Until recently, researchers were uncertain whether Climate developments reflected natural variations in the Earth, or whether in fact human activities contributed to the warming. The latest observed data reveals some striking trends: - All 10 of the warmest years on record have occurred in the last 15 years. - The 1990s have already been warmer than the 1980s - the warmest decade on record - by almost 0.2°F (0.1°C), according to the Goddard Institute of Space Studies. - The global average surface temperature has risen 0.5°-1.1°F (0.3°-0.6°C) since reliable records began in the second half of the 19th century. In 1995, scientists with the Intergovernmental Panel on Climate Change - the authoritative international body charged with studying this issue-reached a conclusion in the Second Assessment Report, which summarizes the current state of scientific knowledge on global warming, also called climate change. For the first time ever, the Panel concluded that the observed increase in global average temperature over the last century "is unlikely to be entirely natural in origin" and that "the balance of evidence suggests that there is a discernible human influence on global climate."
The Earth's climate is the result of extremely complex interactions among the atmosphere, the oceans, the land masses, and living organisms, which are all warmed daily by the sun's energy. This heat would radiate back into space if not for the atmosphere, which relies on a delicate balance of heat-trapping gases - including water vapor, carbon dioxide, nitrous oxide, and methane - to act as a natural "greenhouse," keeping in just the right amount of the sun's energy to support life. For the past 150 years, though, the atmospheric concentrations of these gases, particularly carbon dioxide, have been rising. As a result, more heat is being trapped than previously, which in turn is causing the global temperature to rise. Climate scientists have linked the increased levels of heat-trapping gases in the atmosphere to human activities, in particular the burning of fossil fuels (coal, oil, and natural gas for heating and electricity; gasoline for transportation), deforestation, cattle ranching, and rice farming. But Global Warming has received much press in the past decade. There are many questions like these ones. Could the earth’s climate really heat up? What are the causes if such a warming occurs? Is global warming a theory and thrue or false theory at that? These questions and more are what climate scientists are asking themselves daily. So, there are two sides to every story and both are discussed in the media.
As the Earth's climate is the result of extremely complex interactions, scientists still cannot predict the exact impact on the earth's climate of these rising levels of heat-trapping gases over the next century. But there is striking agreement among most climate scientists about what is likely to occur. Poureful climate models suggest that the planet will warm over the next century at a more rapid rate than ever before recorded. The current best estimate is that if carbon dioxide concentrations double over preindustrial levels, global average surface temperatures will rise between 1.8° and 6.3°F (between 1° and 3.5°C). According to the scientific possible scenarios, an atmospheric doubling of carbon dioxide could occur as early as 2050. Future impacts from this kind of warming will most likely include: - damage to human health - severe stress on forests, wetlands, and other natural habitats - dislocation of agriculture and commerce - expansion of the earth's deserts - melting of polar ice caps and consequent rise in the sea level - more extreme weather events
The Future and Global Warming Policy
During the 1980-90s, evidence mounted that increased atmospheric concentrations of heat-trapping gases could cause significant disruptions of the earth's climate systems. These discoveries moved the global warming issue into the arena of public policy
Реферат опубликован: 11/04/2010