Thursday, October 18, 2007

Some definitions


Global warming refers to the increase in the
average temperature
of the Earth's near-surface air and oceans in recent decades and its projected continuation.

The global average air temperature near the Earth's surface rose 0.74 ±/wiki/Plus-minus_sign 0.18 EC (1.33 ± 0.32 EF) during the last 100 years. The Intergovernmental Panel on Climate Change (IPCC) concludes, "most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations"[1] via the greenhouse effect.

Natural phenomena such as solar variation combined with volcanoes probably had a small warming effect from pre-industrial times to 1950 and a small cooling effect from 1950 onward.[2][3] These basic conclusions have been endorsed by at least 30 scientific societies and academies of science, including all of the national academies of science of the major industrialized countries.
However, a few individual scientists disagree with some of the main conclusions of the IPCC.

The Intergovernmental Panel on Climate Change (IPCC) was established in 1988 by two United Nations organizations, the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP), to evaluate the risk of climate change caused by human activity.

The IPCC shared the 2007 Nobel Peace Prize with former Vice President of the United States Al Gore [1].

The IPCC does not carry out research, nor does it monitor climate or related phenomena. One of the main activities of the IPCC is to publish special reports on topics relevant to the implementation of the UN Framework Convention on Climate Change (UNFCCC).[2] (The UNFCCC is an international treaty that acknowledges the possibility of harmful climate change; implementation of the UNFCCC led eventually to the Kyoto Protocol.)

The IPCC bases its assessment mainly on peer reviewed and published scientific literature. [3] The IPCC is only open to member states of the WMO and UNEP. IPCC reports are widely cited in almost any debate related to climate change.[4][5] National and international responses to climate change generally regard the UN climate panel as authoritative.[6]

All IPCC technical reports face extensive scientific review. The summary reports (i.e. Summary for Policymakers), which draw the most media attention, include review by participating governments in addition to scientific review.[7]


The Working Group I Summary for Policymakers (SPM) was published on
2007[12] and revised on 5 February 2007[13]. There was also a 2 February 2007 press release[14]. The full WGI report[15] was published in March. The key conclusions of the SPM were that[16]:

Warming of the climate system is unequivocal.

Most of (>50% of) the observed increase in globally averaged temperatures since the mid-20th century is very likely (confidence level >90%) due to the observed increase in anthropogenic (human) greenhouse gas concentrations.

Hotter temperatures and rises in sea level "would continue for centuries" even if greenhouse gas levels are stabilized[17], although the likely amount of temperature and sea level rise varies greatly depending on the fossil intensity of human activity during the next century (pages 13 and 18)[13].

The probability that this is caused by natural climatic processes alone is less than 5%.
World temperatures could rise by between 1.1 and 6.4 EC (2.0 and 11.5 EF) during the 21st century (table 3) and that:

Sea levels will probably rise by 18 to 59 cm (7.08 to 23.22 in) [table 3].

There is a confidence level >90% that there will be more frequent warm spells, heat waves and heavy rainfall.

There is a confidence level >66% that there will be an increase in droughts, tropical cyclones and extreme high tides.

Both past and future anthropogenic carbon dioxide emissions will continue to contribute to warming and sea level rise for more than a millennium.

Global atmospheric concentrations of carbon dioxide, methane, and nitrous oxide have increased markedly as a result of human activities since 1750 and now far exceed pre-industrial values over the past 650,000 years

An outline of chapters in the WGI report (as of November 3, 2005)[18] and a list of the report's authors (as of March 10, 2005)[19] were made available before publication of the SPM.
The Summary for Policymakers for the Working Group II [1] report was released on April 6, 2007[20]. The Summary for Policymakers for the Working Group III report [21] was released on May 4, 2007. The AR4 Synthesis Report (SYR) will be released in November 2007.

More to come.

Terry Bankert

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