Global warming is the increase in the average measured temperature of the Earth's near-surface air and oceans since the mid-20th century, and its projected continuation.
1. What is the greenhouse effect, and is it affecting our climate?
The greenhouse effect is unquestionably real and helps to regulate the temperature of our planet. It is essential for life on Earth and is one of Earth's natural processes. It is the result of heat absorption by certain gases in the atmosphere (called greenhouse gases because they effectively 'trap' heat in the lower atmosphere) and re-radiation downward of some of that heat. Water vapour is the most abundant greenhouse gas, followed by carbon dioxide and other trace gases. Without a natural greenhouse effect, the temperature of the Earth would be about zero degrees F (-18°C) instead of its present 57°F (14°C). So, the concern is not with the fact that we have a greenhouse effect, but whether human activities are leading to an enhancement of the greenhouse effect by the emission of greenhouse gases through fossil fuel combustion and deforestation.
2. Are greenhouse gases increasing?
Human activity has been increasing the concentration of greenhouse gases in the atmosphere (mostly carbon dioxide from combustion of coal, oil, and gas; plus a few other trace gases). There is no scientific debate on this point. Pre-industrial levels of carbon dioxide (prior to the start of the Industrial Revolution) were about 280 parts per million by volume (ppmv), and current levels are greater than 380 ppmv and increasing at a rate of 1.9 ppm yr-1 since 2000. The global concentration of CO2 in our atmosphere today far exceeds the natural range over the last 650,000 years of 180 to 300 ppmv. According to the IPCC Special Report on Emission Scenarios (SRES), by the end of the 21st century, we could expect to see carbon dioxide concentrations of anywhere from 490 to 1260 ppm (75-350% above the pre-industrial concentration).
3. Is sea level rising?
Global mean sea level has been rising at an average rate of 1.7 mm/year (plus or minus 0.5mm) over the past 100 years, which is significantly larger than the rate averaged over the last several thousand years. Depending on which greenhouse gas increase scenario is used (high or low) projected sea-level rise is projected to be anywhere from 0.18 (low greenhouse gas increase) to 0.59 meters for the highest greenhouse gas increase scenario. However, this increase is due mainly to thermal expansion and contributions from melting alpine glaciers, and does not include any potential contributions from melting ice sheets in Greenland or Antarctica. Larger increases cannot be excluded but our current understanding of ice sheet dynamics renders uncertainties too large to be able to assess the likelihood of large-scale melting of these ice sheets.
Tuesday, October 7, 2008
Monday, October 6, 2008
Real Killers: Mankind
Anyone who really concerned about their living place must think of the thing which comes first in their mind after seeing this caption: Ya' Its Global Warming"
A Short Dialogue Between Earth And Mankind.
Earth: Hi, Humans U look so happy!
Mankind: Of course we're, Wit Our new technologies and inventions we can do anything to make us happy in this world.
Earth: But! How can u do without me?
Earth:"I'm Dying"
Mankind: Ha Ha!.. why do we think about U?
Earth: Sure You've to if I'm not there U'll not be;
Mankind: What do u mean?
Earth: Yeah! U Don't like me when I'm getting Angry(hotter).
Mankind: Wat made u to think so?
Earth: This thing Driven me to hell; The unawareness of wat humans doing to survive.
Still U Haven't realized wat you've done to me: I'm Transforming in other words.
Mankind: ?????
Earth: I'm Getting Hotter day by day cos of things U'r doing to survive in me. So Better try to stop transforming me and make Ur younger generations to have a place for living!!!!!
Stop Polluting The Earth And Save Our Planet:
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