|Stewart, Robert. Oceanography in the 21st Century. 25 May 200.||"Earth's surface is 33 degrees warmer than it would be if it had no atmosphere. A planet the size of earth at earth's distance from the sun, and in thermodynamic equilibrium with solar radiation, would have a surface temperature of −18 degrees C. Earth's average surface is 15 degrees C, or 33 degrees C warmer. This increase in temperature is due mostly to greenhouse gases in earth's atmosphere."||15 °C|
|Hart, John. Global Warming. MSN Encarta Premium. 1997-2005.||"The average surface temperature of Earth is about 15 °C (59 °F)."||15 °C|
|A look at the Detrimental Impact of the Greenhouse Effect. essaysample.com, 2004.||"These gases--water vapor (H2O), carbon dioxide (CO2), and methane (CH4)--keep ground temperatures at a global average of about 15 degrees C (60 degrees F)."||15 °C|
|Sagan, Carl. The Atmospheric and Climatic Consequences of Nuclear War. 1984.||"The upper dashed horizontal line shows the average temperature of the Earth (13 °C or 56 °F), and the lower dashed horizontal line shows the freezing point of pure water (0 °C or 32 °F)."||13 °C
(post nuclear war)
|Jancovici, Jean-Marc. How do the present temperatures compare to the past ones? Jean-Marc Jancovici, 2004.||"It is remarkable that over the last 400.000 years, the maximum of the yearly average of the temperature exceeded the present values by just 1 to 2 °C (average temperature on earth was then 16 to 17 °C compared to 15 °C today) ; the last time that we reached such values was 130.000 years ago."||16–17 °C
The sun's visible light enters the earth's atmosphere in which infrared waves are reflected into the earth's ozone layer where it is trapped. When the sun's solar radiation passes through the clear atmosphere, the solar energy is absorbed by the earth's surface and warms it. Some solar radiation is reflected by the atmosphere and the earth's surface. But some of the infrared radiation is trapped by the greenhouse gas molecule like CO2 and methane. The direct effect is the warming of the earth's surface and the troposphere.
The effect of an increase in earth's average temperature will be expected to melt polar ice caps and glaciers in addition to warming the oceans. These changes will expand the ocean volume and raise sea level by an estimated 9 to 100 cm therefore flooding some coastal regions including entire islands.
The temperature change will also have an effect on soil, plants, and animals. The soil's dehydration can cause damaged food crops thus disrupting food supplies in parts of the world. Plants and animals species will shift their ranges toward the poles or to higher elevations seeking cooler temperatures.
As a result, many scientists have called for a worldwide cooperation and an immediate action to neutralize the problem.
Judy Tang -- 2005