What is the Climate Change October 31, 2009

Source–http://www.epa.gov/climate/climatechange/kids/climatesys.html

	It may seem hard to believe that people can actually change the Earth’s climate. But scientists think that the things people do that send greenhouse gases into the air are making our planet warmer.
Atmosphere The atmosphere covers the Earth. It is a thin layer of mixed gases which make up the air we breathe. This thin layer also helps the Earth from becoming too hot or too cold, much like clothing does for us.Weather systems, which develop in the lower atmosphere, are driven by heat from the sun, the rotation of the Earth, and variations in the Earth’s surface. Oceans Oceans cover about 70 percent of Earth’s surface. Their large mass and thermal properties, enable them to store vast quantities of heat. Oceans buffer and regulate temperature – energy absorbed or lost by the oceans results in a smaller surface temperature change than would occur over land. The atmosphere and ocean constantly exchange energy and matter. For example, water evaporates from the oceans into the atmosphere. This moisture then falls back to the Earth as precipitation – rain, snow, sleet, and even the morning dew on the grass. See an animation of how the planet’s water cycle is likely affected by climate change. (Macromedia Flash Version 5 or higher plug-in required) Land Land covers 27 percent of Earth’s surface, and land topographyinfluences weather patterns. For example, the weather in areas covered by mountains can be completely different than the weather in areas where the land is mostly flat. Ice Ice is the world’s largest supply of freshwater. It covers the remaining 3 percent of Earth’s surface including most of Antarctica and Greenland. Because ice is highly reflective and because of its insulating properties, ice plays an important role in regulating climate. Biosphere The biosphere is that part of Earth’s atmosphere, land, oceans that supports any living plant, animal, or organism. It is the place where plants and animals, including humans, live. Large quantities of carbon dioxide are exchanged between the land-based biosphere and the atmosphere as plants take in carbon dioxide and give off oxygen, and animals inhale oxygen and exhale carbon dioxide.

Explain the ‘The Greenhouse Effect’. October 31, 2009

The greenhouse effect is the retention by the Earth’s atmosphere in the form of heat some of the energy that arrives from the Sun as light. Certain gases, including carbon dioxide (CO₂) and methane (CH₄), are transparent to most of the wavelengths of light arriving from the Sun but are relatively opaque to infrared or heat radiation; thus, energy passes through the Earth’s atmosphere on arrival, is converted to heat by absorption at the surface and in the atmosphere, and is not easily re-radiated into space. The same process is used to heat a solar greenhouse, only with glass, rather than gas, as the heat-trapping material. The greenhouse effects happens to maintain the Earth’s surface temperature within a range comfortable for living things; without it, the Earth’s surface would be much colder.

Read more: http://science.jrank.org/pages/3148/Greenhouse-Effect.html#ixzz0VTb0CER9

Global Warming October 31, 2009

Global warming is an increase in the average temperature of the Earth’s atmosphere and oceans. The term is also used for the scientific theory ofanthropogenic global warming, which attributes much of the recently observed and projected global warming to a human-induced intensification of thegreenhouse effect. In this theory, the increased volumes of carbon dioxide and other greenhouse gases released mainly by the burning of fossil fuels, and, to a lesser extent, land clearing and agriculture, are the primary sources of warming. The natural greenhouse effect keeps the Earth 30 °C warmer than it otherwise would be; adding carbon dioxide to an atmosphere, with no other changes, will make a planet’s surface warmer. Current research is attempting to further illuminate and quantify the processes and factors that can affect temperature change, especially positive and negative feedback mechanisms

Temperature change is just one aspect of the broader subject of (human-induced) climate change. The scientific opinion on climate change, as expressed by the UN Intergovernmental Panel on Climate Change (IPCC) and explicitly endorsed by the national science academies of the G8 nations, is that the average global temperature has risen 0.6 ± 0.2 °C since the late 19th century, and that it is likely that “most of the warming observed over the last 50 years is attributable to human activities” [1]. A small minority of qualified scientists contest the view that humanity’s actions have played a significant role in increasing recent temperatures. Uncertainties do exist regarding how much climate change should be expected in the future, and a hotly contested political and public debate exists over what actions, if any, should be taken in light of global warming.Global warming is an increase in the average temperature of the Earth’s atmosphere and oceans. The term is also used for the scientific theory ofanthropogenic global warming, which attributes much of the recently observed and projected global warming to a human-induced intensification of thegreenhouse effect. In this theory, the increased volumes of carbon dioxide and other greenhouse gases released mainly by the burning of fossil fuels, and, to a lesser extent, land clearing and agriculture, are the primary sources of warming. The natural greenhouse effect keeps the Earth 30 °C warmer than it otherwise would be; adding carbon dioxide to an atmosphere, with no other changes, will make a planet’s surface warmer. Current research is attempting to further illuminate and quantify the processes and factors that can affect temperature change, especially positive and negative feedback mechanisms.

Based on basic science, observational sensitivity studies, and the climate models referenced by the IPCC, temperatures may increase by 1.4 to 5.8 °C between 1990 and 2100 [2]. This is expected to result in other climate changes including rises in sea level and changes in the amount and pattern ofprecipitation. Such changes may increase the frequency and intensity of extreme weather events such as floods, droughts, heat waves, and hurricanes, change agricultural yields, cause glacier retreat, reduced summer streamflows, or contribute to biological extinctions. Although warming is expected to affect the number and magnitude of these events, it is very difficult to connect any particular event to global warming.

The scientific consensus on global warming is that the Earth is warming, and that humanity’s greenhouse gas emissions are making a significant contribution. This consensus is summarized by the findings of the Intergovernmental Panel on Climate Change (IPCC). In the Third Assessment Report, the IPCC concluded that “most of the warming observed over the last 50 years is attributable to human activities“. This position was recently supported by an international group of science academies from the G8 countries and Brazil, China and India

Environmental refugees

Even a relatively small rise in sea level would make some densely settled coastal plains uninhabitable and create a significant refugee problem. If the sea level were to rise in excess of 4 metres almost every coastal city in the world would be severely affected, with the potential for major impacts on world-wide trade and economy. Presently, the IPCC predicts sea level rise of less than 1 meter through 2100, but they also warn that global warming during that time may lead to irreversible changes in the Earth’s glacial system and ultimately melt enough ice to raise sea level many meters over the next millenia. It is estimated that around 200 million people could be affected by sea level rise, especially in Vietnam, Bangladesh, China, India, Thailand, Philippines,Indonesia and Egypt.