Global warming is the observed century scale rise in the average temperature of the Earth's climate system and its related effects as part of climate change. Earth's climate changed many times. Our planet has gone through multiple ice ages, in which ice sheet and glaciers covered large portions of the Earth. It has also gone through warm periods when temperatures were higher than they are today. Past change of the Earth's temperature happened very slowly, over hundred of thousand of years. However, the recent warming trend is happening much faster than in the past. Natural cycle like cooling and warming are not enough to determine the average scale of the warming period that people experienced in a short time.
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According to some researchers, the Earth's average temperature have risen about 0.74 degree celsius ( 1.33 degree Fahrenheit ) during the past 100 years. The increase happening in northern latitudes. Scientist state that most of the current temperature increasing since the mid-20 century are due to human activities. Human activities contribute to global warming by also increasing the greenhouse effect. Some certain gases collects from the Earth's atmostphere in naturally include carbon dioxide, methane, nitrogen oxide, and fluorine gases. The type of gases mostly causes by human are carbon dioxide that people put into the atmosphere come from burning fossils fuels. Many electric power plants also burn fossils fuel.
Another ways that human release carbon dioxide into the atmosphere is by cutting down the forest tree. First, this happen because of the two main reasons. They decayed plant material, release tons of carbon into the atmosphere. Living trees absorb carbon dioxide. People diminishing the trees to absorb the carbon then the gases still remaining in the atmosphere. Second, most methane in the atmosphere comes from livestock farming, landfills, and other productions are known for coal mining and natural gas processing. Nitrous oxide often come from agriculture technology that burning the fossil fuels. Third, one kind of gas called fluorinated gas include carbon, chlorine, and hydro combination to forming the gas.
As a result of human activities, people adding more greenhouse gases to the atmosphere that causing more heat than usual and contributing to global warming.
Scientist uses drill cores through the Earth's polar ice sheets. They uses that to find out the temperature of the Earth's atmosphere in the past so that they can predict how the climate change in the future of the next several decades. They have to concentrating of greenhouse gases since the industrial revolution are higher than they've been for hundreds of thousands of years.
The models help scientists to understand the Earth's climate, or long-term weather patterns. Models also allow scientists to make predictions about the future climate. Basically, models simulate how the atmosphere and oceans absorb energy from the sun and transport it around the globe. Factors that affect the amount of the sun's energy reaching Earth's surface are what drive the climate in these models, as in real life.
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