What is global warming? As defined by the Encarta Dictionary, this is an increase in global temperatures, believed to be partly caused by greenhouse gases. Holli Riebeek on the NASA Earth Observatory website describes it this way: “Global warming is the unusually rapid increase in the Earth's average surface temperature over the past century, primarily due to greenhouse gases.” It states that “surface temperatures have increased by an average of 0.6 to 0.9 degrees” over the past hundred years and that “the rate of temperature increase has nearly doubled over the past 50 years.” He goes a step further by boldly declaring that the gases are the direct result of “people burning fossil fuels” (Riebeek). Researchers, scientists, non-professionals, and I agree with Ms. Riebeek, man is the cause of global warming. The graph below shows the increase in Earth's temperature:Despite ups and downs from year to year, the global average surface temperature is increasing. At the beginning of the 21st century, Earth's temperature was about 0.5 degrees Celsius higher than the long-term average (1951-1980). (NASA figure adapted from Goddard Institute for Space Studies Surface Temperature Analysis.) Over the centuries, Earth has experienced climate change. History shows that warming and cooling trends have occurred, as the graph above clearly shows. According to NASA, climate change occurs “when the planet receives more or less sunlight due to subtle shifts in its orbit, when the atmosphere or surface changes, or when the sun's energy varies” (Riebeek). If climate modifications and changes in weather patterns occur naturally, then why are scientists and environmentalists in this situation during this time of global warming? It's not about warming... middle of paper... Change research project. March 12, 2011 .Marten, Gerald G. Human Ecology - Basic Concepts for Sustainable Development. Sterling, Virginia: Stylus Publishing, 2001. “Nitrogen Dioxide.” 17 July 2009. Ministry of the Environment. March 16, 2011 .Riebeek, Holli. "Earth Observatory". June 3, 2010. NASA. March 12, 2011 .Toomes, Ron. "Pollution." The best articles on global warming. March 25, 2011 .Vitousek, Peter M. “Beyond Global Warming: Ecology and Global Change.” Ecology 75.7 (1994): 1861-1876. Wolosz, Thomas. "Effects of Acid Rain". Plattsburg.edu. March 18 2011 .