Chapter 10 Global Climate Systems

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Chapter 10Global Climate Systems

• Geosystems 5e
• An Introduction to Physical Geography

Robert W. Christopherson Charlie Thomsen
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Key Learning Concepts

• After reading the chapter you should be able to
• Define climate and climatology and explain the
  difference between climate and weather.
• Review the role of temperature, precipitation,
  air pressure, and air mass patterns used to
  establish climatic regions.
• Review Köppens development of an empirical
  climate classification system and compare his
  with other ways of classifying climate.
• Describe the A, C, D, and E climate
  classification categories and locate these
  regions on a world map.
• Explain the precipitation and moisture efficiency
  criteria used to determine the B climates and
  locate them on a world map.
• Outline future climate patterns from forecasts
  presented and explain the causes and potential
  consequences.

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What is climate/climatology?

• Earth experiences an almost infinite variety of
  weather. Even the same location may go through
  periods of changing weather. This variability,
  when considered along with the average conditions
  at a place over time, constitutes climate. In a
  traditional framework, early climatologists
  faced the challenge of identifying patterns as a
  basis for establishing climatic classifications.
  Currently at the forefront of scientific effort
  by climatologists are developing models that can
  simulate the vast interactions and causal
  relationships of the atmosphere and hydrosphere.
  Climatology, the study of climate, involves
  analysis of the patterns in time and space
  created by various physical factors in the
  environment.

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How a climatic region synthesizes climate
statistics.

• Weather observations, gathered simultaneously
  from different points within a region, are
  plotted on maps and are compared to identify
  climatic regions. The weather components that
  combine to produce climatic regions include
  insolation, temperature, humidity, seasonal
  precipitation, atmospheric pressure and winds,
  air masses, types of weather disturbances, and
  cloud coverage. Similar climatic regions
  experience many of the same weather components.
• This site for example (http//www.cru.uea.ac.uk)
  has weather statistics spanning centuries.
  Lastly, the Climatic Research Unit at the
  University of East Anglia, England has
  information about current weather, climatic
  research and links to other climate research
  facilities around the world.

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How does the El Niño phenomenon produce the
largest interannual variability in climate? What
are some of the changes and effects that occur
world-wide?

• Normally, as shown in the next slide, the region
  off the West coast of South America is dominated
  by the northward-flowing Peru Current. These
  cold waters move toward the equator and join the
  westward movement of the south equatorial
  current. The Peru current is part of the overall
  counter-clockwise circulation that normally
  guides the winds and surface ocean currents
  around the subtropical high-pressure cell
  dominating the eastern subtropical Pacific.
  Occasionally, and for unexplained reasons,
  pressure patterns alter and shift from their
  usual locations, thus affecting surface ocean
  currents and weather on both sides of the
  Pacific. Unusually high pressure develops in the
  western Pacific and lower pressure in the eastern
  Pacific. This regional change is an indication
  of large-scale ocean-atmosphere interactions.
  Trade winds normally moving from east to west
  weaken and can be replaced by an eastward
  (west-to-east) flow. Sea-surface temperatures
  off South America then rise above normal,
  sometimes becoming more than 8 C (14 F) warmer,
  replacing the normally cold, upwelling,
  nutrient-rich water along Peru's coastline.

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El Niño wind and weather patterns across the
Pacific Ocean and TOPEX/Poseidon satellite image
for November 10, 1997 (white and red colors
indicate warmer surface water- a warm pool. (p.
279).
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How do radiation receipts, temperature, air
pressure inputs, and precipitation patterns
interact to produce climate types? (Examples from
a humid environment and from an arid environment.)

• Uneven insolation over Earth's surface, varying
  with latitude, is the energy input for the
  climate system. Daylength and temperature
  patterns vary diurnally (every day) and
  seasonally. The principal controls of temperature
  are latitude, altitude, land-water heating
  differences, and the amount and duration of cloud
  cover. The moisture input to climate is
  precipitation in the forms of rain, sleet, snow,
  and hail. Figure 10-2 (next slide) shows the
  worldwide distribution of precipitation and
  identifies several patterns.

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Worldwide average annual precipitation. Factors
like latitude, altitude, land-water heating
differences, and the amount and duration of cloud
cover determine the level of precipitation.
(p.278).
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The relationships among a climatic region,
ecosystem, and biome.

• One type of climatic analysis involves discerning
  areas of similar weather statistics and grouping
  these into climatic regions that contain
  characteristic weather patterns. Climate
  classifications are an effort to formalize these
  patterns and determine their related implications
  to humans. Interacting populations of plants and
  animals in an area forms a community. An
  ecosystem involves the interplay between a
  community of plants and animals and its abiotic
  physical environment. A biome is a large, stable
  terrestrial ecosystem.

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What are the differences between a genetic and an
empirical classification system?

• Classification is the process of ordering or
  grouping data or phenomena in related classes. A
  classification based on causative factorsfor
  example, the genesis of climate based on the
  interaction of air massesis called a genetic
  classification. An empirical classification is
  based on statistics or other data used to
  determine general categories. Climate
  classifications based on temperature and
  precipitation data are empirical classifications.

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Köppen's approach to climatic classification and
the factors used in this system

• Wladimir Köppen (1846-1940), a German
  climatologist and botanist, designed the Köppen
  classification system, widely used for its ease
  of comprehension. First published in stages,
  his classification began with an article on heat
  zones in 1884. By 1900, he was considering plant
  communities in his selection of some temperature
  criteria, using a world vegetation map prepared
  by French plant physiologist A. de Candolle in
  1855. Letter symbols then were added to
  designate climate types. Later he reduced the
  role played by plants in setting boundaries and
  moved his system strictly toward climatological
  empiricism. The first wall map showing world
  climates, co-authored with his student Rudolph
  Geiger, was introduced in 1928 and soon was
  widely used. The Köppen system is best viewed for
  what it is a valuable tool for general
  understanding, best limited to small scale
  hemispheric and world maps showing general
  climatic relationships and patterns. Most
  criticism of his system stems from asking the
  classification model to do what it was not
  designed to do, that is, produce specific
  climatic descriptions for local areas.

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The Thornthwaite system

• Some background on the Thornthwaite system
• The development of a simple method for the
  determination of potential evapo-transpiration
  led Thornthwaite to his climate classification
  system. Thornthwaite was critical of Köppen's
  choice of criteria for his climatic boundaries,
  and especially, the boundaries between the humid
  and dry climates. Temperature efficiency and
  precipitation effectiveness were concepts
  contributed by Thornthwaite. His 1948
  classification introduced a moisture index
  concept as a basis for classification.
  Thornthwaite's classification is marred only by
  its complexity and lack of widespread use.
  Otherwise, the system in several ways is more
  accurate than is the Köppen system in its
  depiction of the humid-dry boundaries, especially
  those in North America.

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Thornthwaite Contd

• The key to Thornthwaite's approach is that
  temperature and precipitation alone are not the
  most active factors in the distribution of
  vegetation rather, Thornthwaite regarded POTET
  (the amount of water needed for maximized plant
  growth) and its relation to precipitation and
  plant moisture needs as the critical factor.
  Whereas Köppen used average annual temperature
  and precipitation for the determination of a
  moisture index, Thornthwaite used POTET and
  established a moisture index based on
  calculations of water balance moisture surpluses
  and moisture deficits. The moisture index can
  range from 100 as a measure of the degree PRECIP
  exceeds POTET, to a low of 100, where no PRECIP
  is received. When the moisture index is at zero,
  it is at the midpoint along the boundary line
  between the humid and dry climates. Thornthwaite
  established five climate classifications arid,
  semiarid, subhumid, humid, and perhumid.

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The principal climate designations according to
Köppen. In which one of these general types do
you live? See next slide.

• Köppen Guidelines
• A Climate Tropical Climates
• B Climate Dry arid and semiarid climates.
• C Climate Mesoothermal climates.
• D Climate Microtheraml climates.
• E Climate Polar climates.
• H Climate Highland climate. Denotes cold
  climate due to elevation.

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Tropical Climates (A)
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Dry, Arid, and Semiarid Climates (B)  
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Mesothermal Climates (C)
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(No Transcript)
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Microthermal Climates (D)
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Polar Climates (E)
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Köppen Climate System (Fig. 10.5)
Figure 10.5
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Example, characterizing the tropical A climates
in terms of temperature, moisture, and location.

• The key temperature criterion for an A climate is
  that the coolest month must be warmer than 18C
  (64.4F), making these climates truly winterless.
  The consistent daylength and almost perpendicular
  Sun angle throughout the year generates this
  warmth. Subdivisions of the A climates are based
  upon the distribution of precipitation during the
  year. Thus, in addition to consistent warmth, an
  Af climate (tropical rain forest climate) is
  constantly moist, with no month recording less
  than 6 cm (2.4 in.) of precipitation. Indeed,
  most stations in Af climates receive in excess of
  250 cm (100 in.) of rainfall a year. Not
  surprisingly, the water balances in these regions
  exhibit enormous water surpluses, creating the
  world's largest stream discharges in the Amazon
  and Congo (Zaire) Rivers.

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Which of the major climate types occupies the
most land and ocean area on Earth?

• In terms of total land and ocean area, tropical A
  climates are the most extensive, occupying about
  36 of Earth's surface. The A climate
  classification extends along all equatorial
  latitudes, straddling the tropics from about 20
  N to 20 S and stretching as far north as the tip
  of Florida and south-central Mexico, central
  India, and southeast Asia.

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Mesothermal C climates occupy the second-largest
portion of Earth's entire surface. Description
(temperature, moisture, and precipitation
characteristics).

• The word mesothermal suggests warm and temperate
  conditions, with the coldest month averaging
  below 18C (64.4F) but with all months averaging
  above 0C (32F). The C climates, and nearby
  portions of the D climates, are regions of great
  weather variability, for these are the latitudes
  of greatest air-mass conflict. The C climatic
  region marks the beginning of true seasonality,
  with contrasts in temperature as evidenced by
  vegetation, soils, and human lifestyle
  adaptations. Subdivisions of the C classification
  are based on precipitation variability.

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Explaining the distribution of the humid
continental Cfa and Mediterranean dry-summer Csa
climates (part of the C mesothermal climate) at
similar latitudes and the difference in
precipitation patterns between the two types.
Also, the difference in vegetation associated
with these two climate types.

• Cfa climates are located in the eastern and
  east-central portions of the continents and are
  influenced during the summer by the maritime
  tropical air masses generated over warm coastal
  waters off eastern coasts. The warm, moist,
  unstable air forms convectional showers over
  land. In fall, winter, and spring, maritime
  tropical and continental polar air masses
  interact, generating frontal activity and
  frequent midlatitude cyclonic storms.

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Cfa/Csa continued.

• Across the planet during summer months, shifting
  cells of subtropical high pressure block
  moisture-bearing winds from adjacent regions. As
  an example, in summer the continental tropical
  air mass over the Sahara in Africa shifts
  northward over the Mediterranean region and
  blocks maritime air masses and cyclonic systems.
  This shifting of stable, warm-to-hot, dry air
  over an area in summer and away from these
  regions in the winter creates a pronounced
  dry-summer and wet-winter pattern. The
  designation s (hence Csa) specifies that at
  least 70 of annual precipitation occurs during
  the winter months.

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Which climates are characteristic of the Asian
monsoon region?

• Cwa or C (mesothermal) w (winter dry) a (hot
  summer, warmest month above 22C) climates are
  related to the winter-dry, seasonal pulse of the
  monsoons and extend poleward from the Aw
  (tropical savanna) climates. Köppen identified
  the wettest Cwa summer month as receiving 10
  times more precipitation than the driest winter
  month. Cherrapunji, India, receiving the most
  precipitation in a single year, is an extreme
  example of this classification. In that location
  the contrast between the dry and wet monsoons is
  most severe, ranging from dry winds in the winter
  to torrential rains and floods in the summer.
  Downstream from the Assam Hills, such heavy rains
  produced floods in Bangladesh in 1988 and 1991,
  among other years.

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How can a marine west coast Cfb climate type can
occur in the Appalachian region of the eastern
United States?

• An interesting anomaly relative to the marine
  west coast climate occurs in the eastern United
  States. Increased elevation in portions of the
  Appalachian highlands moderates summer
  temperatures in the Cfa humid continental
  classification, producing a Cfb marine west coast
  designation. Vegetation similarities between the
  Appalachians and the Pacific Northwest are quite
  noticeable, enticing many emigrants who relocate
  from the East to settle in this climatically
  familiar environment in the west.

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The climatic designation for the coldest places
on Earth outside the poles. What do each of the
letters in the Köppen classification indicate?

• The Dwc and Dwd microthermal subarctic climates
  occur only within Russia. Köppen selected the
  tertiary letter d for the intense cold of Siberia
  and north-central and eastern Asia it designates
  a coldest month with an average temperature lower
  than 38C (36.4F). A typical Dwd station is
  Verkhoyansk, Siberia. For four months of the year
  average temperatures fall below 34C (29.2F).
  Verkhoyansk frequently reaches minimum winter
  temperatures that are lower than 68C (90F).
  However, higher summer temperatures in the same
  area produce the world's greatest annual
  temperature range from winter to summer, a
  remarkable 63C (113.4F).

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Global Warming

• Significant climatic changes has occurred on
  Earth in the past and most certainly will occur
  in the future. There is nothing society can do
  about long-term influences that cycle Earth
  through swings from ice ages to warmer periods.
  However, our global society must address
  short-term changes that are influencing global
  temperatures within the life span of present
  generations.
• Record-high global temperatures dominated the
  past two decades, records for both land and ocean
  and for both day and night. 1998 was the
  all-time record year for warmth, 2001 was second
  and eclipsed the previous records set in 1997 and
  1995. Understanding the warming and all related
  impacts is an important applied topic of Earth
  systems science and the spatial analysis ability
  of physical geography. (Movie at the end of
  lecture).

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Global Temperatures
Figure 10.28
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1998 Temperature records.
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Carbon Dioxide Sources
Figure 10.29
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July 2029 Temperature Forecast
Figure 10.31
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Antarctic Peninsula Ice Disintegration
Figure 10.32
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(No Transcript)
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Potential Climate Change Impacts
Health Weather-related mortality Infectious
diseases Air-quality respiratory illnesses
Agriculture Crop yields Irrigation demands
Climate Changes
Forests Change in forest composition Shift
geographic range of forests Forest health and
productivity
Temperature
Precipitation
Water Resources Changes in water supply Water
quality Increased competition for water
Sea Level Rise
Coastal Areas Erosion of beaches Inundation of
coastal lands Costs to protect coastal communities
Species and Natural Areas Shift in ecological
zones Loss of habitat and species
Source EPA
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Global Warming Questions

• What is the potential climatic effects of global
  warming on polar and high-latitude regions. What
  are the implications of these climatic changes
  for persons living at lower latitudes?

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Answers

• Perhaps the most pervasive climatic effect of
  increased warming would be the rapid escalation
  of ice melt. The additional water, especially
  from continental ice masses that are grounded,
  would raise sea level worldwide. Scientists are
  currently studying the ice sheets of Greenland
  and Antarctica for possible changes in the
  operation of the hydrologic cycle, including
  snowlines and the rate at which icebergs break
  off (calve) into the sea. The key area being
  watched is the West Antarctic ice sheet, where
  the Ross Ice Shelf holds back vast grounded ice
  masses.
• Loss of polar ice mass, augmented by melting of
  alpine and mountain glaciers, will affect
  sea-level rise. A quick survey of world
  coastlines shows that even a moderate rise could
  bring change of unparalleled proportions. At
  stake are the river deltas, lowland coastal
  farming valleys, and low-lying mainland areas,
  all contending with high water, high tides, and
  higher storm surges. There will be both internal
  and international migration of affected
  populations, spread over decades, away from
  coastal flooding if sea levels continue to rise.

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How is climatic change affecting agricultural and
food production? Natural environments? Forests?
The possible spread of disease?

• Modern single-crop agriculture is more
  delicate and susceptible to temperature change,
  water demand and irrigation needs, and soil
  chemistry than is traditional multicrop
  agriculture. Specifically, the southern and
  central grain-producing areas of North America
  are forecast to experience hot and dry weather by
  the middle of the next century as a result of
  higher temperatures. An increased probability of
  extreme heat waves is forecast for these U.S.
  grain regions. Also, available soil moisture is
  projected to be at least 10 less throughout the
  midlatitudes over the next 30 years than present
  levels. Scientists are considering changing to
  late-maturing, heat-resistant crop varieties and
  adjusting fertilizer applications and irrigation.

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Contd

• Biosphere models predict that a global average of
  30 of the present forest cover will undergo
  major species redistribution, the greatest change
  occurring in high latitudes. Many plant species
  are already "on the move" to more favorable
  locations. Land dwellers must also adapt to
  changing forage. Warming is already stressing
  some embryos as they reach their thermal limit.
  Particularly affected are amphibians, whose
  embryos develop in shallow water. The warming of
  large bodies of water may benefit some species,
  and harm others.
• Recent studies suggest that climate change may
  affect health on a global basis. Populations
  previously unaffected by malaria,
  schistosomiasis, sleeping sickness, and yellow
  fever would be at greater risk in subtropical and
  midlatitude areas.

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What are the present actions being taken to delay
the effects of global climate change? What is the
Kyoto Protocol? The operation of the Conference
of the Parties? What is the current status of the
United States and Canadian government action on
the Protocol?

• A product of the 1992 Earth Summit in
  Rio de Janeiro, the largest environmental
  gathering of countries ever, was the United
  Nations Framework Convention on Climate
  Convention (FCCC). The leading body of the
  Convention is the Conference of the Parties (COP)
  operated by the countries that ratified the FCCC,
  some 170 by 1998. Subsequent meetings were held
  in Berlin (COP-1, 1995) and Geneva (COP-2, 1996).
  These meetings set the stage for COP-3 in Kyoto,
  Japan, December 1997, where 10,000 participants
  adopted the Kyoto Protocol by consensus. The
  latest gatherings were COP-6 held in the Hague in
  late 2000 and COP-7 in Marrakech, Morocco, in
  2001. Seventeen national academies of sciences
  endorsed the Kyoto Protocol. (For updates on the
  status of the Kyoto Protocol see
  http//www.unfccc.int/ resource/kpstats.pdf

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Contd

• The Protocol binds more developed countries to a
  collective 5.2 reduction in greenhouse gas
  emissions as measured at 1990 levels for the
  period 2008 to 2012. Within this group goal,
  various countries promised cuts U.S. 7 (the
  105th Senate leadership announced they would not
  ratify the Protocol), Canada 6, European Union
  8, Australia 8, among many others. The Group of
  77 countries plus China favor a 15 reduction by
  2010.
• The Protocol is far-reaching in scope, including
  calling for international cooperation in meeting
  goals, technology development and transfers,
  leniency for less developed countries, clean
  development initiatives, and emissions trading
  schemes between industrialized countries and
  individual industries. The goal, simply and
  boldly stated is to prevent dangerous
  anthropogenic interference with the climate
  system. In 2001 and 2002 the U.S. Administration
  abandoned the protocol process and the agreement
  reached at COP-7.
• This momentum lead to Earth Summit 2002
  (http//www.earthsummit2002.org/) in
  Johannesburg, South Africa, with an agenda
  including climate change, freshwater, gender
  issues, global public goods, HIV/AIDS,
  sustainable finance, and the five Rio
  Conventions.

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• Ten Steps to Reduce Your Global Warming Impact

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• Individual choices can have an impact on global
  climate change. Reducing your family's
  heat-trapping emissions does not mean forgoing
  modern conveniences it means making smart
  choices and using energy-efficient products,
  which may require an additional investment up
  front, but often pay you back in energy savings
  within a couple of years.

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• Since Americans' per capita emissions of
  heat-trapping gases is 5.6 tonsmore than double
  the amount of western Europeanswe can all make
  choices that will greatly reduce our families'
  global warming impact.

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1. The car you drive the most important personal
climate decision.

• When you buy your next car, look for the one with
  the best fuel economy in its class. Each gallon
  of gas you use releases 25 pounds of
  heat-trapping carbon dioxide (CO2) into the
  atmosphere. Better gas mileage not only reduces
  global warming, but will also save you thousands
  of dollars at the pump over the life of the
  vehicle. Compare the fuel economy of the cars
  you're considering and look for new technologies
  like hybrid engines.

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2. Choose clean power.

• More than half the electricity in the United
  States comes from polluting coal-fired power
  plants. And power plants are the single largest
  source of heat-trapping gas. None of us can live
  without electricity, but in some states, you can
  switch to electricity companies that provide 50
  to 100 percent renewable energy.

•                 

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3. Look for Energy Star.

• When it comes time to replace appliances, look
  for the Energy Star label on new appliances
  (refrigerators, freezers, furnaces, air
  conditioners, and water heaters use the most
  energy). These items may cost a bit more
  initially, but the energy savings will pay back
  the extra investment within a couple of years.
  Household energy savings really can make a
  difference If each household in the United
  States replaced its existing appliances with the
  most efficient models available, we would save
  15 billion in energy costs and eliminate 175
  million tons of heat-trapping gases.

                                  

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4. Unplug a freezer.

• One of the quickest ways to reduce your global
  warming impact is to unplug the extra
  refrigerator or freezer you rarely use (except
  when you need it for holidays and parties). This
  can reduce the typical family's carbon dioxide
  emissions by nearly 10 percent.

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5. Get a home energy audit.

• Take advantage of the free home energy audits
  offered by many utilities. Simple measures, such
  as installing a programmable thermostat to
  replace your old dial unit or sealing and
  insulating heating and cooling ducts, can each
  reduce a typical family's carbon dioxide
  emissions by about 5 percent.

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6. Light bulbs matter.

• If every family in the United States replaced one
  regular light bulb with an energy-saving model,
  we could reduce global warming pollution by more
  than 90 billion pounds, the same as taking 7.5
  million cars off the road. So, replace your
  incandescent bulbs with more efficient compact
  fluorescents, which now come in all shapes and
  sizes. You'll be doing your share to cut back on
  heat-trapping pollution and you'll save money on
  your electric bills and light bulbs.

                     
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7. Think before you drive.

• If you own more than one vehicle, use the less
  fuel-efficient one only when you can fill it with
  passengers. Driving a full minivan may be kinder
  to the environment than two midsize cars.
  Whenever possible, join a carpool or take mass
  transit.

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8. Buy good wood.

• When buying wood products, check for labels that
  indicate the source of the timber. Supporting
  forests that are managed in a sustainable fashion
  makes sense for biodiversity, and it may make
  sense for the climate too. Forests that are well
  managed are more likely to store carbon
  effectively because more trees are left standing
  and carbon-storing soils are less disturbed.

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9. Plant a tree.

• You can also make a difference in your own
  backyard. Get a group in your neighborhood
  together and contact your local arborist or urban
  forester about planting trees on private property
  and public land. In addition to storing carbon,
  trees planted in and around urban areas and
  residences can provide much-needed shade in the
  summer, reducing energy bills and fossil fuel
  use.

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10. Let policymakers know you are concerned about
global warming.

• Our elected officials and business leaders need
  to hear from concerned citizens. Sign up for the
  Union of Concerned Scientists Action Network to
  ensure that policymakers get the timely, accurate
  information they need to make informed decisions
  about global warming solutions.
• http//www.ucsaction.org/join/index.asp

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Movie Whats Up With the Weather?

• A look at the greenhouse effect and global
  warming. Explores the question of whether or not
  the global climate is altered by human activity.
• NOVA C2000
• WGBH Television Station Boston, Mass.