Human Impact on The Atmosphere The atmosphere provides

Human Impact on The Atmosphere

• The atmosphere provides gases that organisms need to survive, including O 2 and CO 2. • The atmosphere absorbs harmful UV radiation coming from space.

• Without the atmosphere, temperatures on Earth would not be stable. • The Greenhouse Effect is the way by which certain gases in the atmosphere absorb and reradiate thermal energy.

What is air pollution? • The contamination of the atmosphere by toxins from human and natural sources is called air pollution. • Air pollution can come from natural sources, such as volcanic eruptions, wildfires, and dust storms. • In cities and suburbs, most air pollution comes from the burning of fossil fuels.

• Air pollution can be classified as gases such as carbon monoxide (CO), sulfur dioxide (SO 2), and ground-level ozone. • Air pollution can also be classified as particulates. These are tiny particles of solids that are suspended in air. • The particulates from vehicle exhaust are a major cause of pollution in cities.

Pollutants from vehicle exhaust. • Vehicle exhaust is a common source of air pollution (CO, SO 2, HC) in urban areas. • Ground-level ozone is produced when sunlight reacts with vehicle exhaust and oxygen in the air. Ground-level ozone is harmful to all living things.

• Vehicle exhaust also produces smog. • Smog is a brownish haze that forms when ground-level ozone and vehicle exhaust react in the presence of sunlight.

• Smog can damage the lungs and irritate the eyes and nose.

Pollution and Acid Precipitation. • Precipitation that contains acids from air pollution is called acid precipitation. • Burning fossil fuels releases sulfur dioxide and nitrogen oxides into the air. • When these gases mix with water in the atmosphere, they form sulfuric acid and nitric acid.

• Sulfuric acid and nitric acid are strong acids. They can make precipitation so acidic that it is harmful to the environment.

Effects of Acid Rain. • Acid precipitation cause soil and water to become more acidic than normal. • Changes in soil acidity cause soil to lose some of the nutrients that plants need.

• Acid rain can also make lakes and streams more acidic and cause soils to release toxic metals into the water. • This can harm aquatic organisms.

Air Quality • Air quality is the measure of how clean or polluted the air is. • As pollution increases, air quality decreases. • Two major threats are vehicle exhausts and industrial pollutants.

• The Air Quality Index (AQI) is a number used to describe the air quality of an area. • The higher the AQI number, the more people are likely to have health problems linked to air pollution.

How are humans changing the Earth’s climate? • As a result of burning fossil fuels, the atmosphere today contains about 37 percent more carbon dioxide than it did in the mid-1700 s. • Average global temperatures have also risen in recent decades.

• It is hard to know exactly how much the extra greenhouse gases have changed temperatures. • Computer models designed to understand climate change predict that average global temperatures will continue to rise.

Predicted long term effects • Many changes on Earth have already been linked to higher temperatures. • Changes in rainfall patterns and rising sea levels will have many negative effects on life on Earth. • Such changes will likely have political and economic effects on the world.

The Ozone Layer. • Earth’s protective ozone layer is thinning over the polar regions, allowing more harmful ultraviolet radiation to reach Earth’s surface. • Chemicals called chlorofluorocarbons (CFCs) cause ozone to break down. CFCs once had many industrial uses, but now they are banned.

• Unfortunately, CFCs released in the atmosphere decades ago will stay there many more decades, breaking down more ozone.

Reducing air pollution • Everybody can help reduce air pollution in many different ways. • Energy conservation is one of the most important ways to reduce air pollution.

• Fossil fuels are the most commonly used energy resource. When fossil fuels are burned, they release pollution into the air. • If we use less energy, we burn fewer fossil fuels. • There are many ways to conserve energy. What can you do?