anthropogenic sources of climate change

Anthropogenic

Sources of

Climate Change

Major Anthropogenic Sources

• CO2

• Aerosols• Cement manufacturing• Land use• Ozone depletion• Animal agriculture• Deforestation

CO2 e

miss

ions

• Fossil Fuel combustion and other human activities emit 30 Gigatons of CO2 into the atmosphere annually

• Natural processes emit 770 Gigatons of CO2 into the atmosphere annually

• The 4% of CO2 emissions humans produce over a long period of time will inhibit Earth’s ability to radiate heat to the upper atmosphere

Indu

stria

l Re

volu

tion• Period from the 18th to the 19th

century where major changes in agriculture, manufacturing, mining, transportation, and technology had a profound effect on the socioeconomic and cultural conditions

• Introduction of steam power fuelled primarily by coal

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Indu

stria

l Rev

olut

ion

• Increased use of machinery powered by burning coal established dramatic increases in production capacity

• By 2005 global atmospheric concentrations of CO2 were 35% higher than they were before the Industrial Revolution

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What are

Aerosols? A colloid suspension of fine solid particles or liquid droplets in a gas Examples:

CloudsAir pollution (smog)

Reflect or absorb sunlight, which either cools or warms the atmosphere

In general, scientists believe aerosols have acted to combat climate change

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Key Groups of

Aerosols

Sulfates

Black Carbon

Mineral Dust

Organic Carbon

Nitrates

Sea Salt

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NASA

NASA

NASA

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Sources of

Anthropogenic Aerosols

• Fossil fuel combustion

• Biomass burning• Automobiles• Incinerators• Smelters• Power plants

• Deforestation• Overgrazing• Dust • Cigarettes• Stoves• Fireplaces• Candles

FYI:10% of aerosols are

anthropogenic

• Produced in industrial areas • Eastern U.S. (New York, Pittsburgh)• Europe (Berlin, London)

• Anthropogenic emissions have increased in recent decades with increase in urbanization and industrialization in Asia

Sources of Anthropogenic Aerosols

Cem

ent

• Substance that sets and hardens independently & can bind other materials together• Crucial component in

buildings and roads• No viable recycling

potential

Cement Manufacturing

Calcium Carbonate is a key ingredient of cement

CaCO3 → CaO + CO2

Accounts for 5% of anthropogenic CO2 emissions

900 kg of CO2 is emitted for every 1000 kg of cement produced!!

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Land Use

NASA reports that “scientists estimate that between one-third and one-half of our planet's land surfaces have been transformed by human development”

A large body of research has documented the major role of land use and land cover change with variability in climate

Hum

an U

se o

f Lan

d

Urbanization Suburbanization

DeforestationIrrigating desert land

Damming riversResource extraction

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Pote

ntia

l Effe

cts

Thunderstorm frequency Change in water cycle

Change in energy budget

Active area of research …

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Ozone Cycle

Ozone prevents harmful

UV light from passing

through Earth’s

atmosphere

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Ozone

Depletion• Steady decline

of 4% per decade of stratospheric ozone

• Springtime decrease in stratospheric ozone over polar regions (ozone hole)

NASA accessed via Wikipedia

Two separate depletion events observed since late 1970’s

In both cases, ozone is destroyed by a reaction with halocarbon refrigerants (CFC’s, freons, and halons)

CFC’s = Chlorofluorocarbons

Image is a prediction of what

would happen if CFC’s were not

banned

NASA accessed via Wikipedia

Mont

real

Pr

otoc

ol

International treaty designed to phase out production of substances (CFC’s) believed to be responsible for ozone depletion

Signed in 1987 by 46 countries

If the protocol is followed, the ozone layer could recover by 2050

Notice any trends?

Animal Agriculture

(Globally) ruminant animals produce about 80 million metric tons of methane

This represents 28% of the anthropogenic methane emissions

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Defo

rest

atio

n

Removal of a forest where the land is converted to a non-forest use• Farms• Ranches• Urban use

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Defo

rest

atio

n

Plants use CO2 for photosynthesis

CO2 + H2O + energy from sun C6H12O6 + O2

Fewer plants leads to an increase in CO2 in the atmosphere

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Current Research Says…

Deforestation in the tropics accounts for nearly 20% of carbon emissions due to human activities

Maintaining forests as carbon sinks will make a significant contribution

to stabilizing atmospheric greenhouse gas concentrations