READ: Climate Change

Pollution

Did you ever see a sky without contrails?

In the three days after the terrorists attacks on September 11, 2001, jet airplanes did not fly over the United States. Without the gases from jet contrails blocking sunlight, air temperature increased 1°C (1.8°F) across the United States. This is just one of the effects air pollution has on the environment.

Smog Effects on the Environment

All air pollutants cause some damage to living creatures and the environment. Different types of pollutants cause different types of harm.

Particulates

Particulates reduce visibility. In the western United States, people can now ordinarily see only about 100 to 150 kilometers (60 to 90 miles), which is one-half to two-thirds the natural (pre-pollution) range on a clear day. In the East, people can only see about 40 to 60 kilometers (25-35 miles), about one-fifth the distance they could see without any air pollution (Figure below).

Particulates reduce the amount of sunshine that reaches the ground, which may reduce photosynthesis. Since particulates form the nucleus for raindrops, snowflakes, or other forms of precipitation, precipitation may increase when particulates are high. An increase in particles in the air seems to increase the number of raindrops, but often decreases their size.

By reducing sunshine, particulates can also alter air temperature as mentioned above. Imagine how much all of the sources of particulates combine to reduce temperatures. What affect might this have on global warming?

Ozone

Ozone damages some plants. Since ozone effects accumulate, plants that live a long time show the most damage. Some species of trees appear to be the most susceptible. If a forest contains ozone-sensitive trees, they may die out and be replaced by species that are not as easily harmed. This can change an entire ecosystem, because animals and plants may not be able to survive without the habitats created by the native trees.

Some crop plants show ozone damage (Figure below). When exposed to ozone, spinach leaves become spotted. Soybeans and other crops have reduced productivity. In developing nations, where getting every last bit of food energy out of the agricultural system is critical, any loss is keenly felt.

Oxides

Oxide air pollutants also damage the environment. NO2 is a toxic, orange-brown colored gas that gives air a distinctive orange color and an unpleasant odor. Nitrogen and sulfur-oxides in the atmosphere create acids that fall as acid rain.

Lichen get a lot of their nutrients from the air so they may be good indicators of changes in the atmosphere such as increased nitrogen. In Yosemite National Park, this could change the ecosystem of the region and lead to fires and other problems.

http://www.ck12.org/earth-science/Effects-of-Air-Pollution-on-the-Environment/lesson/Effects-of-Air-Pollution-on-the-Environment/r18/

Climate Change

Global Climate Change

Another major problem caused by air pollution is global climate change. Gases such as carbon dioxide from the burning of fossil fuels increase the natural greenhouse effect. This raises the temperature of Earth’s surface.

Causes of Climate Change

The average global temperature  has been rising since the end of the Pleistocene which was about 11700 years ago, with some ups and downs, of course. Rising temperatures are natural for this time period. But natural causes cannot explain all the warming that's been happening in recent decades. There is some other factors at work.

Recent global warming is due mainly to human actions. The actions involve releasing greenhouse gases into the atmosphere. 

What Is the Greenhouse Effect?

The greenhouse effect is a natural feature of Earth’s atmosphere. It occurs when gases in the atmosphere radiate the sun’s heat back down to Earth’s surface (see Figure below). Otherwise, the heat would escape into space. Without the greenhouse effect, Earth’s surface temperature would be far cooler than it is. In fact, it would be too cold to support life as we know it.

Global Warming

Global warming refers to a recent increase in Earth’s average surface temperature (see Figurebelow). During the past century, the temperature has risen by almost 1°C (about 1.3°F). That may not seem like much. But consider that just 10°C is the difference between an ice-free and an ice-covered Earth.

Most scientists agree that global warming is caused by more carbon dioxide in the atmosphere (see Figure below). This increases the greenhouse effect. There is more carbon dioxide mainly because of the burning of fossil fuels. Destroying forests is another cause. With fewer forests, less carbon dioxide is removed from the atmosphere by photosynthesis.

http://www.ck12.org/biology/Global-Climate-Change/lesson/Global-Climate-Change/r25/

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Climate Change and Ecosystems

Effects of Climate Change

Already many effects of global warming are being seen. As Earth has warmed sea ice has melted. This has raised the level of water in the oceans (See image below).

The extent of Arctic sea ice in summer has been decreasing rapidly. The ice pictured is the sea ice minimum in 2011 (See below ). The line that traces outside the pictured ice is the median minimum ice for 1979–2000. Notice how much smaller the ice coverage was in 2011 compared to the normal 1979-2000 average.

For more information about global climate change, visit NASA’s Climate Change website. http://climate.nasa.gov/  Click on “Facts” in the upper right corner for data on evidence, causes, effects, and scientific consensus related to global climate change. 

How has global warming affected Earth and its life? Some of its effects include:

• Decline in cold-adapted species such as polar bears.
• Melting of glaciers and rising sea levels.
• Coastal flooding and shoreline erosion.
• Heat-related human health problems.
• More droughts and water shortages.
• Changing patterns of precipitation.
• Increasing severity of storms.
• Major crop losses.

This video discusses some of the consequences from changes in ecosystems:

 

http://www.ck12.org/biology/Global-Climate-Change/lesson/Global-Climate-Change/r25/

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Summary

Summary

• Gases such as carbon dioxide from the burning of fossil fuels increase the natural greenhouse effect. This is raising the temperature of Earth’s surface, and is called global warming.
• An increase in particulates may reduce photosynthesis, increase precipitation, and reduce temperatures.
• Ozone may damage native plants and some crop plants by slowing growth or damaging leaves.
• Nitrogen and sulfur-oxides are pollutants. They also create acids in the atmosphere that fall as acid rain.