Ecology & Environmental Problems Dr. Ron Chesser Lecture #8 Environmental Disasters

ENHANCED GREENHOUSE EFFECT

Global Warming Global warming refers to a rise in average global temperature due to human activities: namely, the emissions of greenhouse gases produced by the burning of fossil fuels, and land-use changes like deforestation. Scientists predict that higher temperatures will probably be accompanied by an increase in extreme weather events, such as flooding and drought, as well as global sea-level rise. While the first signs of global warming are apparent now, a sharp reduction of greenhouse gas emissions can significantly slow global warming.

How hot will it get? There is a worldwide consensus among climate scientists that global average temperature has risen about 1°F (0.4°C- 0.8°C) in the past 140 years. According to the IPCC, Earth may warm by 2.5°F to 10.4°F ( °C) by the end of this century, potentially making our planet warmer than at any time since dinosaurs were dominant.

Global Warming The effects of global warming are already being seen. For example, in 1998 the world experienced many extreme weather-related disasters: Two thousand five hundred people drowned and 56 million were driven from their homes in China, due to the flooding of the Yangtze River. The monsoon season put two-thirds of Bangladesh under water for more than a month and left 21 million people homeless. In India, 3000 people died of heat-stroke. Hurricane Mitch hit Honduras with 180-mile-per-hour winds; it washed away an estimated 70% of all crops, killed 11,000 people, and left a third of the population homeless. Forty-five countries experienced severe droughts, a number of which were accompanied by runaway fires. A prolonged drought left Russia with its lowest grain harvest in 40 years. Healthy rainforests do not burn, but 1998 saw serious fires throughout Southeast Asia and the Amazon. Fires in southern Mexico were so extensive that they led to air quality alerts throughout Texas.

GLOBAL CHANGE Arctic ice 'melting from below

THE GREENHOUSE GASES Carbon Dioxide or CO 2 is the most significant greenhouse gas released by human activities, mostly through the burning of fossil fuels. It is the main contributor to climate change. Methane is produced when vegetation is burned, digested or rotted with no oxygen present. Garbage dumps, rice paddies, and grazing cows and other livestock release lots of methane. You can find nitrous oxide naturally in the environment but human activities are increasing the amounts. Nitrous oxide is released when chemical fertilizers and manure are used in agriculture. Halocarbons are a family of chemicals that include CFCs (which also damage the ozone layer), and other human-made chemicals that contain chlorine and fluorine

Emissions of Greenhouse Gases in the United States 2001 Summary

Sources of Nitrous Oxide

Greenhouse Gas Emissions

CO 2 INCREASES

Sources of Nitrous Oxide Emissions associated with nitrogen fertilization of soils Emissions from the solid waste of animals Industrial processes and wastewater treatment facilities fossil fuel combustion –82.7 percent comes from mobile sources, principally motor vehicles equipped with catalytic converters

Land Use and Forestry Forest lands in the United States are net absorbers of carbon dioxide from the atmosphere rate at which forests absorb carbon slows as the trees mature rate of reforestation has slowed SOURCES AND SINKS --

How are governments addressing this problem? International agreements have called for a reduction in the emissions of greenhouse gases to reduce the effects of future global warming. Over 100 countries, including the European Union, Canada and Japan, have ratified the Kyoto Protocol. The United States, the biggest emitter of greenhouse gases in the world, has refused to ratify the Kyoto Protocol.

GREENHOUSE EMMISSIONS The Kyoto Target

USA

RUSSIA

FRANCE

OZONE Ozone is primarily found in the atmosphere at varying concentrations between the altitudes of 10 to 50 kilometers. This layer of ozone is also called the ozone layer (depicted in yellow). Ozone protects life from the harmful effects of ultraviolet radiation. Without it life could not exist on Earth

Alternate Energy Sources