Global Climate Global Climate ChangeChange

History of EarthHistory of Earth’’s Climates Climate

Life appeared ~3.8 billion years agoLife appeared ~3.8 billion years ago Photosynthesis began 3.5-2.5 billion Photosynthesis began 3.5-2.5 billion

years agoyears ago– Produced oxygen and removed carbon Produced oxygen and removed carbon

dioxide and methane (greenhouse dioxide and methane (greenhouse gases)gases)

– Earth went through periods of cooling Earth went through periods of cooling (( ““Snowball EarthSnowball Earth””) and warming) and warming

Average temperature over past 900,000 yearsAverage temperature over past 900,000 years

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

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991010

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14141515

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1717Past Climate Change

Recent trends in global temperatures

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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

Global Atmospheric Concentration of CO2

The Sun’s energy passes through the car ’s windshield.

This energy (heat) is trapped inside the car and cannot pass back through the windshield, causing the inside of the car to warm up.

Example of the Greenhouse Effect

Greenhouse gases are the gases present in the atmosphere which reduce the loss of heat into space and therefore contribute to global temperatures through the greenhouse effect. The term greenhouse gas is applied to, in order of relative abundance: water vapor, carbon dioxide, methane, nitrous oxide, ozone and CFCs.

GLOBAL WARMINGGLOBAL WARMING is the PREDICTION that Earthis the PREDICTION that Earth’’s average surface s average surface temperature will increase by 1temperature will increase by 1ooC-3.5C-3.5ooC by the yearC by the year

2050 due to a build-up of greenhouse gases in the 2050 due to a build-up of greenhouse gases in the atmosphere. atmosphere.

CLIMATE CHANGECLIMATE CHANGE is a broader term that refers to long-term changes in is a broader term that refers to long-term changes in

climate, including average temperature and climate, including average temperature and precipitation.precipitation.

What’s the difference between “global warming” and “climate change”?

How Global Warming WorksHow Global Warming Works

Fossil fuels (coal, oil, natural gas)

Carbon Dioxide (CO2)

Past Temperatures Past Temperatures MeasurementMeasurement

Proxy – a method Proxy – a method that approximates a that approximates a particular particular measurement (e.g., measurement (e.g., temperature)temperature)– Ice coresIce cores– Pollen recordsPollen records– Plant macrofossilsPlant macrofossils– Sr/Ca isotope dataSr/Ca isotope data– Oxygen isotopes from Oxygen isotopes from

speleothem calcite speleothem calcite (stalactites and (stalactites and stalagmites) stalagmites)

• Disruption of food and water supplies

• Spread of tropical diseases

• 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

aquifers with salt water

Sea Level and Coastal Areas

• Disappearance of some forests

• Increased fires from drying

• Loss of wildlife habitat and species

Forests

• Decreased water quality

• Increased drought

• Increased flooding

Water Resources

• 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

• More intense hurricanes, tornadoes, and violent storms

Weather Extremes

• Increased deaths

• More environmental refugees

• Increased migration

Human Population

EffectsEffects

Solutions: Dealing with the Threat Solutions: Dealing with the Threat of Climate Changeof Climate Change

Prevention CleanupCut 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 plantingtrees)

Sequester CO2

underground

Sequester CO2 in soil

Sequester CO2 in deep ocean

Do nothing

Do more research before acting

Act now to reduce the risks from climate change

“When an activity raises threats of harm to human health or the

environment, precautionary measures should be take even if some cause and

effect relationships are not fully established scientifically.”

Wingspread Conference, 1998.

Precautionary PrinciplePrecautionary Principle

• Setting goals (Health indicators)• Taking preventive action in the face

of uncertainty• Shifting the burden of responsibility

to the proponents of an activity (Who benefits?)

• Exploring a wide range of alternatives to possibly harmful actions (Is it necessary?)

• Increasing public participation in decision making (transparency of information & environmental justice)

Central componentsCentral components

In 1992 Earth Summit in Rio de Janeiro 106 developedIn 1992 Earth Summit in Rio de Janeiro 106 developednations committed to reduce greenhouse gases to 1990nations committed to reduce greenhouse gases to 1990levels by the year 2000. This was not a requirement solevels by the year 2000. This was not a requirement somost countries did not achieve this goal.most countries did not achieve this goal.

In 1997 in Kyoto, Japan the Kyoto Treaty was signedIn 1997 in Kyoto, Japan the Kyoto Treaty was signedby 161 nations. Developed countries will cut greenhouseby 161 nations. Developed countries will cut greenhouseemissions. Developing countries are exempt. Emissionsemissions. Developing countries are exempt. Emissionstrading would be allowed. By, 2008 US has not ratifiedtrading would be allowed. By, 2008 US has not ratifiedtreaty because developing countries are exempt and treaty because developing countries are exempt and

coal,coal,oil, steel, chemical and automobile companies opposedoil, steel, chemical and automobile companies opposedtreaty because it would be devastating to the economytreaty because it would be devastating to the economyand workers.and workers.

WhatWhat’’s being done now to s being done now to reduce our emissions?reduce our emissions?

Solar Power Wind Power Fuel-Efficiency

What can you do to help What can you do to help solve the problem?solve the problem?

Simple Things To DoSimple Things To Do

Turn off your computer or the TV Turn off your computer or the TV when youwhen you’’re not using it.re not using it.

Take shorter showers. Heating water uses energy.Take shorter showers. Heating water uses energy.

Keep rooms cool by closing the blinds, shades, orKeep rooms cool by closing the blinds, shades, or curtains. curtains.

Turn off the lights when you leave a room. Turn off the lights when you leave a room.

Use compact fluorescent bulbs.Use compact fluorescent bulbs.

Be Bulb Smart—Use CFLsBe Bulb Smart—Use CFLs

IncandescentCompact

Fluorescent

500 lbs. of

coal

What’s the difference?

•1,430 lbs. CO2 pollution avoided

•$30 saved

Simple Things To DoSimple Things To Do

Dress lightly when itDress lightly when it’’s hot instead of turning s hot instead of turning

upup

the air conditioning. Or use a fan.the air conditioning. Or use a fan.

Dress warmly when itDress warmly when it’’s cold instead of turnings cold instead of turning up the heat.up the heat.

Offer to help your parents keep the air filters on Offer to help your parents keep the air filters on

your AC and furnace clean.your AC and furnace clean.

Walk short distances instead of asking for a Walk short distances instead of asking for a ride in the car.ride in the car.

Plant a tree. Plant a tree. Recycle.