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Climate Change FAQs

What is global warming?
    Global warming generally refers to the recent heating of the planet, which is also known as climate change. Our earth has both warmed up and cooled down in its geological history. Average global temperatures have increased around 1 deg. Fahrenheit the past century. They are projected to rise at rates five to 10 times as fast this century, which is the most rapid increase in 10,000 years, the end of the last ice age. The scientific consensus is that human activities are to blame. If projections are correct, the 21st century will see a temperature increase roughly equal to or greater than the entire global warming after the ice age. And our warming is not from ice age temperatures, but on top of an already warm atmosphere. The speed of change itself raises concerns that plants, animals and human beings will not be able to adapt rapidly enough to the changes.

What causes global warming?
    Global warming is the result of the greenhouse effect, which is the product of greenhouse gases. They represent less than one percent of the Earth’s atmosphere but perform a vital role. By trapping the sun’s heat, they maintain the planet at an average temperature in the high 50s. Without them, the planet would hover around an uninhabitable 0 deg. F. Here’s how the greenhouse effect works: The sun’s rays arrive in the atmosphere as ultraviolet radiation, which comes in short waves so it slips right through the atmosphere to the surface. When the rays hit ground and water, they turn into heat, or infrared radiation, which reflects back out into the atmosphere as long waves. Those waves are caught by greenhouse gases, which are all composed of molecules that have three or more atoms. Over 99 percent the atmosphere is composed of smaller molecules. These “big” three-atom molecules catch the “big” waves of infrared rising into the atmosphere, trapping the heat and warming the planet. The problem now is that human activities are releasing too many three-atom molecules into the atmosphere, enhancing the natural greenhouse effect.

What are greenhouse gases and where do they come from?
    Water vapor is a greenhouse gas that rapidly circulates in and out of the atmosphere. The major greenhouse gas that humans are adding to the atmosphere is carbon dioxide, CO2, which remains in the atmosphere a century or more. The second largest greenhouse gas being emitted by humans is methane, CH4, which is around 20 times more powerful than CO2. Much of this comes from agricultural sources such as farm animals and rice paddies. Nitrous oxide is another large greenhouse contributor. CFCs, the ozone depleting substances that are now being phased out, as well as their replacement, HCFCs, are also powerful greenhouse gases. Roughly three-quarters of human-caused greenhouse warming comes from the burning of fossil fuels – coal, oil and gas. Most of the remainder comes from deforestation, primarily of the tropical rainforests.

Can we stop global warming?

    The best science indicates that to stabilize the climate, we must rapidly reduce human greenhouse emissions on the order of 70 percent. This is a huge task, but the longer we wait, the bigger the challenge when we finally get to it. Because the climate resembles a speeding train that takes a long time to slow, the longer we wait the greater the risk that we will set in motion natural forces we cannot stop. There are huge risks in waiting too long. The greenhouse effect could feed the greenhouse effect by unlocking huge amounts of greenhouse gases from natural ecosystems. The loss of tropical rainforests to drying and fires would release massive amounts of greenhouse gases, as would melting of Arctic tundras and heating of seabed sediments. Ironically, global warming could send the Earth back into the ice age by shutting off the Gulf Stream to the North Atlantic, which carries tropical heat north and keeps Europe 15 deg. F warmer than it would otherwise.

    Global warming is a train that is speeding up right now. First we need to slow the train, and then we need to stop it. We can do so by transforming our energy system from one based on fossil fuels to one based on natural, renewable energies including sun, wind, tides, plant growth and geothermal energy. We have the technology, but applying it will take a large investment by government and business. In shifting to clean energy, we will also eliminate much air pollution, and build new industries and a new basis of sustainable prosperity. If we move quickly to clean energy, stop deforesting the tropics and move to more sustainable agriculture, we will eliminate most greenhouse gases, and avert climatic catastrophe. This is one of the largest challenges humans have ever faced, but we are richer now in economy, technology and scientific knowledge than we ever have been before. We are well up to the task. We just have to recognize its critical importance to our future.

Wouldn’t it be pleasant to have milder temperatures, especially in colder regions?

    Global warming will have winners and losers, but most of us will be losers. Some of the hardest hit regions will be in the developing nations of the tropics, particularly in Africa, and since this is primarily a result of gases emitted by the rich nations, this is a global justice concern. Other big losers will be inhabitants of tropical islands who could lose their homes to rising seas and the Inuit peoples of the Arctic whose environment will melt right out from underneath them.

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