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Anthropogenic
Sources
of
Climate
Change
Major Anthropogenic Sources
• CO2
• Aerosols
• Cement manufacturing
• Land use
• Ozone depletion
• Animal agriculture
• Deforestation
CO
2 e
mis
sions
• 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
Indust
rial
Revo
luti
on• 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
Wikipedia | GNU
Indust
rial R
evo
luti
on
• 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
Wikipedia | Public Domain
What a
re
Aero
sols?
A colloid suspension of fine solid particles or liquid droplets in a gas
Examples:Clouds
Air pollution (smog)
Reflect or absorb sunlight, which either cools or warms the atmosphere
In general, scientists believe aerosols have acted to combat climate change
Wikipedia | Public Domain
Key G
roups o
f
Aero
sols
Sulfates
Black Carbon
Mineral Dust
Organic Carbon
Nitrates
Sea Salt
Wikipedia | Public Domain
Wikipedia | Creative Commons
NASA
NASA
NASA
Wikipedia | Creative Commons
Source
s of
Anth
ropogenic A
ero
sols
• 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!!
Wikipedia | Creative Commons
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 La
nd
Urbanization
SuburbanizationDeforestation
Irrigating desert land
Damming riversResource extraction
Wikipedia | GNU
Pote
nti
al E
ffect
s
Thunderstorm frequency
Change in water cycle
Change in energy budget
Active area of research …
Wikipedia | Creative Commons
Ozo
ne C
ycle
Ozone prevents harmful
UV light from passing
through Earth’s
atmosphere
Wikipedia | Public Domain
Ozo
ne
Deple
tion
• 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
Montr
eal
Proto
col
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?
Anim
al A
gricu
lture
(Globally) ruminant animals produce about 80 million metric tons of methane
This represents 28% of the anthropogenic methane emissions
Wikipedia | Public Domain
Defo
rest
ati
on
Removal of a forest where the land is converted to a non-forest use
• Farms
• Ranches
• Urban use
Wikipedia | Public Domain Wikipedia | GNU
Defo
rest
ati
on
Plants use CO2 for photosynthesis
CO2 + H2O + energy from sun C6H12O6 + O2
Fewer plants leads to an increase in CO2 in the atmosphere
Wikipedia | Creative Commons
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