Portal:Global warming

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Global warming

Instrumental Temperature Record
Glacier Mass Balance
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Global warming is the increase in the average temperature of the Earth's near-surface air and the oceans since the mid-twentieth century and its projected continuation. Global surface temperature increased 0.74 ± 0.18 °C (1.33 ± 0.32 °F) during the 100 years ending in 2005. The Intergovernmental Panel on Climate Change (IPCC) concludes that anthropogenic (human-sourced) greenhouse gases are responsible for most of the observed temperature increase since the middle of the twentieth century, and natural phenomena such as solar variation and volcanoes probably had a small warming effect from pre-industrial times to 1950 and a small cooling effect from 1950 onward. These basic conclusions have been endorsed by more than 40 scientific societies and academies of science, including all of the national academies of science of the major industrialized countries.

Climate model projections summarized in the latest IPCC report indicate that global surface temperature will probably rise a further 1.1 to 6.4 °C (2.0 to 11.5 °F) during the twenty-first century. The uncertainty in this estimate arises from the use of models with differing climate sensitivity, and the use of differing estimates of future greenhouse gas emissions. Some other uncertainties include how warming and related changes will vary from region to region around the globe. Although most studies focus on the period up to 2100, warming is expected to continue beyond 2100, even if emissions have stopped, because of the large heat capacity of the oceans and the lifespan of carbon dioxide in the atmosphere.

Pictured left: 1999-2008 Mean temperatures: This figure shows the difference in instrumentally determined surface temperatures between the period January 1999 through December 2008 and "normal" temperatures at the same locations, defined to be the average over the interval January 1940 to December 1980. The average increase on this graph is 0.48 °C, and the widespread temperature increases are considered to be an aspect of global warming. Source: NASA

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Glacier Mass Balance Map.png
Credit: Global Warming Art

The effective rate of change in glacier thickness, also known as the glaciological mass balance, is a measure of the average change in a glacier's thickness after correcting for changes in density associated with the compaction of snow and conversion to ice. The map shows the average annual rate of thinning since 1970 for the 173 glaciers that have been measured at least 5 times between 1970 and 2004. Larger changes are plotted as larger circles and towards the back.

All survey regions except Scandinavia show a net thinning. This widespread glacier retreat is generally regarded as a sign of global warming.

During this period, 83% of surveyed glaciers showed thinning with an average loss across all glaciers of 0.31 m/yr. The most rapidly growing glacier in the sample is Engabreen glacier in Norway with a thickening of 0.64 m/yr. The most rapidly shrinking was Ivory glacier in New Zealand which was thinning at 2.4 m/yr. Ivory glacier had totally disintegrated by circa 1988. [1]

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Turbine aalborg.jpg
Pictured left: Wind turbines near Aalborg, Denmark. Renewable energy projects are the most common source of carbon offsets.

A carbon offset is a reduction in emissions of carbon dioxide or greenhouse gases made in order to compensate for or to offset an emission made elsewhere.

Carbon offsets are measured in metric tons of carbon dioxide-equivalent (CO2e) and may represent six primary categories of greenhouse gases. The categories include: carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), perfluorocarbons (PFCs), hydroflourocarbons (HFCs), and sulfur hexaflouride (SF6). One carbon offset represents the reduction of one metric ton of carbon dioxide or its equivalent in other greenhouse gases.

There are two markets for carbon offsets. In the larger, compliance market, companies, governments, or other entities buy carbon offsets in order to comply with caps on the total amount of carbon dioxide they are allowed to emit. This market exists in order to achieve compliance with obligations of Annex 1 Parties under the Kyoto Protocol, and of liable entities under the EU Emissions Trading Scheme. In 2006, about $5.5 billion of carbon offsets were purchased in the compliance market, representing about 1.6 billion metric tons of CO2e reductions.

In the much smaller, voluntary market, individuals, companies, or governments purchase carbon offsets to mitigate their own greenhouse gas emissions from transportation, electricity use, and other sources. For example, an individual might purchase carbon offsets to compensate for the greenhouse gas emissions caused by personal air travel. Many companies offer carbon offsets as an up-sell during the sales process so that customers can mitigate the emissions related with their product or service purchase (such as offsetting emissions related to a vacation flight, car rental, hotel stay, consumer good, etc.). In 2008, about $705 million of carbon offsets were purchased in the voluntary market, representing about 123.4 million metric tons of CO2e reductions. See also green economics.

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Al gore presentation.jpg
Pictured left: Al Gore's speech on Global Warming at the University of Miami BankUnited Center, February 28, 2007.

Albert Arnold "Al" Gore, Jr. (born March 31, 1948) served as the 45th Vice President of the United States (1993–2001), under President Bill Clinton. He was the Democratic Party's nominee for President in the 2000 U.S. presidential election. Gore is currently an author and environmental activist. He has founded a number of non-profit organizations, including the Alliance for Climate Protection, and has received a Nobel Peace Prize for his work in climate change activism.

In his senior year at Harvard University, he took a class with oceanographer and global warming theorist Roger Revelle, who sparked Gore's interest in global warming and other environmental issues. After joining the U.S. House of Representatives, Gore held the first congressional hearings on the climate change, and co-sponsor[ed] hearings on toxic waste and global warming. Gore was known as one of the Atari Democrats, later called the "Democrats' Greens: politicians who see issues like clean air, clean water and global warming as the key to future victories for their party.

Gore wrote the book An Inconvenient Truth: The Planetary Emergency of Global Warming and What We Can Do About It, which won a Grammy Award for Best Spoken Word Album in 2009. An Inconvenient Truth is a 2006 documentary film directed by Davis Guggenheim about Al Gore's campaign to educate citizens about global warming via a comprehensive slide show that, by his own estimate, Gore has given more than a thousand times. Our Choice is a 2009 book written by Gore, originally titled, which followed the An Inconvenient Truth... (book). All profits of the book (printed on 100% recycled paper) go to the Alliance for Climate Protection, which Gore founded in 2006.

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Glaciercrevasse.jpg
Credit: North Cascade Glacier Climate Project

Measuring snowpack in a crevasse on the Easton Glacier, North Cascades, USA. The two-dimensional nature of the annual layers is apparent. Crucial to the survival of a glacier is its mass balance, the difference between accumulation and ablation (melting and sublimation). Climate change may cause variations in both temperature and snowfall, causing changes in mass balance.

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CasquetePolarSur.jpg
...that Mars' south polar ice cap may be melting due to global warming?

(Pictured left: Photo of Mars' south polar ice taken by Mars Global Surveyor.)

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