Download Understanding Our Environment

Global Climate Change
“Warming of the climate system is unequivocal.” – 1
International Panel on Climate Change, Fourth Report
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Outline
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The Atmosphere and Climate
 Convection Currents
 Greenhouse Effect
Weather
 Winds
 Frontal Systems
 Cyclonic Storms
Climate
 El Nino
 Climate Change
 Kyoto Protocol
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The Atmosphere and Climate
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Weather - daily temperature and moisture
conditions in a place
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Climate - a description of the long-term weather
pattern in a particular area
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The Atmosphere and Climate
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Troposphere
 Ranges in depth from 18 km over the equator to
8 km over the poles.
- All weather occurs here.
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The Atmosphere and Climate
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Stratosphere
 Very stable, calm layer of the atmosphere.
Used by aircraft.
From tropopause up to about 50 km
- Has almost no water vapor, but 1000X more
ozone than the troposphere
- Ozone absorbs ultraviolet light, which warms
upper part of stratosphere.
- Ozone protects all life on Earth since UV
radiation damages living tissues.
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The Atmosphere and Climate
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Mesosphere
 Middle Layer
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Thermosphere

Aurora borealis (northern lights)
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Layers of the Atmosphere
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Energy and the Greenhouse Effect
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Solar Radiation
 Of solar energy reaching outer atmosphere:
- 25% reflected
- 25% absorbed
- 50% reaches earth’s surface
 Of the solar energy that reaches the
surface, much is reflected (albedo):
- Fresh clean snow
90%
- Dark soil
3%
- Net average of earth
30% 8
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Energy and the Greenhouse Effect
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Most solar energy reaching the Earth is near
infrared (short wavelength).
 Energy reemitted by the earth is mainly far
infrared radiation (long wavelength, heat)
- Longer wavelengths are absorbed in the
lower atmosphere, trapping heat close to the
earth’s surface.
 Greenhouse Effect
 Atmosphere transmits sunlight while
trapping heat.
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Greenhouse Effect
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Gases in the atmosphere, especially carbon
dioxide and water vapor, are the substances
that retain heat.
Burning fossil fuels releases extra carbon
dioxide.
Deforestation destroys carbon sinks.
Positive feedback loop - poles covered with ice
reflect solar radiation back into space. Now that
ice is melting, open water is absorbing more
heat, which in turn is melting more ice, leading to
more warming.
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Sources of Greenhouse Gases
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Carbon Dioxide - fossil-fuel burning
- Atmospheric levels increasing steadily
- Most important cause of warming
Methane - ruminants, rice paddies
- Absorbs more infrared than CO2 .
Chlorofluorocarbons (CFC’s) - refrigerants
- Declined in developed countries, but now
produced in developing nations.
Nitrous Oxide - burning organic material
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Sources of Greenhouse Gases
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U.S. has less than 5% of world’s population but
produces 28% of carbon dioxide.
China, with 1.3 billion people, is second.
Japan and Europe produce half as much carbon
dioxide per person as the U.S.
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Measuring Carbon Dioxide in the
Atmosphere
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There is a carbon dioxide detector in
Mauna Loa in Hawaii.
 This allows measurements far away
from cities and forests.
 The winds over Mauna Loa have come
thousands of miles across the Pacific
Ocean, swirling and mixing as they
traveled.
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Measuring Carbon Dioxide in the Atmosphere
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Keeling’s first measurement, in March of
1958, was 0.0314 percent.
 Slightly higher in the winter.
 Slightly lower in the summer.
 Why? Photosynthesis
These levels have rose steadily over the
last 50 years.
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Carbon Dioxide Concentrations on Mauna Loa
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Weather Happens
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Weather - physical conditions in the atmosphere
(humidity, temperature, air pressure, wind and
precipitation) over short time scales
 Rain
- Air cools as it rises, and water condenses as
air cools.
- Cooling occurs because pressure decreases
as air rises.
- Condensation nuclei (tiny particles) must also
be present to have precipitation.
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Ocean Currents
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Warm and cold ocean currents strongly influence
climate conditions on land.
 As surface water moves, deep water wells up to
replace it.
- Ocean circulation also driven by differences in
water density due to temperature and
saltiness of water
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Frontal Weather
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Cold Front - boundary formed when cooler air
displaces warmer air
 Cold air is more dense, thus hugs ground and
pushes warm air up.
Warm Front - boundary formed when warm air
displaces cooler air
 Warm air is less dense and slides over cool air,
creating a long wedge-shaped band of clouds
and precipitation.
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Cyclonic Storms
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When rising air is laden with water vapor, latent
energy released by condensation intensifies
convection currents and draws up more warm air
and water vapor.
 Storm cell will exist as long as temperature
differential exists.
- Hurricanes (Atlantic)
 Katrina in 2005 caused greatest natural
disaster in North American history.
- Typhoons (Western Pacific)
- Cyclones (Indian Ocean)
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Cyclonic Storms
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Tornadoes - swirling funnel clouds
 Generated by “supercell” frontal systems
where strong dry cold fronts collide with warm
humid air
- Greater air temperature differences in the
spring, thus more tornadoes
 Downbursts - disorganized supercells that cause
downdrafts and straight line winds
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Cyclonic Storms
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Studying Climate
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Ice cores - collected from glaciers reveal light and
dark bands caused by annual snow accumulation
on glacier
 Gas bubbles can be analyzed for atmospheric
composition.
 Ash and sulfur deposits correlate with volcanic
eruptions.
 Vostok ice core gives us a record back 420,000
years.
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Climate
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Data show that:
 Abrupt climatic change has catastrophic effect on
living things as organisms are unable to adjust
before conditions exceed their tolerance limits.
Species may become extinct.
 There is a close correlation between carbon
dioxide concentration and temperature of the
atmosphere – allegedly.
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CLIMATE CHANGE IS A NATURAL
PROCESS
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Changes in climate have been observed
throughout history.
 There have been at least 5 major ice ages.
 The sun undergoes cycles where it
releases different amounts of energy.
 The Earth’s orbit can shift and tilt.
- Example: Magnitude 8.8 earthquake in
Chile shorted the Earth’s day by 1.26
millionths of a second.
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Climate
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Milankovitch Cycles - periodic shifts in Earth’s
orbit and tilt which change distribution and
intensity of sunlight
- Ice cores show drastic changes may have
occurred over short periods of time (years to
decades).
Volcanic eruptions can cool planet suddenly.
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Milankovitch Cycles
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Evidence of Global Warming
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According to the EPA, the global surface
temperature has increased 0.9°F since 1880.
 The Earth’s surface is currently warming at
a rate of about 0.29ºF/decade or
2.9°F/century.
 The eight warmest years on record (since
1880) have all occurred since 2001, with
the warmest years being 2005 and 2010.
 Arctic temperatures have increased twice
as fast as the rest of the Earth.
Source: http://epa.gov/climatechange/science/recenttc.html
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Global Warming
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Range of temperature increase predicted to be
from 1.1 to 6.4°C (2 to 11.5°F) by 2100 depending
on population growth, energy conservation, etc.
Best estimate is 1.8 to 4°C (3.2 to 7.8°F)
 To put that in perspective, there has been a 5
degree C rise since the middle of the last ice age
(about 20,000 years ago).
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Global Warming
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Most people will experience more extreme weather
including droughts, floods, heat waves and
hurricanes. These extremes have increased
significantly in the last decade.
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In the worst outcome, we could see millions of
human deaths.
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Sea levels are projected to rise 17-57 cm (7 to 23
in). If we do nothing, Greenland’s ice will melt and
raise sea levels 20 ft.
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Global Warming
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If Greenland’s ice melts, a great deal of land will be
flooded including:
 Most of Florida
 Some of the Gulf Coast
 Most of Manhattan
 Shanghai
 Hong Kong
 Tokyo
Opponents say cuts in greenhouse gas emissions
are too costly to business.
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Is Global Warming Human-Caused?
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The Intergovernmental Panel on Climate
Change (IPCC) released its fourth report in
2007.
Two important statements are made in the
summary of this report:
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“Warming of the climate system is unequivocal,
as is now evident from observations of increases
in global average air and ocean temperatures,
widespread melting of snow and ice, and rising
global average sea level. ”
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Is Global Warming Human-Caused?
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Second statement of the IPCC fourth report
summary:
 "Most of the observed increase in global average
temperatures since the mid-20th century is very
likely due to the observed increase in
anthropogenic greenhouse gas concentrations."
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Global Warming Timeline
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19th century: Beginning of industrial revolution
1958: Daily records of carbon dioxide levels start.
 Venus found to have surface temperatures above boiling
point.
1970: First Earth day.
1973: Arab embargo -- energy crisis.
1977: Scientific opinion converges on global warming as
the major climate risk.
1981: Warmest year on record.
1995: Reports on breaking up of Antarctic ice shelf.
1997: Kyoto protocol established.
1998: Strong El Nino produces warmest year on record.
2003: Deadly European heat wave / major ice
35 sheets
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2005
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Kyoto treaty goes into effect (not ratified by U.S.)
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Most active hurricane season in recorded history.
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Hurricane Katrina hits New Orleans.
Source: NOAA
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Hurricane Katrina
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Formed over the Atlantic in
August of 2005.
 Crossed Southern
Florida as a category 1
hurricane.
 Strengthened very
quickly over warm
waters of the Gulf of
Mexico
Made landfall over
Louisiana as a Category 3
hurricane.
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New Orleans
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Parts of New Orleans are below sea level.
The levees holding back the Mississippi river and
the shoreline were not maintained properly.
•Immediate
connections
were made
between global
warming, the
unusually warm
Gulf of Mexico,
and the
hurricane.
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2007-Present
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Severe drought hits Australia from 2007-2009, followed
by severe flooding in 2010.
Severe flooding in Pakistan in 2010.
In the last stages of President Bush’s term, global
warming was emphasized as a “scientific uncertainty”
In 2009, the U.S. House of Representatives passed a
bill meant to gradually limit the amount of carbon
dioxide produced. Stalled in the Senate.
In 2009, a series of emails from the researchers at the
University of Anglia were made public; some implied
data was being manipulated. This was nicknamed
“Climategate.”
2010 ties 2005 for the warmest year on record.
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Evidence of Climate Change is Overwhelming
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Ave. global temperature climbed 0.6°C (1°F) in last
century.
 19 of 20 warmest years in the past 150 yrs have
occurred since 1980.
 Hottest year since temperature records were
begun was 2005.
 Poles are warming fastest (4°C, 7°F over past 50
years). Permafrost is melting in Alaska and
Canada and houses, pipelines and trees are
being toppled.
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Global Warming Effects on Poles
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99% of sheet ice is located in Antarctica and
Greenland
Ice is melting worldwide, but especially
quickly at the poles.
 As a result…
- Ocean levels have risen about 3.0mm
per year in the 10 years.
- Adelle penguin population is down to 1/3
its normal level.
- Multiple populations of polar bears are
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declining.
Global Warming Effects on Glaciers
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Only about 1% of the world’s sheet ice is
located in temperate (non-polar) regions, but
these are close in proximity to human
populations.
 Himalayan glaciers are the sources of
Asia’s biggest rivers
 Biggest single source of water for the
entirety of southern Asia.
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Effects on the Hydrologic Cycle
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Surface temperatures are measurably
increasing. This effects the water cycle:
 Higher rate of evaporation (from land and
sea both)
 Warmer atmosphere is capable of holding
more water vapor.
- Higher likelihood of heavy precipitation
(both rain and snow) weather events.
Ocean temperatures are also increasing.
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Flawed Predictions
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A statement was published by a journal that
suggested the Himalayan glaciers could be
melted by 2035.
 These numbers were based on unrealistic
calculations and this prediction was
retracted.
 Many dismiss global warming claims in
general as a result of retractions such as
this.
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Global Warming will be Expensive
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At present, reducing greenhouse gas emissions
would cost 1% of world GDP according to Stern
report. (IPCC report says less than that.)
Energy production will need to be 80%
decarbonized by 2050 to stabilize climate.
 Ethical issue
 Poor will suffer the most; at least 200 million
people will become refugees of flood and
drought.
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Steps For Combating Climate Change
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Emissions trading
 markets already exist
Technology sharing
Reducing deforestation
Helping poorer countries adapt to climate change
 Tropical areas will not change as much as
middle and high latitudes.
 If both Greenland and Antarctica melt, 1/3 of
Earth’s population will be displaced.
- South Pacific island nation of Tuvalu already
abandoned due to climate change
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Combating Climate Change
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Insurance companies have $2 trillion in insured
properties along U.S. coastlines at risk from
flooding or severe storms.
Infectious diseases will increase as insects that
spread them are able to move to places where
they could not live before.
 West Nile, malaria, and dengue fever have
appeared in North America.
Melting of permafrost may release stores of
methane hydrate. Uncertainty about whether that
would increase warming or cooling.
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Controlling Greenhouse Emissions
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Reducing carbon dioxide levels
 Renewable energy sources
- Double average fuel economy
- Switch to efficient lighting and appliances
- Wind turbines
- Biofuels
 Capture and store carbon dioxide
- Planting vegetation
- Injection into wells
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Carbon Management
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Capturing and storing carbon dioxide
Build “trees” in which calcium hydroxide solution
would absorb carbon dioxide
Plant forests
Fertilize the oceans with iron to permit
phytoplankton growth, which would take up carbon
dioxide
Inject carbon dioxide underground or in ocean
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Synthetic “Trees” that Capture Carbon Dioxide
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Other Ideas?
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The stratoshield is an idea developed to combat
global warming by blocking some of the sunlight
entering the Earth’s atmosphere.
Inject sulfur dioxide or particulate pollutants into the
stratosphere.
 This would be too high in the atmosphere to be
directly breathed or cause acid rain.
 Blocks out just enough sunlight to bring global
temperatures down to acceptable ranges.
Another quick solution: dropping ice cubes into the
ocean.
Source: Futurama “Crimes51of the Hot”
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Progress Made
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United Kingdom has rolled back its CO2 emissions
to 1990 levels and is aiming for a 60% reduction by
2050.
Germany has reduced CO2 by 10%.
Denmark gets 20% of its electricity from windmills,
and plans to increase that to 50%.
China reduced its emissions 20% between 1997
and 2005.
(At its present rate, U.S. will be 25% above 1990
emissions in 5 years. No progress.)
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