Global warming exists and it is man made.

The greenhouse effect: The phenomenon whereby the earth's atmosphere traps solar radiation, caused by the presence in the atmosphere of gases such as carbon dioxide, water vapor, and methane that allow incoming sunlight to pass through but absorb heat radiated back from the earth's Greenhouse gases: Any of the atmospheric gases that contribute to the greenhouse effect by absorbing infrared radiation produced by solar warming of the Earth's surface. They include carbon dioxide (CO2), methane (CH4), nitrous oxide (NO2), and water vapor. Although greenhouse gases occur naturally in the atmosphere, the elevated levels especially of carbon dioxide and methane that have been observed in recent decades are directly related, at least in part, to human activities such as the burning of fossil fuels and the deforestation of tropical forests. The sun constantly bathes the earth in all types of radiation. Usually this is just radiated back into space but when there are large concentrations of greenhouse gases interact with this radiation and turn it to heat and trap it whereas other non greenhouse gases do not interact with it. Indicators that the earth is warming include the following: (1) CO2 concentration in the atmosphere is at it's highest in over 400,000 years. We already know that CO2 is a greenhouse gas which traps heat. In the past CO2 concentration has fluctuated. However it has never reached past 300ppm(parts per million). The fluctuations can generally be attributed to volcanic eruptions which release large amounts of CO2 into the air. However, in the past 60 years there has been a dramatic increase in CO2 concentration. It ha risen to a 400,000 year high of over 380ppm. This can be attributed to the recent drastic increases in deforestation and burning of fossil fuels. Both of these activities release large amounts of CO2 into the air. It is highly unlikely that there was a random CO2 spike(the highest in almost half a million years) just as humans began to dramatically increase levels of deforestation and burning of fossil fuels. From these facts we can connect the CO2 rise to human activities (2) The global surface temperature has been steadily rising. 2000 to 2009 was the warmest decade since as far as back a we have measured the global surface temperature. This is consistent with the fact that large concentrations of CO2 turn infrared radiation to heat and trap it in the earth's atmosphere while non greenhouse gases do not interact with infrared radiation. Similar reconstructions have been produced by the Climatic Research Unit and the National Atmospheric and Oceanic Administration. I have here cited a reconstruction by NASA. http://climate.nasa.gov... (3) The levels of Artic sea ice have fallen visibly in recent years. The levels of Artic sea ice have fallen from over 7 million sq. miles to just under 5 million sq. miles. This is consistent with rising global temperatures as a result of rising CO2 concentration in the atmosphere as a result of rapid increases in CO2 producing activities such as deforestation and burning of fossil fuels. This shows that not only is the earth becoming warmer but that it is almost entirely man made.