Global Warming
What is Global Warming?
Global warmth begins with sunlight. When light from the Sun reaches the Earth, roughly 30 percent of it is reflected back into space by clouds, atmospheric particles, reflective ground surfaces, and even ocean surf. The remaining 70 percent of the light is absorbed by the land, air, and oceans, heating our planets surface and atmosphere and making life on Earth possible. Solar energy does not stay bound up in Earths environment forever. Instead, as the rocks, the air, and the sea warm, they emit thermal radiation, or infrared heat. Much of this thermal radiation travels directly out to space, allowing Earth to cool. Some of this outgoing radiation, however, is re-absorbed by water vapor, carbon dioxide, and other gases in the atmosphere (called greenhouse gases because of their heat-trapping capacity) and is then re-radiated back toward the Earths surface. On the whole, this re-absorption process is good. If there were no greenhouse gases or clouds in the atmosphere, the Earths average surface temperature would be a very chilly -18C (0F) instead of the comfortable 15C (59F) that it is today. What has scientists concerned now is that over the past 250 years humans have been artificially raising the concentration of greenhouse gases in the atmosphere at an ever-increasing rate. By 2004, humans were pumping out over 8 billion tons of carbon dioxide per year. Some of it was absorbed by sinks like forests or the ocean, and the rest accumulated in the atmosphere. We produce millions of pounds of methane by allowing our trash to decompose in landfills and by breeding large herds of methane-belching cattle. Nitrogen-based fertilizers and other soil management practices lead to the release of nitrous oxide into the atmosphere. Once these greenhouse gases get into the atmosphere, they stay there for decades or longer. According to the Intergovernmental Panel on Climate Change (IPCC), since the industrial revolution began in about 1750, carbon dioxide levels have increased 35 percent and methane levels have increased 148 percent. Paleoclimate readings taken from ice cores and fossil records show that these gases, two of the most abundant greenhouse gases, are at their highest levels in at least the past 650,000 years. Scientists have very high confidence (a phrase the IPCC translates to greater than 90 percent certainty) that the increased concentrations of greenhouse gases have made it more difficult for thermal radiation to leave the Earth, and as a result, Earth has warmed. Recent observations of warming support the theory that greenhouse gases are warming the world. Over the last century, the planet has experienced the largest increase in surface temperature in 1,300 years. The average surface temperature of the Earth rose 0.6 to 0.9 degrees Celsius (1.08F to 1.62F) between 1906 and 2006, and the rate of temperature increase nearly doubled in the last 50 years. Worldwide measurements of sea level show a rise of about 0.17 meters (0.56 feet) during the twentieth century. The worlds glaciers have steadily receded, and Arctic sea ice extent has steadily shrunk by 2.7 percent per decade since 1978. Even if greenhouse gas concentrations stabilized today, the planet would continue to warm by about 0.6C over the next century because it takes years for Earth to fully react to increases in greenhouse gases. As Earth has warmed, much of the excess energy has gone into heating the upper layers of the ocean. Scientists suspect that currents have transported some of this excess heat from surface waters down deep, removing it from the surface of our planet. Once the lower layers of the ocean have warmed, the excess heat in the upper layers will no longer be drawn down, and Earth will warm about 0.6C (1 F).
by: sunil kumar Homebuilding: Global Industry Guide Understanding Iso Shipping Standards Report On Global Lfp (lifepo4) Industry, 2009----aarkstore Enterprise Online Foreign Culture Learning Makes You Real Residents Of Global Village Oil & Gas: Global Industry Almanac Search Engine Marketing - Seo And Globalization Global And China's Li-ion Battery And Its Raw Materials Industry Report, 2008-2009 Chinas Continuing Development As A Global Trade Powerhouse Surprisingly Different Outlook For At&t And Verizon As They Deal With Bad Economy How are International Shipping Companies Useful Korean Technology Companies To Have A Major Impact On Global Smart Grid Market Global International packers and movers offers movers and packers, Car shifting services Essential Things To Know Before Purchasing A Macbook Case