GLOBAL WARMING Global warming is the rise in the average temperature of Earths atmosphere and oceans since the late 19th century and its projected continuation. Since the early 20th century, Earths mean surface temperature has increased by about 0.8 °C (1.4 °F), 2. Proposed policy responses to global warming include mitigation by emissions reduction, adaptation to its effects, and possible future geoengineering. Most countries are parties to the United Nations Framework Convention on Climate Change (UNFCCC), 3.Earths average surface temperature rose by 0.74±0.18 °C over the period 1906–2005. The rate of warming over the last half of that period was almost double that for the period as a whole (0.13±0.03 °C per decade, versus 0.07±0.02 °C per decade). The urban heat island effect is very small, estimated to account for less than 0.002 °C of warming per decade since 1900. 4. A climate model is a computerized representation of the five components of the climate system: Atmosphere, hydrosphere, cryosphere, land surface, and biosphere.[117] Such models are based on scientific disciplines such as fluid dynamics, thermodynamics as well as physical processes such as radiative transfer. The models take into account various components, such as local air movement, temperature, clouds, and other atmospheric properties; ocean temperature, salt content, and circulation; ice cover on land and sea; the transfer of heat and moisture from soil and vegetation to the atmosphere; chemical and biological processes; solar variability and others. Scientific discussion See also: Scientific opinion on climate change and Surveys of scientists views on climate change Most scientists agree that humans are contributing to observed climate change.[76][198] A meta study of academic papers concerning global warming, published between 1991 and 2011 and accessible from Web of Knowledge, found that among those whose abstracts expressed a position on the cause of global warming, 97.2% supported the consensus view that it is man made.[199] In an October 2011 paper published in the International Journal of Public Opinion Research, researchers from George Mason University analyzed the results of a survey of 489 American scientists working in academia, government, and industry. Of those surveyed, 97% agreed that that global temperatures have risen over the past century and 84% agreed that human-induced greenhouse warming is now occurring, only 5% disagreeing that human activity is a significant cause of global warming.[200][201] National science academies have called on world leaders for policies to cut global
Posted on: Thu, 07 Nov 2013 12:29:14 +0000
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