Earth Science Chapter 11.2 Climate Change

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.

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 CFC’s.

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.

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.

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.

CFC’s (Chlorofluorocarbons) Halocarbons, used as refrigerants, are strong greenhouse gases. Chlorofluorocarbons (CFC’s) are the best-known halocarbons. Halocarbons  ozone layer depletion. Cooling Units Use CFC’s Some Aerosols Use CFC’s

Albedo and Climate The albedo at Earth’s surface affects the amount of solar radiation that region receives. Changes in a region’s 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. Deforestation’s effects on climate change are unknown.

Role of Science Computer models of Earth’s climate. Most show that a decrease in the production of greenhouse gases is necessary to stop the apparent global warming trend. General Circulation Models (GCM’s) 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.

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 don’t honour their pledge.

Global Impacts of Climate Change

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.

Temperature Change Predictions for Canada

Climate Change in B.C.

Climate Change in B.C.

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.