Global Warming

Respected expert sources, such as the Intergovernmental Panel on Climate Change (IPCC), which was established jointly in 1988 by the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO), have concluded that the evidence for global warming is now unequivocal—there is no doubt it is occurring. Other reputable expert sources, such as the U.S. Environmental Protection Agency and the European Union, accept the scientific evidence that indicates that there has been an upward trend in the Earth's average surface temperature since the late 1800s. Global warming is relevant to the field of global studies given its implications for significant global climate change and the need for policy responses at an international scale.

The terms global warming and climate change are often used interchangeably in the popular media (if not in scientific journals), but they are not the same. Global warming refers to an overall [Page 751]warming of the Earth as measured by increasing average temperature near the Earth's surface and in the lowest layer of the atmosphere as a result of rising levels of greenhouse gases like carbon dioxide (CO2) and water vapor. Climate change refers to long-term change in the Earth's climate or in the climate of a region of the Earth. According to the National Academy of Sciences, the term climate change is increasingly preferred because it captures those other changes in global climate in addition to increasing temperature; so the term climate change includes not only global warming, but also other aspects of climate that rising greenhouse gas amounts affect, including major changes in rainfall, snow, humidity, and severe weather patterns that last for decades or longer.

Despite their bad reputation when it comes to global warming, greenhouse gases are essential for a livable planet. The greenhouse effect involves naturally occurring greenhouse gases that trap some of the heat from the sun in the Earth's lower atmosphere and prevent it from escaping back to space (similarly to how the glass walls of a greenhouse allow sunlight in but do not allow heat out). Without this natural occurrence, the Earth would be approximately 33°C (59°F) colder than otherwise and could not support human existence.

Many human activities result in greenhouse gases being released into the atmosphere, however, contributing to more global warming than that which naturally occurs. The additional greenhouse gases are created by burning fossil fuels like coal, natural gas, and oil to power factories, fuel vehicles, and heat and cool residential and commercial buildings. Other greenhouse gases come from forestry (including deforestation) and the agricultural sector. In addition to CO2 and water vapor, greenhouse gases include methane (CH4), nitrous oxide (N4O), hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride.

Scientific measurements indicate that greenhouse gases are currently rising at a more rapid rate than at any time during the last 650,000 years. The IPCC reports that global emissions of greenhouse gases from human activity have increased significantly since pre-industrial times, with an overall increase of 70% between 1970 and 2004. CO2 is the most important greenhouse gas in terms of human activity. The CO2 emissions—comprising 77% of total greenhouse gases from human activity in 2004—increased by approximately 80% between 1970 and 2004. The rate of CO2 increase during the 10-year period 1995 to 2004 has also been much higher than during the period 1970 to 1994. These increased greenhouse gases, which are primarily from human activities, are associated with increased global temperatures.

...