Global Changes in the Atmosphere Notes

Short-Term Climate Change We already know that an abrupt shift in ocean currents can lead to changes in normal climates. El Niño, translated as “The Child,” is named after the Christ child as the El Niño event is usually associated with late December. El Niño can bring heavy rains to some parts of the world, and droughts to others.

Short-Term Climate Change La Niña, on the other hand, is a period of colder than normal surface waters in the Pacific Ocean. La Niña is the opposite of El Niño. La Niña brings cold winters and greater precipitation to the Pacific Northwest of the United States.

Global Warming Most changes in the world climates are caused by natural factors. But recently scientists have observed climate changes that could be the result of human activities. This gradual heating of the atmosphere is known as global warming. Over the last 120 years, the average temperature in the troposphere, has risen about 0.7°C. Now, this may not seem like a lot, but a 6°C increase would create a world almost uninhabitable to humans. http://channel.nationalgeographic.com/channel/sixde grees/

Global Warming Earth’s surface is heated by energy from the sun. Some of the heat is radiated back into space. Certain gases in the atmosphere hold heat that is radiated from Earth. The process by which the gases trap heat energy is called the greenhouse effect. Normally, Earth maintains a balance of incoming solar radiation and outgoing heat loss. This is known as the radiation balance.

Global Warming The gases in the atmosphere that trap heat energy are called greenhouse gases. Greenhouse gases include carbon dioxide (CO2), water vapor (H20), and methane (CH4). Yes, even our domestication of animals contributes to greenhouse gases in the atmosphere.

Global Warming Human activities add CO2 to the atmosphere. For example, burning wood, coal, and oil adds CO2 to the air. Thank you, Industrial Revolution. Adding CO2 to the air increases the greenhouse effect. Increasing the greenhouse effect may be the cause of global warming. Some scientists predict that the level of CO2 could double by the year 2100. If that happens, then global temperatures could rise by several Celsius degrees.

Global Warming Global warming could have the following effects: Cooler places could become new farmlands. Creation of “dust bowls.” Warmer oceans = stronger hurricanes. Warmer water expands = sea level rise Melting glaciers/ice caps = sea level rise

Ozone Depletion Ozone (O3) in the atmosphere blocks ultraviolet (UV) radiation from the sun. The loss of ozone means more UV radiation reaches Earth’s surface. UV radiation can cause eye damage and skin cancer, In the 1970s, scientists noticed a hole in the ozone layer of the atmosphere. The hole became its largest in 2006, being almost the size of Africa.

Ozone Depletion A major cause of the ozone hole is a group of chemicals that were used in air conditioners, refrigerators, and spray cans (such as hair spray). The chemicals are called chlorofluorocarbons, or CFCs. These chemicals contain chlorine, fluorine, and carbon. When CFCs interact with O3 in the atmosphere, it breaks down the ozone into O2, or atmospheric oxygen.

Ozone Depletion The United States and other countries have cut down on the use of CFCs. On January 1, 1989, the Montreal Protocol went into affect. The Montreal Protocol is an international agreement to eliminate the use of specific CFCs. It has been signed by 197 nations and is hailed as “perhaps the single most successful international agreement to date...” At the moment, the ozone hole should be fully repaired by 2050.