Ch' 11'2 Human Activity and Climate Change

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Ch. 11.2 Human Activity and Climate Change

• Climate change ? the change in long-term weather
  patterns in certain regions.
• Global warming refers to a world-wide increase
  in average temperature, but is only one aspect of
  climate change.
• Several ice ages have occurred in the past
  million years.
• Both the causes and effects of global warming are
  unknown and controversial.

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Greenhouse Effect

• As greenhouse gases (e.g. CO2) increase, they
  absorb more heat reflected back from the earth,
  warming the atmosphere.
• Human activities increase some greenhouse gases.
• Greenhouse gases include water vapour, CO2, N2O,
  CH4, and CFCs.

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Carbon Dioxide

• CO2 levels have increased greatly in the past 200
  years.
• Since the Industrial Revolution, humans have
  greatly increased their overall use of fossil
  fuels, which release CO2 when burned.
• Deforestation has changed carbon sinks, such as
  forests, into carbon sources.
• Many people are attempting to reduce CO2
  emissions by using alternative energy sources or
  by reducing their energy use.
• Carbon offsets, such as wind farms, can be
  purchased
• to offset CO2 emissions.

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Methane

• Methane is very efficient at trapping thermal
  energy.
• 25X more efficient than CO2
• Methane is produced by bacteria breaking down
  wastes in oxygen-free environments, animals
  digesting
• plant matter, rice paddies (and other natural
  wetlands),
• and the burning of fossil fuels.

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Nitrous Oxide and Ozone

• Nitrous oxide, N2O, is the third largest
  contributor to the greenhouse effect.
• Even though there are only small amounts, it has
  300X more global warming potential than CO2.
• N2O comes from bacteria, fertilizers, and
  improper disposal of human and animal waste.

• Ozone is an important UV radiation blocker in the
  stratosphere.
• At lower altitudes, however, it is a very
  powerful greenhouse gas.
• This ozone comes from solar radiation reacting
  with pollution from the burning of fossil fuels,
  and is released from photocopiers and certain air
  conditioners.

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CFCs (Chlorofluorocarbons)

• Halocarbons, used as refrigerants, are strong
  greenhouse gases.
• Chlorofluorocarbons (CFCs) are the best-known
  halocarbons.
• Halocarbons ? ozone layer depletion.
• Cooling Units Use CFCs Some Aerosols Use CFCs

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Albedo and Climate

• The albedo at Earths surface affects the amount
  of solar radiation that region receives.
• Changes in a regions albedo - for example, snow
  cover melting earlier in the season than it did
  previously - Could result in climate change.
• Forests have a low albedo. Deforestation
  increases albedo.
• Forests also emit large amounts of water vapour,
  which reflects solar radiation back into space.
• Deforestations effects on climate change are
  unknown.

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Role of Science

• Computer models of Earths climate.
• Most show that a decrease in the production of
  greenhouse gases is necessary to stop the
  apparent global warming trend.
• General Circulation Models (GCMs) use data from
  multiple locations over long periods of time.
• Can look at changes in greenhouse
• gases, albedo, ocean currents, winds
• and surface temperatures.
• Can forecast weather, analyse climate
• and make predictions.
• Use past information to predict
• future conditions.

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International Cooperation

• The United Nations World Meteorological
  Organization ? Intergovernmental Panel on Climate
  Change (IPCC) to address global concerns about
  climate change and global warming (formed in 1988
  with 130 countries)
• The IPCC examines possible
• climate change, highlights the
• causes, and suggests solutions.
• Treaties to reduce greenhouse
• gas production are voluntary,
• which means some countries
• dont honour their pledge.

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Global Impacts of Climate Change
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Impact of Climate Change on

• Temperatures are increasing (average increase
  0.5ºC to 1.5ºC).
• Arctic regions are losing permafrost and ice
  cover on oceans.
• Growing seasons are getting longer and more
  precipitation is falling in the spring (possible
  drought in later summer).
• Rise in sea levels.
• Glaciers are melting (less drinking water).
• Fisheries could be very negatively affected.
• Pollution ? health issues.

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Temperature Change Predictions for Canada
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Climate Change in B.C.
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Climate Change in B.C.
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Strategies for Addressing Climate Change

• Although climate change is a controversial issue,
  our actions now are important.
• Improving our environmental approach will help,
  no matter how dramatic climate change actually
  is.
• Not acting could result in huge problems.
• The United Nations suggests the precautionary
  principle, better safe than sorry.
• Relatively small changes could have large
  positive impact on the climate in Canada.
• Reduce vehicle greenhouse gas emissions.
• Reduce industrial greenhouse gas emissions.
• Increase use of energy-efficient products.
• Improve indoor air quality.

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