Diandra N.

Global Warming Essay
Global warming is a growing problem that needs to be resolved not only by Americans but around world. Everyone in the world should contribute to help making out atmosphere healthy. Global warming is the increase in the average temperature of the Earth's near-surface air and oceans in recent decades and its projected continuation. The atmosphere has a natural supply of "greenhouse gases." They capture heat and keep the surface of the Earth warm enough for us to live on. Without the greenhouse effect, the planet would be an uninhabitable, frozen wasteland.

Before the Industrial Revolution, the amount of carbon dioxide (CO 2 ) and other greenhouse gases released into the atmosphere was in a rough balance with what could be stored on Earth. Natural emissions of heat-trapping gases matched what could be absorbed in natural sinks. For example, plants take in CO 2 when they grow in spring and summer, and release it back to the atmosphere when they decay and die in fall and winter .

Industry took off in the mid-1700s, and people started emitting large amounts of greenhouse gases. Fossil fuels were burned more and more to run our cars, trucks, factories, planes and power plants, adding to the natural supply of greenhouse gases. The gases—which can stay in the atmosphere for at least fifty years and up to centuries—are building up beyond the Earth's capacity to remove them and, in effect, creating an extra-thick heat blanket around the Earth. The result is that the globe has heated up by about one degree Fahrenheit over the past century—and it has heated up more intensely over the past two decades.

If one degree doesn't sound like a lot, consider this: the difference in global average temperatures between modern times and the last ice age—when much of Canada and the northern U.S. were covered with thick ice sheets—was only about 9 degrees Fahrenheit. So in fact one degree is very significant—especially since the unnatural warming will continue as long as we keep putting extra greenhouse gases in the atmosphere.

Already, people have increased the amount of CO 2 , the chief global warming pollutant, in the atmosphere to 31 percent above pre-industrial levels. There is more CO 2 in the atmosphere now than at any time in the last 650,000 years. Studies of the Earth’s climate history show that even small changes in CO 2 levels generally have come with significant shifts in the global average temperature. Scientists expect that, in the absence of effective policies to reduce greenhouse gas pollution, the global average temperature will increase another 2.0 degrees Fahrenheit to 11.5 degrees Fahrenheit by 2100.

Even if the temperature change is at the small end of the predictions, the alterations to the climate are expected to be serious: more intense storms, more pronounced droughts, coastal areas more severely eroded by rising seas. At the high end of the predictions, the world could face abrupt, catastrophic and irreversible consequences. Scientists are no longer debating the basic facts of climate change. In February 2007, the thousands of scientific experts collectively known as the Intergovernmental Panel on Climate Change (IPCC) concluded that there is greater than 90 percent likelihood that people are causing global warming. The Arctic is warming up faster than any other region. Because it plays a vital role in cooling the rest of the globe, the effects of this warming will be felt worldwide, not just on remote tundra.

Nineteenth-century explorer Fridtjof Nansen called the Arctic "nature's great ice temple," a place teeming with roaming polar bears and a forbidding landscape frozen since "the earliest dawn of time." But today, one cannot venture far enough north to escape global warming. The region has heated up nearly twice as fast as the rest of the globe over the past 50 years, according to a 2004 study assessing climate change in the Arctic. Land-based ice such as glaciers, ice sheets and permafrost and floating ice are vanishing, and the ongoing thaw has profound ramifications for the rest of the world.

The Arctic is critical to the globe's climate and influence temperatures everywhere.  It sounds counter-intuitive, but the Arctic plays a primary role in distributing heat around the world through what is known as the "heat pump." The ocean's currents circulate heat throughout the world, through a system known as the "great conveyor belt." Two main forces keep the conveyor moving: winds and ocean density differences. The Arctic is key to the density differences.

The conveyor belt's critical points are where surface waters plunge into deep waters. This happens only in a few places, two of which are in the North Atlantic. As the ocean surface waters cool in the far north, they become denser and sink toward the bottom of the ocean. There, the cold water flows toward the equator. This combination of sinking and flow helps drive the ocean conveyor. Because the cold waters that flow south must be replaced, warm surface currents flow farther north and deliver warmth to places far north. Without the ocean conveyor's heat pump, Europe's temperate climate would be much colder.

Global warming is changing that key spot in the North Atlantic where the surface waters plunge. A mix of increased precipitation, river run-off and melting ice—all related to climate change—is making surface waters in the north less salty and dense, weakening this major pump in the ocean's natural circulation. Also speeding up the Earth's warming is the loss of Arctic ice. Like a mirror, ice bounces sunlight back toward space, preventing sunlight from heating the surface. Winds carry the cooler air down from Canada into the U.S., cooling our climate.

Open water and bare soil are not as bright as ice and snow, so they absorb heat instead of reflecting it. When ice melts, the Earth's darker surfaces are exposed and thus absorb more solar energy. This extra heat melts even more ice, which leads to even more dark surfaces and absorption. This is what scientists call a positive feedback loop. Once the loop gets going, it tends to keep going—and to speed up. Less ice means less cooling much faster.

Burning fossil fuels to power our homes and run our cars creates global warming pollution. Big and small changes can add up and make a real difference in the fight against global warming. Home energy accounts for 21 percent of America's global warming pollution. If we make smart choices, we can cut more pollution than the entire emissions of over 100 countries! When it comes to global warming, how and what we drive are two of our most powerful choices. Transportation is the biggest source of U.S. carbon dioxide emissions, more than factories or homes. Even if you have already reduced your driving and electricity use, there's more you can do. You can neutralize the rest of your pollution—through offsets. When you buy offsets, you essentially pay someone to reduce or remove global warming pollution in your name. For example, when you buy 10 tons of carbon offsets, the seller guarantees that 10 fewer tons of global warming pollution go into the atmosphere. While the pollution you produce yourself is the same, you get the credit for that 10-ton reduction.