Atmosphere and Climate Change

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Atmosphere and Climate Change
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Climate

• Weather is the conditions that occur in the
  atmosphere are over a short period of time.
• Climate is how the atmosphere "behaves" over
  relatively long periods of time.
• When we talk about climate change, we talk about
  changes in long-term averages of daily weather.

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Past Climate Change

• The Earth's climate has changed throughout
  history.
• From glacial periods (or "ice ages") where ice
  covered significant portions of the Earth to
  interglacial periods where ice retreated to the
  poles or melted entirely - the climate has
  continuously changed.

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Past Climate Change

• Scientists have been able to piece together a
  picture of the Earth's climate dating back
  decades to millions of years ago by analyzing a
  number of substitute, or "proxy," measures of
  climate.

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Past Climate Change

• Examples of proxy measures include
• ice cores
• boreholes
• tree rings
• glacier lengths
• pollen remains
• ocean sediments
• studying changes in the Earth's orbit around the
  sun.

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Past Climate Change

• Causes of Change Prior to the Industrial Era
  (pre-1780)
• Changes in the Earth's orbit
• Changes in the sun's intensity
• Volcanic eruptions
• Changes in ocean currents

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Past Climate Change

• The Last 2,000 Years
• During the last 2,000 years, the climate has been
  relatively stable.
• Scientists have identified three departures from
  this stability, known as the Medieval Warm
  Period, the Little Ice Age and the Industrial Era

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Past Climate Change

• Prior to the Industrial Era,  the Medieval Warm
  Period and Little Ice Age had defined the upper
  and lower boundaries of the climate's recent
  natural variability and are a reflection of
  changes in climate drivers (the sun's variability
  and volcanic activity) and the climate's internal
  variability (referring to random changes in the
  circulation of the atmosphere and oceans).

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Recent Climate Change

• Since the Industrial Revolution (around 1750),
  human activities have substantially added to the
  amount of heat-trapping greenhouse gases in the
  atmosphere.
• The burning of fossil fuels and biomass (living
  matter such as vegetation) has also resulted in
  emissions of aerosols that absorb and emit heat,
  and reflect light.

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Factors That Determine Climate

• Elevation or Altitude
• Prevailing global wind patterns
• Latitude and angles of the suns rays
• Topography
• Distance from the equator
• Ocean circulation patterns
• Volcanic activity

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The Ozone Layer

• "The ozone layer" refers to the ozone within
  stratosphere, where over 90 of the earth's ozone
  resides.

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The Ozone Layer

• The ozone layer absorbs a portion of the
  radiation from the sun, preventing it from
  reaching the planet's surface.
• Most importantly, it absorbs the portion of
  ultraviolet light called UVB.
• UVB has been linked to many harmful effects,
  including various types of skin cancer,
  cataracts, and harm to some crops, certain
  materials, and some forms of marine life.

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The Ozone Layer

• The ozone layer absorbs 97-99 of the sun's high
  frequency ultraviolet light , light which is
  potentially damaging to life on earth.
• Every 1 decrease in the earths ozone shield is
  projected to increases the amount of UV light
  exposure to the lower atmosphere by 2.

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Chemicals That Cause Ozone Depletion

• Chlorofluorocarbons (CFCs)
• used as refrigerants, solvents, foam blowing
  agents, fire extinguishing agents
• CFCs have atmospheric lifetimes long enough to
  allow them to be transported by winds into the
  stratosphere.
• Because they release chlorine or bromine when
  they break down, they damage the protective ozone
  layer.

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The Ozone Hole

• CFCs, HCFCs, carbon tetrachloride, methyl
  chloroform, and other gases release chlorine
  atoms, and halons and methyl bromide release
  bromine atoms
• It is these atoms that actually destroy ozone.
• It is estimated that one chlorine atom can
  destroy over 100,000 ozone molecules before it is
  removed from the stratosphere.

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Protecting the Ozone Layer

• Montreal Protocol on Substances That Deplete the
  Ozone Layer
• International treaty designed to protect the
  ozone layer by phasing out the production of a
  number of substances believed to be responsible
  for ozone depletion.
• Since the Montreal Protocol came into effect, the
  atmospheric concentrations of the most important
  chlorofluorocarbons and related chlorinated
  hydrocarbons have either leveled off or decreased

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Global Warming

• Global warming is the increase in the average
  temperature of Earth's near-surface air and
  oceans since the mid-20th century and its
  projected continuation.

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The Greenhouse Effect

• Energy from the Sun drives the Earth's weather
  and climate.
• The Earth absorbs energy from the Sun, and also
  radiates energy back into space.
• However, much of this energy going back to space
  is absorbed by greenhouse gases in the
  atmosphere

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The Greenhouse Effect

• Because the atmosphere then radiates most of this
  energy back to the Earths surface, our planet is
  warmer than it would be if the atmosphere did not
  contain these gases.
• Without this natural "greenhouse effect,"
  temperatures would be about 60ºF lower than they
  are now, and life as we know it today would not
  be possible.

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Greenhouse Gases

• Carbon dioxide
• Water vapor
• Methane
• Nitrous oxide
• Fluorinated gases
• Hydrofluorocarbons, perfluorocarbons, and sulfur
  hexafluoride

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Carbon Dioxide

• Carbon dioxide enters the atmosphere through the
  burning of fossil fuels (oil, natural gas, and
  coal), solid waste, trees and wood products, and
  also as a result of other chemical reactions
  (e.g., manufacture of cement).
• Carbon dioxide is also removed from the
  atmosphere (or sequestered) when it is absorbed
  by plants as part of the biological carbon cycle.

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Carbon Dioxide (non-energy related) Emissions

• Cement manufacture
• calcium carbonate is heated to produce lime
• In 1998, the United States manufactured an
  estimated 85.5 million metric tons of cement,
  resulting in the direct release of carbon dioxide
  containing about 10.6 million metric tons of
  carbon into the atmosphere.

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Measuring Carbon Dioxide

• The rise of carbon dioxide gas in our atmosphere
  has been measured continuously since 1958.

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Methane Emissions

• Sources include energy production and consumption
  such as
• coal mining
• natural gas systems
• Waste management
• landfill gas
• Agriculture
• manure management
• cattle (enteric fermentation)
• rice cultivation

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Nitrous Oxide (N2O) Emissions

• Agricultural soil management
• nitrogen fertilization
• Mobile sources
• Acidic acid production
• used to make nylon

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Expected Consequences of GHG Concentration
Increases

• Temperature Global temperatures are rising.
• Observations collected over the last century
  suggest that the average land surface temperature
  has risen 0.45-0.6C (0.8-1.0F) in the last
  century.

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Expected Consequences of GHG Concentration
Increases

• Rising Sea Level
• Hotter temperatures mean ice -- glaciers, sea ice
  and polar ice sheets -- is melting, increasing
  the amount of water in the world's seas and
  oceans.

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Expected Consequences of GHG Concentration
Increases

• Shrinking Glaciers
• In the span of a century, glaciers in Montana's
  Glacier National Park have deteriorated from 150
  to just 35.
• And the Himalayan glaciers that feed the Ganges
  River, which supplies drinking and irrigation
  water to 500 million people, are reportedly
  shrinking by 40 yards (37 meters) each year.

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Montana's Glacier National Park
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Expected Consequences of GHG Concentration
Increases

• Heat Waves
• Extreme heat waves are happening two to four
  times more often now, steadily rising over the
  last 50 to 100 years, and are projected to be 100
  times more likely over the next 40 years.

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Expected Consequences of GHG Concentration
Increases

• Storms and Floods
• Warm waters give hurricanes their strength, and
  scientists are correlating the increase in ocean
  and atmospheric temperatures to the rate of
  violent storms.

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Expected Consequences of GHG Concentration
Increases

• Drought
• As the climate warms, experts estimate drought
  conditions may increase by at least 66 percent
  source Scientific American.
• An increase in drought conditions leads quickly
  to a shrinking water supply and a decrease in
  quality agricultural conditions.

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Expected Consequences of GHG Concentration
Increases

• Disease
• Warmer temperatures along with associated floods
  and droughts are encouraging worldwide health
  threats by creating an environment where
  mosquitoes, ticks, mice and other
  disease-carrying creatures thrive.

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Expected Consequences of GHG Concentration
Increases

• Economic Consequences
• Consumers face rising food and energy costs along
  with increased insurance premiums for health and
  home.
• Governments suffer the consequences of diminished
  tourism and industrial profits, soaring energy,
  food and water demands, disaster cleanup and
  border tensions.

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Expected Consequences of GHG Concentration
Increases

• Loss of Biodiversity
• As many as 30 percent of plant and animal species
  alive today risk extinction by 2050 if average
  temperatures rise more than 2 to 11.5 degrees F
  (1.1 to 6.4 degrees C) sources EPA, Scientific
  American.
• Such extinctions will be due to loss of habitat
  through desertification, deforestation and ocean
  warming, as well as the inability to adapt to
  climate warming.

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Expected Consequences of GHG Concentration
Increases

• Destruction of Ecosystems
• Changing climatic conditions and dramatic
  increases in carbon dioxide will put our
  ecosystems to the test, threatening supplies of
  fresh water, clean air, fuel and energy
  resources, food, medicine and other matters we
  depend upon not just for our lifestyles but for
  our survival.

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Coral Bleaching
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