Global Warming Issue | A Presentation in English
Global Warming Issue | A Presentation in English
LELB Lecturer: Sasan
Selected text about global warming
Global warming is the gradual heating of Earth’s surface, oceans and atmosphere. Scientists have documented the rise in average temperatures worldwide since the late 1800s. Earth’s average temperature has risen by 1.4 degrees Fahrenheit (0.8 degrees Celsius) over the past century, according to the Environmental Protection Agency (EPA). Temperatures are projected to rise another 2 to 11.5 degrees F (1.133 to 6.42 degrees C) over the next 100 years.
Most of the leading scientific organizations in the world acknowledge the existence of global warming as fact, according to a NASA report. Furthermore, 97 percent of climate scientists agree that the rate of global warming trends the planet is now experiencing is not a natural occurrence, but is primarily the result of human activity. That consensus was made clear in a major climate report released Sept. 27, 2013, by the Intergovernmental Panel on Climate Change (IPCC). In that report, climate scientists indicated they are more certain than ever of the link between human activities and global warming.
The greenhouse effect
Global warming begins with the greenhouse effect, which is caused by the interaction between Earth’s atmosphere and incoming radiation from the sun. “The basic physics of the greenhouse effect were figured out more than a hundred years ago by a smart guy using only pencil and paper (Svante Arrhenius in 1896),” Josef Werne, an associate professor in the department of geology and planetary science at the University of Pittsburgh, told Live Science.
Solar radiation passes through the atmosphere to the surface of Earth, where it is absorbed and then radiated upward as heat. Gases in Earth’s atmosphere absorb about 90 percent of this heat and radiate it back to the surface, which is warmed to a life-supporting average of 59 F (15 C). This very helpful process is called the greenhouse effect.
