Download Understanding Our Environment

Global Warming
Climate change
how global warming works
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Current Evidence of Climate Change
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Precipitation increased 1% in last century.
Artic sea ice thinning.
Alpine glaciers retreating.
Coral reefs bleaching.
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Facts and Figures
Global warming, or climate change:
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Over the past century, the Earth has increased in temperature by
about .5 degrees Celsius and many scientists believe this is because
of an increase in concentration of the main greenhouse
gases: carbon dioxide, methane, nitrous oxide, and fluorocarbons .
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Average temperatures have climbed 1.4 degrees Fahrenheit (0.8
degree Celsius) around the world since 1880.
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The Arctic is feeling the effects the most. Average temperatures in
Alaska, western Canada, and eastern Russia have risen at twice the
global average, according to the multinational Arctic Climate Impact
Assessment report compiled between 2000 and 2004.
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The effects of climate change are evident
today and nowhere is this more true than in
the Arctic.
Melting sea ice leaves polar bears and other
arctic wildlife species treading water without
their critical habitat. Alaska’s ecosystems are
being dramatically altered by rising sea
levels, devastating wildfires, and melting
permafrost.
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Arctic ice is rapidly disappearing, and the
region may have its first completely ice-free
summer by 2040 or earlier.
Polar bears and indigenous cultures are
already suffering from the sea-ice loss.
Glaciers and mountain snows are rapidly
In the Northern Hemisphere, thaws also
come a week earlier in spring and freezes
begin a week later.
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Coral reefs, which are highly sensitive to small
changes in water temperature, suffered the worst
bleaching—or die-off in response to stress—ever
recorded in 1998, with some areas seeing bleach
rates of 70 percent.
Experts expect these sorts of events to increase in
frequency and intensity in the next 50 years as sea
temperatures rise.
• An upsurge in the amount of extreme weather
events, such as wildfires, heat waves, and strong
tropical storms, is also attributed in part to climate
change by some experts.
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Industrialization, deforestation, and pollution
have greatly increased atmospheric
concentrations of water vapor, carbon
dioxide, methane, and nitrous oxide, all
greenhouse gases that help trap heat near
Earth's surface.
• Humans are pouring carbon dioxide into the
atmosphere much faster than plants and
oceans can absorb it.
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Energy and the Greenhouse Effect
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Solar Radiation
 Solar energy not evenly distributed over the
globe.
 Of solar energy reaching outer atmosphere:
- 25% reflected
- 25% absorbed
- 50% reaches earth’s surface
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Green House Effect
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The greenhouse effect is the natural process
by which the atmosphere traps some of the
Sun's energy, warming the Earth enough to
support life or
The "greenhouse effect" is the heating of the
Earth due to the presence of greenhouse
gases.
Green house gases
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Greenhouse gases naturally blanket the Earth and
keep it about 33 degrees Celsius warmer than it
would be without these gases in the atmosphere.
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It is named this way because of a similar effect
produced by the glass panes of a greenhouse.
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Shorter-wavelength solar radiation from the sun
passes through Earth's atmosphere, then is
absorbed by the surface of the Earth, causing it to
warm.
Part of the absorbed energy is then reradiated
back to the atmosphere as long wave infrared
radiation.
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Most mainstream scientists believe a humandriven increase in "greenhouse gases" is
increasing the effect artificially.
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These gases persist in the atmosphere for
years, meaning that even if such emissions
were eliminated today, it would not
immediately stop global warming.
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Conventional Pollutants
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US Clean Air Act designated seven major
(conventional or criteria) pollutants for which
maximum ambient (Air around us) air levels are
mandated. EPA sets allowable limits for
concentrations of these pollutants:
 Sulfur Dioxide
 Carbon Monoxide
 Particulates
 Hydrocarbons
 Nitrogen Oxides
 Photochemical Oxidants
 Lead
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Human-Caused Global Climate Change
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IPCC (Intergovernmental Panel on Climate
Change (2001) released report stating
“recent changes in the world’s climate have
had discernable impacts on physical and
biological systems.”
 Concluded human activities must be at
least partially responsible.
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Controlling Greenhouse Emissions
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Switch to renewable energy sources such as
solar, wind, biomass etc.
CO2 is lives longer in the atmosphere than
Methane and other greenhouse gases.
Capture and Store CO2:
 Increase plantations of trees and farmland
 Inject CO2 into underground strata or deep
ocean (Read pg 208 for details).
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CLEAN AIR LEGISLATION
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Clean Air Act (1963) - First national air
legislation pollution control.
Clean Air Act (1970) rewrote original Act.
 Identified critical pollutants.
 Established ambient air quality standards
mainly:
Primary Standards – to protect human
health
Secondary Standards –to protect materials,
environment, and comfort.
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Clean Air Act
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Since 1970 the Clean Air Act has been modified &
amended: Revision in1990 and have addressed
principal problems :
 Acid Rain
 Urban Smog
 Toxic Air Pollutants
 Ozone Protection
 Marketing Pollution Rights
 Fugitive emissions of volatile organics
 Ambient ozone, soot, and dust.
 NOx emissions (Nitrogen oxides)
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International Climate Negotiations
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Kyoto Protocol (1997) signed in Japan as a follow up of the
earth’s summit(1992) in Rio de Janeiro
 160 nations agreed to roll back carbon dioxide, methane,
and nitrous oxide emissions about 5% below 1990 levels
by 2012.
 Also included 3 other green house gases to be reduced:
hydrofluorocarbon (CFC), perfluorocarbon and sulphur
hexafluoride.
 The protocol sets different limits for different countries,
depending on their output before 1990,however poorer
countries like China and India were exempeted from their
emission limit to allow thse countries to develop.
 They also argued that wealthier countries created this
mess and they should sort out this problem.
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how global warming works
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