1、WELCOME TO MY SPEECH,The Greenhouse Effect,“Venus is too hot, Mars is too cold, and Earth is just right.“ The fact that Earth has an average surface temperature comfortably between the boiling point and freezing point of water, and thus is suitable for our sort of life, cannot be explained by simply
2、 suggesting that our planet orbits at just the right distance from the sun to absorb just the right amount of solar radiation. Our moderate temperatures are also the result of having just the right kind of atmosphere,The earths “greenhouse effect“ is what makes this planet suitable for life as we kn
3、ow it. The earths atmosphere contains trace gases, some of which absorb heat. These gases (water vapor, carbon dioxide, methane, ozone, and nitrous oxide) are referred to as “greenhouse gases.“ Albedo has an important influence on the earths temperature. Greenhouses are structures designed to retain
4、 heat. The heat-trapping ability of a greenhouse is influenced by a number of factors including the transparency of the greenhouse cover, color of the surfaces inside the greenhouse, and type of surfaces inside.,A worldwide greenhouse effect might produce a dangerously warmer world. Since the late 1
5、9th century, the average global temperature has increased between 0.54 F and 1.08 F (0.3 C and 0.6 C). Internationally, 1990 was the hottest year on record since official weather records first started being kept by the British in about 1860. Estimates of global average temperatures have projected an
6、 increase of as much as 9 F(5 C) before the year 2100.,The effects of global warming are most obviously the warming of the globe, but this can have many unforeseen side effects, such as the melting of some of the earths ice stored in its poles and its glaciers, such as the Greenland Ice Sheet, a ris
7、e of three to four degrees Fahrenheit could cause up to 40 per cent of the earths costal areas to be enveloped by the rising oceans. The global temperature has risen between 0.45 to 0.6 degrees Celsius and the oceans have risen between 15-20 cm in the last century due to global warming and the indus
8、trial revolution.,Less snow in summer. Summer days without snow have increased from fewer than 80 in the 1950s to more than 100 in the 1990s. Photo: Scientists record ground data to confirm NDVI readings in Alaska. Antarctic Peninsula Since 1945, the Antarctic Peninsula has experienced a warming of
9、about 4.5?F (2.5?C). The annual melt season has increased by 2 to 3 weeks in just the past 20 years.,Sea bird population decline. The black guillemot population is declining from 1990 levels because melting sea ice has increased the distance the birds must fly to forage for food and reduced the number of resting sites available. Penguin population decline. Adelie Penguin populations have shrunk by 33 percent during the past 25 years in response to declines in their winter sea ice habitat Photo: Dr. Bill Fraser surveying an Adelie Penguin population,WHAT CAN WE DO,Thank you,
