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The global warming controversy is a long-running dispute about human effects - past, present and future - on climate. The starting point is whether there has been significant global warming caused by industrial emissions of carbon dioxide. But this alone would be a scientific argument confined to the scientific press. The point that leads to major controversy - because it could have significant economic impacts - is whether action (usually, restrictions on the use of fossil fuels to reduce CO2 emissions) should be taken now or in the near future.The science of global warming is spread over several articles:
1 Scope of the controversy
The controversy occurs almost entirely within the press and political arenas. In the scientific press and amongst climate researchers, there is little "controversy" about global warming, only a desire to investigate a scientific problem and determine its consequences. As Kevin E. Trenberth writes:
- In 1995 the IPCC assessment concluded that "the balance of evidence suggests that there is a discernible human influence on global climate". Since then the evidence has become much stronger ... Thus the headline in IPCC (2001) is "There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities"... While some changes arising from global warming are benign or even beneficial, the economic effects of the weather extremes are substantial and clearly warrant attention in policy debates... Consequently, there is a strong case for slowing down the projected rates of climate change from human influences. [1]
Trenberth also provides evidence for the controversy that occurs when science meets the political arene:
- The SPM was approved line by line by governments... The argument here is that the scientists determine what can said, but the governments determine how it can best be said. Negotiations occur over wording to ensure accuracy, balance, clarity of message, and relevance to understanding and policy. The IPCC process is dependent on the good will of the participants in producing a balanced assessment. However, in Shanghai, it appeared that there were attempts to blunt, and perhaps obfuscate, the messages in the report, most notably by Saudi Arabia. This led to very protracted debates over wording on even bland and what should be uncontroversial text... The most contentious paragraph in the IPCC (2001) SPM was the concluding one on attribution. After much debate the following was carefully crafted: "In the light of new evidence, and taking into account the remaining uncertainties, most of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations."[2]
The arguments over global warming are viewed differently in different parts of the world. In Europe for example global warming has gained wider acceptance than in other parts of the world, most notably North America.
2 Points made by supporters of the Global Warming theory
Supporters of the global warming theory assert that:
- the historical temperature record shows a rise of 0.4-0.8 °C over the last 100 years
- the current warmth is unusual in the past 1000 years (see Temperature record of the past 1000 years)
- the warming of the last 50 years is likely caused by human activity (see attribution of recent climate change)
- humankind is performing a great geophysical experiment and if it turns out badly - however that is defined - we cannot undo it.
- climate models can reproduce this trend, but only when using greenhouse gas forcing [3]
- climate models predict more warming, and other climate effects ( sea level rise, etc) in the future
- action should be taken now to prevent or retard warming (see Precautionary principleThe precautionary principle a phrase coined circa 1988, is the ethical principle that if the consequences of an action, especially the use of technology, are unknown but are judged by some scientists to have a high risk of being negative from an ethical p)
- the IPCC reports correctly summarise the state of climate science
- there is a scientific consensus behind all of the above
Opponents of GWT maintain some or all of these assertions are not proven or not correct.
Proponents of global warming tend to support the IPCC position and thus represent a broadly unified viewpoint, though with considerable differences over what action should be taken. Optionally, supporters may go on to point out that there is a good chance that the future changes may be undesirable, and that planning to avoid or mitigate them would be a good idea.
Participation in the IPCC process does not imply endorsement of it. However, only 2 of the 120 contributing authors to the IPCC TARTAR can mean: An abbreviation for Tar file format The Amazing Race a reality television program An abbreviation for Tibet Autonomous Region The Third Assessment Report of the IPCC TLAs. are known to have voiced any complaint.
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![[3]](http://www.cgd.ucar.edu/cas/GLOB_CHANGE/ipcc2001_figs/fig3.gif){kind=link}