A trend in the physical environment of the planet, sometimes imprecisely called global warming because an increase in average global temperatures that has been observed in recent decades is part of the process. Global climates have changed many times during the earth's long history, under the influence of variations in solar flare activity, the precession of the earth's axis, the impedance of solar radiation by atmospheric dust such as that emitted by massive volcanic eruptions, tectonic plate movement that modifies the direction and force of ocean currents, and other natural processes. The Intergovernmental Panel on Climate Change (IPCC) has been studying the phenomenon since 1985. In its reports in 1995 and 2001, it stated that the current trends can be partly attributed to the effects of human activity, especially to the increase in atmospheric burden of greenhouse gases produced by combustion of carbon-based fuels that permit solar energy to reach the earth's surface but block the escape back to space of radiation reflected from the earth's surface. The main effects, in addition to a long-term warming trend, include increased frequency of climatic extremes and violent weather events, sea level rise, and a range of adverse health effects that include harm due to heat waves and smog, increased frequency of vector-borne diseases, and displacement of populations because of habitat loss. See http://www.ipcc.ch for details.
Subjects: Public Health and Epidemiology.