Atmospheric and Climate Change Chapter 13

13-1 Climate and Climate Change Objectives 1. Explain the difference between weather and climate. 2. Identify four factors that determine climate. 3. Explain why different parts of the earth have different climates. 4. Explain what causes the seasons.

What Factors determine climate? Climate-long term prevailing weather (state of the atmosphere) Determined by: Latitude, atmospheric conditions, circulation patterns, oceanic patterns, local geography, solar activity, and volcanic activity.

Latitude Amount of solar energy that reaches the surface

Atmospheric circulation Warm air rises, cold air sinks Warm air holds more moisture Heat differences cause winds

Global Circulation Patterns Patterns are disrupted at the equator Cool air rises at the equator and is forced to the poles Air condenses and 30 degrees N and S Air sinks, causes water to evaporate from land Flows back to the poles or equator

Prevailing winds (westerlies) Blow from one direction most of the year Trade winds at 30 degrees N and S

Ocean Circulation patterns Hold vast amounts of heat Currents redistribute heat Cold and warm currents

El Nino – Southern Oscillation Short-term periodic change in the location of warm and cold currents in the Pacific ocean Winds in west Pacific become stronger and push warm water eastward Causes drought in Indonesia and Australia

Pacific Decadal oscillation La Nina - Water in the Pacific is colder than usual Pacific Decadal oscillation Long term change in currents

Local geography Mountain ranges Seasonal changes

Solar activity Increase UV and energy from the sun

Volcanic activity Releases gases (SO2)and dust into the atmosphere which affects weather

13-2 Ozone Shield Objectives 1. Explain how the ozone layer shields the Earth from much of the sun’s harmful radiation. 2. Explain how chlorofluorocarbons damage the ozone layer. 3. Explain the process by which the ozone hole forms. 4. Describe the damaging effects of ultraviolet radiation. 5. Explain why the threat to the ozone layer is still continuing today.

Ozone layer – ozone is concentrated Ozone Shield Ozone layer – ozone is concentrated O3 Absorbs UV – protects DNA of all living things

Chemicals that cause Ozone depletion CFC’s (chlorofluorocarbons) damages ozone Stable at surface but reacts in atmosphere destroys ozone molecules

Ozone hole Thinning of atmospheric ozone that occurs at the poles First report in 1985, but noticed in 1970’s

Chlorine reacts with ozone and destroys it Form in polar stratospheric clouds Can’t be replaced by ground level ozone

Affects Increased UV radiation Damages DNA Cancer Weaker immune system

Kills phytoplankton Harms amphibians, marine life, and plants

International agreements (Montreal Protocol) to eliminate CFC use Protection of Ozone International agreements (Montreal Protocol) to eliminate CFC use US pledged to ban all substances by 200 Did we do it?? Level is going down

It will be years before affects of programs can be measured because CFCs stay active for 60-120 years

13-3 Global Warming Objectives 1. Explain why Earth’s atmosphere is like the glass in a greenhouse. 2. Explain why carbon dioxide in the atmosphere appears to be increasing. 3. Explain why many scientists think that the Earth’s climate may be becoming increasingly warmer. 4. Describe what a warmer Earth might be like.

Greenhouse affect Traps sun energy Major greenhouse gases (absorb and radiate heat): Water vapor, CO2, CFCs, methane, and nitrous oxides

Keeling Started measuring CO2 levels 1958 – 314 ppm 2000 – 368 ppm Increased use of fossil fuels Levels have normal seasonal fluctuations

Glaciers and poles melt Increase of CO2 could cause a global rise in temperature (global warming) Glaciers and poles melt Sea level rise

Affects Increase of global temperature Rise of sea level Loss of coastline Agriculture Droughts or too much rain

Some scientists believe that the warming is part of natural climatic variability What is the evidence?

Consequences of a Warmer Earth These things could happen rather caused by nature or man…. Melting of ice and sea level rise Global weather patterns change Human health problems Agriculture Plants and animals

How do we reduce the risk? Reforestation Reduce dependence of on fossil fuels Reduce use of harmful chemicals International agreements - Kyoto Protocol