Portal:Global warming

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Global mean surface-temperature change from 1880 to 2017, relative to the 1951–1980 mean. The black line is the global annual mean, and the red line is the five-year local regression line. The blue uncertainty bars show a 95% confidence interval.

Global warming, also referred to as climate change, is the observed century-scale rise in the average temperature of the Earth's climate system and its related effects. Multiple lines of scientific evidence show that the climate system is warming. Many of the observed changes since the 1950s are unprecedented in the instrumental temperature record, which extends back to the mid-19th century, and in paleoclimate proxy records of climate change over thousands of years. The phenomenon is sometimes called "anthropogenic global warming" or "anthropogenic climate change" in view of the dominant role of human activity as its cause.

In 2013, the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report concluded, "It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century." The largest human influence has been the emission of greenhouse gases such as carbon dioxide, methane, and nitrous oxide. Climate model projections summarized in the report indicated that during the 21st century, the global surface temperature is likely to rise a further 0.3 to 1.7 °C (0.5 to 3.1 °F) in the lowest emissions scenario, and 2.6 to 4.8 °C (4.7 to 8.6 °F) in the highest emissions scenario. These findings have been recognized by the national science academies of the major industrialized nations and are not disputed by any scientific body of national or international standing.

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Arctic sea ice loss animation.gif
Credit: NASA

This time series, based on satellite data, shows the annual Arctic sea ice minimum since 1979. The September 2010 extent was the third lowest in the satellite record.

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Mirandela frost 2.JPG
The Great Freeze refers to the winter of 1894-1895, especially in Florida where the brutally cold weather destroyed much of the nation's citrus crop.

There were actually twin freezes in Florida during this momentous season, the first in December 1894 and the second in February 1895. The first did not actually kill a lot of groves, but did cause them to produce new shoots. So, when the second, harder freeze came a few months later, the effects were even more devastating. All varieties of fruit (oranges, grapefruits, lemons, limes, etc.) blackened on the trees, and bark split from top to bottom. These effects were felt as far south as the Manatee River, below Tampa.

Up to 1895, the cheap abundance of semi-tropical citrus groves extended into northern Florida and were producing as much as 6 million boxes of fruit per year. After the Great Freeze, however, production plummeted to just 100,000 boxes and did not break the 1 million mark again until 1901. As a result, land values also dropped in the citrus growing areas from $1,000 per acre to as little as $10 per acre. Many compared the economic impact of the Great Freeze on Florida to the effects of the Great Fire on the city of Chicago.

In the wake of the Great Freeze, many planters simply abandoned their Florida groves in search of frost-free locations in places as far away as Cuba, Puerto Rico, and Jamaica. Others relocated to California, utilizing a seedless variety of grapefruit discovered by C.M. Marsh near Lakeland, Florida. Growers who were not able to abandon the region were forced to try their hands at growing other crops, which had the positive result of diversifying Florida's agriculture. For instance, Palatka became particularly well-known for its potato crop in the years following the Great Freeze; and Sanford was closely identified with celery.

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Jean Baptiste Joseph Fourier (March 21, 1768 – May 16, 1830) was a French mathematician and physicist best known for initiating the investigation of Fourier series and their application to problems of heat flow. The Fourier transform is also named in his honour. Fourier is also generally credited with the discovery of the greenhouse effect.

Fourier was born at Auxerre (in east-central France), the son of a tailor. He was orphaned at age nine. Fourier was recommended to the Bishop of Auxerre, and through this introduction, he was educated by the Benvenistes of the Convent of St. Mark. The commissions in the scientific corps of the army were reserved for those of good birth, and being thus ineligible, he accepted a military lectureship on mathematics. He took a prominent part in his own district in promoting the French Revolution, and was rewarded by an appointment in 1795 in the École Normale Supérieure, and subsequently by a chair at the École Polytechnique.

In 1822 Fourier presented his work on heat flow in Théorie analytique de la chaleur (The Analytic Theory of heat), in which he based his reasoning on Newton's law of cooling, namely, that the flow of heat between two adjacent molecules is proportional to the extremely small difference of their temperatures. A significant contribution was Fourier's proposal of his partial differential equation for conductive diffusion of heat. This equation is now taught to every student of mathematical physics.




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Space lens.png

The basic function of a space sunshade to mitigate global warming. A 1000 kilometre diameter lens is sufficient, and much smaller than what is shown in this simplified image. As a Fresnel lens it would be only a few millimeters thick.

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...that global warming of the average air temperature rose 0.74 ± 0.18 °C (1.3 ± 0.32 °F) during the past century?

(Pictured left: Animated global map of monthly long term mean surface air temperature (Mollweide projection))

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