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Effects of Global Warming

There is no doubt that a small group of thoughtful, committed citizens can change the world. Indeed, it is the only thing that ever has.

“Global warming will be the greatest environmental challenge in the 21st century.”
Albert Gore.

Is climate change really happening?
Scientists have been debating this question for about 20 years now. As one of the world’s leading climate scientists, Stefan Rahmstorf of Potsdam Institute for Climate Impact Research says, the current scientific view of global warming is “based on decades of research and thousands of studies. The extraordinary consensus reached is seen in the statements of many international and national professional bodies which have extensively and critically assessed the scientific evidence.”

Since records of the weather date back to only a hundred years or so, how can scientists confidently make claims that the climate has been changing over a much longer period? It turns out that Earth keeps a natural record of its own climate in many surprising ways. For example, as ice has formed year upon year at the poles, old ice has been buried underneath with bubbles of air trapped inside it. The bubbles act as a record of what the air was like on Earth when the ice formed—and thus what the climate was like in the years gone by. Using drills, scientists can extract ice cores (long thin pipes full of ice), study the air bubbles at different depths, and calculate how much carbon dioxide they contain. If they figure out how old the ice is, they can use an ice core as a kind of graph of how carbon dioxide has changed over time.

Scientists can also study changes in the climate using ocean sediments, samples of buried pollen, and other, once-living matter. Research like this can tell us what the climate was like hundreds of thousands of years ago. Although most scientists believe in global warming, it’s important to note that a minority do not. Some agree that Earth is warming but not that fossil-fuel burning and carbon dioxide emissions are responsible for this. The “climate-change skeptics” argue that increases in Earth’s temperature are not happening at all or may be caused by other things, including natural variations in the climate that have been happening for millennia. In recent years, however, fewer and fewer scientists have dissented from the widely held position that global warming and climate change are really happening. People could still be wrong about global warming—but that’s becoming increasingly.

What causes global warming?
Global warming is caused by a phenomenon known as the greenhouse effect. A greenhouse (or glasshouse) is good for growing things because it traps heat inside and stays hotter than the atmosphere around it.

Earth’s atmosphere behaves like a gigantic greenhouse, though it traps heat a different way. Gases high in the atmosphere, such as carbon dioxide and methane, behave like a giant piece of curved glass wrapped right round the planet.

The Sun’s rays (mostly visible light and short-wavelength, high-energy ultraviolet radiation) pass straight through this “greenhouse gas” and warm up Earth. The warming planet gives off heat energy (longer wavelength infrared radiation), which radiates out toward space. Some of this outgoing radiation does not pass through the atmosphere, but is reflected back down to Earth, effectively trapping heat and keeping the planet about 33 degrees hotter than it would otherwise be. This is called the natural greenhouse effect and it’s a good thing. Without it, the Earth would be much too cold to support the huge diversity of life that it hosts.

Sources:
http://www.explainthatstuff.com
http://www.pewclimate.org/global-warming-basics/kidspage.cfm