Rachel S .

Global warming is the measurable increase in the average temperature of Earth’s atmosphere, oceans, and landmasses. This temperature increase is caused by greenhouse gases in the atmosphere, which trap radiant energy, or heat provided by the Sun, by the greenhouse effect.

The radiation from the Sun that penetrates the atmosphere and warms Earth’s surface is called short-wave radiation. Because this short-wave radiation is absorbed by Earth’s surface, it releases some of this heat as long-wave infrared radiation. Most of this long-wave infrared radiation goes back out to space, but some of it stays trapped in Earth’s atmosphere by greenhouse gases. These gases make up less than 1 percent of the atmosphere, and are the only gases that can give the Earth any kind of insulation. All life relies on the greenhouse effect, and without it, the average surface temperature of the planet would be about -18°C (0°F), and the Earth would be covered in ice.

There are many different types of greenhouse gases. Some occur naturally in the environment, and others are a result of human activities. These include water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Water vapor is the most abundant greenhouse gas in the atmosphere, and it comes from the evaporation of oceans, lakes, and rivers. Unlike the other greenhouse gases, water vapor is not affected by human activities.

Carbon dioxide is the second most abundant greenhouse gas in the atmosphere, and it is constantly circulating in the environment through a natural process called the carbon cycle. It is naturally released into the atmosphere by natural processes including the respiration of animals, the eruptions of volcanoes, and the decaying or burning of plants or other organic materials. It can also leave the atmosphere when absorbed by water, or through photosynthesis in which plants use light to convert carbon dioxide into sugars that they use as food. This then results in oxygen being released. The amount of carbon dioxide being released into the atmosphere can be affected by human activity as well by the burning of fossil fuels (coal, oil, and natural gases), solid wastes, and wood. Since 1750, the levels of carbon dioxide have risen by 35 percent, mainly from the burning of fossil fuels. These activities are causing carbon dioxide to be released faster and in larger amounts than the Earth’s natural processes can remove it.

Methane is a greenhouse gas that enters the atmosphere through the process of coal mining, the production and transportation of natural gases and oil, rotting organic matter in landfills, rice paddies, wetlands, and certain animals, and live plants release a small amount of it as well. Also, methane is released from melting permafrost in the tundra of Alaska, Siberia, and other subpolar regions. Scientists are concerned because the top layers of permafrost have increased, which will cause more methane to be released, and the more methane that will be released, the more it will contribute to warming and melting in the future. This is what scientists call a feedback process.

Nitrous oxide is a powerful greenhouse gas that is released mainly by the burning of fossil fuels. It traps almost 300 times more heat than the same amount of carbon dioxide would. The concentration of nitrous oxide has increased by 18 percent in the atmosphere since the Industrial Revolution, and it contributes nearly a tenth as much to global warming as carbon dioxide.

Ozone is partially a natural greenhouse gas, and the ozone layer is found in the upper atmosphere. It protects all life on Earth from the Sun’s ultraviolet radiation, and some chemicals can destroy ozone molecules which causes the depletion of the ozone layer. Ozone is also human made, but in the lower atmosphere, as it is a component of smog. This is formed from nitrogen oxides and gases emitted by automobiles and industrial sources, and it can damage vegetation, kill trees, irritate lung tissue, and destroy rubber. Smog contributes about a fourth as much as carbon dioxide to global warming, however it is usually located in industrialized areas of the world.

Scientists are making many predictions as to how global warming will affect weather, glacial ice, sea levels, agriculture, and wildlife; but some of these changes have already been observed. These include the fact that the weather patterns have been becoming less predictable and more violent. For example, the intensity of hurricanes has gotten more extreme since the 1970s. Also, polar regions are supposedly going to heat up more than the other regions, causing the size and amount of glaciers to decrease. The Arctic temperatures have already increased twice as much as the global average over the past few decades, and the sea ice during the summer has declined by 15 to 20 percent in the last 30 years. This is making it difficult for polar bears, seals, and walrus to live, which depend on sea ice to survive. This melting of glaciers is also significantly contributing to the sea level rise. During the 20 th century, sea level rose from 10 to 25 centimeters, and it is projected that by the end of the 21 st century, it will rise from 28 to 58 centimeters. Scientists believe that the melting of polar ice and glaciers is going to raise sea level so much that it will eventually flood some coastal regions, and even entire islands. Scientists also predict that global warming will cause growing seasons to be longer in some areas, which may increase agricultural projection, but not in the same places that crops grow currently.

Scientists predict that if the level of future greenhouse gas emissions continues to rise, there will be a further warming of 2.4 to 6.4°C by 2100. However, if greenhouse gas emissions lower, it is predicted that the temperature will peak around 2050, and then fall. This would cause there to be a further warming of 1.1 to 2.9°C by the year 2100.

I feel that global warming is a serious issue, and I wish that people would give it the attention it deserves. It is after all, a phenomenon which will potentially affect life as we know it on earth, more than wars or terrorist attacks. Therefore, the global community needs to work together to find solutions before it is too late.