water volume to raise sea levelsraise sea levels

Problems in GreenlandProblems in Greenland• The worlds largest island (3x The worlds largest island (3x

the size of Texas)the size of Texas)• If the glaciers melt as they did If the glaciers melt as they did

110,000-130,000 years ago:110,000-130,000 years ago:1.1. Average sea levels would Average sea levels would

rise 13-20 feetrise 13-20 feet2.2. Massive flooding in the low Massive flooding in the low

lying coastal areas and lying coastal areas and citiescities

3.3. Could shut down the Could shut down the Gulf Gulf StreamStream and and North Atlantic North Atlantic CurrentCurrent which keep Europe which keep Europe warmer than it naturally warmer than it naturally would bewould be

This has nothing to do with global warming!!!

http://images.wikia.com/uncyclopedia/images/8/8b/Cat_toast_swirl.gif

Land

Cell

Clouds

Continent

Ocean

Fig. 18.6, p. 452

Oceans 5%

Bare sand 30–60%

Grass 15–25%

Clouds 50–55%

Snow 80–90%

City 10–15%

Forest 5%

Fig. 18.9, p. 454

Today’s sea level

Years before present Present

250,000 200,000 150,000 100,000 50,000 0

–130

0

–426

0

Hei

gh

t ab

ove

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Hei

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w p

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eet)

Fig. 18.11, p. 456

• Increased deaths from heat and disease

• Disruption of food and water supplies

• Spread of tropical diseases to temperate areas

• Increased respiratory disease

• Increased water pollution from coastal flooding

Human Health

• Rising sea levels• Flooding of low-lying islands

and coastal cities• Flooding of coastal estuaries,

wetlands, and coral reefs• Beach erosion• Disruption of coastal

fisheries• Contamination of coastal

aquifiers with salt water

Sea Level and Coastal Areas

• Changes in forest composition and locations

• Disappearance of some forests

• Increased fires from drying

• Loss of wildlife habitat and species

Forests

• Changes in water supply

• Decreased water quality

• Increased drought

• Increased flooding

Water Resources

• Shifts in food-growing areas

• Changes in crop yields

• Increased irrigation demands

• Increased pests, crop diseases, and weeds in warmer areas

Agriculture

• Extinction of some plant and animal species

• Loss of habitats

• Disruption of aquatic life

Biodiversity

• Prolonged heat waves and droughts

• Increased flooding

• More intense hurricanes, typhoons, tornadoes, and violent storms

Weather Extremes

• Increased deaths

• More environmental refugees

• Increased migration

Human Population

Fig. 18.12, p. 458

Presentrange

Futurerange

Overlap

Fig. 18.13, p. 459

Prevention Cleanup

Cut fossil fueluse (especiallycoal)

Shift from coalto natural gas

Transfer energyefficiency andrenewable energytechnologiesto developingcountries

Improve energyefficiency

Shift torenewableenergy resources

Reducedeforestation

Use sustainableagriculture

Slow populationgrowth

Remove CO2

from smokestackand vehicleemissions

Store (sequesterCO2 by planting

trees)

Sequester CO2

underground

Sequester CO2

in soil

Sequester CO2

in deep ocean

Fig. 18.14, p. 461

N

S

Waste less waterDevelop crops that need less water

Move hazardous material storage tanks away from coast

Prohibit new construction on low-lying coastal areas

Stockpile 1 to 5 year supply of key foods

Expand existing wildlife reserves toward poles

Connect wildlife reserves with corridors

Fig. 18.15, p. 465

Scientific Consensus About Future Scientific Consensus About Future Climate Change and its EffectsClimate Change and its Effects

• “Most of the global warming experienced over the past 50 years is the result of human activity”

• 90-95% chance the average global temperature will rise 2.5-10.4oF over the next 100 yrs.

• The average sea level will rise by 35” by the end of the century

The Role of Ice in The Role of Ice in Global WarmingGlobal Warming

The Ice Albedo The Ice Albedo Feedback SystemFeedback System::

• As the ice melts the water that results absorbs more heat speeding up the warming process.

Oceans Moderate the surface Oceans Moderate the surface temperatures:temperatures:

• Removes 29% of the CO2, but water is less capable of dissolving gas as the temperature increases

• As the temperature increases CO2 will bubble out of the oceans.

• Oceans store heat energy deep in the water and may release it into the atmosphere

• There is a conveyor belt that transfers heat around the world that runs based on differences in water density. Fresh water from melted ice may throw the system off

Antarctica

Cold water melting fromAntarctica's ice cap and

icebergs falls to the ocean floor and surges northward, affecting

worldwide circulation.

Cold water melting fromAntarctica's ice cap and

icebergs falls to the ocean floor and surges northward, affecting

worldwide circulation.

GreenlandGreenland

Fig. 18.10, p. 456

The Role of Air Pollution on The Role of Air Pollution on Climate ChangeClimate Change

1.1. Aerosols actually help reduce global Aerosols actually help reduce global warmingwarming

• At high altitudes aerosols attract water to form clouds that reflect sunlight

2.2. Soot is the second biggest Soot is the second biggest contributor to global warming (15-contributor to global warming (15-30%)30%)

• Produced as a product of burning of coal and diesel fuel

How Rapidly Can the Climate Shift?

If it changes quickly in a few decades we may not have time to…

• Switch food growing regionsSwitch food growing regions• Relocate out of flood zonesRelocate out of flood zones• Build levees and dikesBuild levees and dikes

This may lead to large numbers of This may lead to large numbers of premature deaths, social and economic premature deaths, social and economic chaoschaos

Possible Effects of a Warmer World• Changes in water distribution• Changes in plant and animal biodiversity• Cause the coastlines to move in by 0.8miles

putting 200 million people directly at risk• Contamination of water• Extreme weather patterns• Higher death rates due to higher

temperatures• Increased spread of tropical diseases such

as malaria

In a recent chilling assessment, the World Health Organizationn (WHO) reported that human-induced changes in the Earth's climate now lead to at least 5 million cases of

illness and more than 150,000 deaths every year.