Global Climate Change

Global Climate Change

Carmela Ariane D. Aliazas BS Chemistry 311

What is Global Climate Change? Global climate change is a change in the long-term weather patterns that characterize the regions of the world. The term "weather" refers to the short-term (daily) changes in temperature, wind, and/or precipitation of a region. Weather is influenced by the sun. The sun heats the earth's atmosphere and its surface causing air and water to move around the planet.

Some of the sun's incoming long wave radiation is reflected back to space by aerosols. Aerosols are very small particles of dust, water vapor, and chemicals in Earth's atmosphere. In addition, some of the sun's energy that has entered Earth's atmosphere is reflected into space by the planet's surface. The reflectivity of Earth's surface is called albedo. Both of these reflective processes have a cooling affect on the planet.

Greenhouse Effect Energy from the Sun that makes its way to the Earth’s surface can have trouble finding its way back out to space. This is because of a natural process called the greenhouse effect. Without the greenhouse effect, Earth’s temperature would be below freezing. However, Earth’s greenhouse effect is getting stronger as we add more greenhouse gases to the atmosphere. And that is warming the climate of our planet.

Heat is radiated into the atmosphere from the Earth’s surface, which is warmed by sunlight. As the heat makes its way back to space, much of it is absorbed by greenhouse gases in the atmosphere. Greenhouse gases are larger than most other molecules in the atmosphere, and that makes them able to absorb heat. They radiate the heat back to the Earth's surface, to another greenhouse gas molecule, or out to space.

Sometimes during this Century, the amount of the greenhouse gas carbon dioxide in the atmosphere is expected to double. Other greenhouse gases like methane and nitrous oxides are increasing as well. The quantity of greenhouse gases is increasing as fossil fuels are burned, releasing the gases and other air pollutants into the atmosphere. Greenhouse gases also make their way to the atmosphere from other sources. Farm animals, for example, release methane gas as they digest food. As cement is poured and hardens, it releases carbon dioxide.

• With more greenhouse gases in the air, heat passing through on its way out of the atmosphere is more likely to be stopped. The added greenhouse gases absorb the heat. They then radiate this heat. Some of the heat will head away from the Earth, some of it will be absorbed by another greenhouse gas molecule, and some of it will wind up back at the planet’s surface again. With more greenhouse gases, heat will stick around, warming the planet.

• Greenhouse gases are released into the air from many sources. This pie chart shows where they were coming from in 2004

Albedo • The amount of energy reflected by a surface is called albedo. Albedo is measured on a scale from zero to one (or sometimes as a percent). – Very dark colors have an albedo close to zero (or close to 0%). – Very light colors have an albedo close to one (or close to 100%).

• Because much of the land surface and oceans are dark in color, they have a low albedo. They absorb a large amount of the solar energy that gets to them, reflecting only a small fraction of it. Forests have low albedo, near 0.15. Snow and ice, on the other hand, are very light in color. They have very high albedo, as high as 0.8 or 0.9, and reflect most of the solar energy that gets to them, absorbing very little.

• Earth’s climate depends on the amount of solar radiation that is reflected back out to space and the amount that is absorbed. If Earth’s climate is colder and there is more snow and ice on the planet, more solar radiation is reflected back out to space and the climate gets even cooler. On the other hand, when warming causes snow and ice to melt, darker colored Earth surface and ocean are exposed and less solar energy is reflected out to space causing even more warming. This is known as the ice-albedo feedback.

• Clouds have an important effect on albedo too. They have a high albedo and reflect a large amount of solar energy out to space. Different types of clouds reflect different amounts of solar energy. If there were no clouds, Earth’s average albedo would drop by half.

•

This picture of the Andes Mountains between Chile and Argentina in South America was taken from the International Space Station in December 2000. Glaciers and snow top many of the high mountain peaks. Lakes in the valleys between mountains collect the water that melts from the snow and ice each spring and summer. Scientists have found that the smaller glaciers in this area are melting quickly as the Earth becomes warmer.

Effects of Air Pollutants • Air pollution operates on a variety of scales, from the personal to the global and has serious consequences for the environment and human health.

Effects to People Our lungs are our personal link to the atmosphere. In a pollutionfilled environment, toxicity, concentration, and exposure time are maximized. Those most at risk include infants, the elderly, and those already at risk for lung disease. Mortality and morbidity statistics should remind us of our social responsibility concerning clean air legislation. People spend the vast majority of their time indoors where pollution levels may be 10 to 40 times higher than outdoors. Asbestos, Radon, carbon monoxide, and secondhand tobacco smoke are just a few of the airborne toxic pollutants that we encounter in high concentrations indoors.

Effects to the Community The immense amount of particulates, chemicals, and waste heat in highly populated urban areas can cause significant meteorological changes. Temperature inversions can cause stagnant conditions for periods ranging from several hours to several days. Urban heat islands have emerged along with the growth of cities. Polluted air over cities can contain as many as 1 million cloud condensation nuclei and can change precipitation patterns downwind.

• Acid deposition is also a regional or trans-boundary pollution issue. Emissions from anthropogenic sources account for about 70 percent of the sulfur and 88 percent of the NOx in the United States. They increase the acidity of the rainwater which leads to physical consequences, like the deterioration of buildings, as well as natural consequences. It has also increased the acidity of soil in forests, which destroys their plant life. Overall, air pollution causes serious meteorological, biological, and physical consequences.

• The SO2 and the NOx, which give rise to acid deposition, are emitted almost entirely by manmade sources. Although small amounts are emitted naturally by volcanoes or vegetation decay, the vast majority is released from coal burning mills or power plants.

Effects globally Air pollution can contribute to global climate change in a few different ways. Large amounts of carbon dioxide (CO2) in the atmosphere can lead to global warming due to the greenhouse effect. A significant rise in temperature will lead to the melting of polar ice caps. This event will then cause a rise in sea level, and the oceans will submerge major coastal cities. Conversely, the impenetrable amount of particulates in the air may block out the sun and its heat causing global cooling.

Health Effects • CO – Poor reflexes, ringing ears, headaches, dizziness, nausea, breathing difficulties drowsiness, reduced work capacity, comatose state

• Pb – kidney damage, reproductive system damage, nervous system damage

Health Effects • NOx – increased risk of viral infections, lung irritation, higher respiratory illness rates, airway resistance, some chest tightness, eye burning headache • O3 – respiratory system damage, reduced mental capacity, damage to cell lining, reduces effectiveness of the immune system, headaches, eye irritations, chest discomfort, breathing difficulties, chronic lung diseases, nausea

Health Effects • SO2 – aggravates heart and lung disease, increases the risk for respiratory illnesses, cancer

• PM10 – respiratory illnesses, aggravates heart disease