Amongst some sections of the scientific community, controversy continues to surround the hypothesis that human activities are contributing significantly to global warming. The IPCC science working group agrees that there are significant successes and problems with the simulations which are used to predict climate, while opponents assert that the summaries omit the negative aspects (see IPCC) and mostly report progress is being made in understanding climate. A number of scientists with backgrounds in climate research -- notably Richard Lindzen, Fred Singer, Patrick Michaels, Robert Balling and Sherwood Idso -- dispute the global warming theory (see global warming skepticism). Also, a number of conservative think tanks oppose the theory, some implying that fraud has been involved in advocacy for it (see Science and Environmental Policy Project).
Support of industry-backed organizations (such as the Global Climate Coalition, the Greening Earth Society for these scientists' skepticism is taken by some as evidence against their contention that the theory is unproven. If the fossil-fuel industry is assumed to always value profit above scientific rigor, then the integrity of any scientist funded by that industry is assumed to be compromised, especially if that scientist's views are favorable to the continued health of fossil-fuel industry. Some critics of environmentalist politics see this argument as an indirect ad hominem attack on the scientists mentioned above.
A degree of uncertainty remains. Some believe that the present warming trend shown by some land-based weather stations, marine observations, borehole thermometry, and satellite observations is likely to continue or increase, fueled by the emission of carbon dioxide and other gases which are believed to be "greenhouse gases". Others argue that solar variability plays a much bigger role in climate change and question whether the human influence is even discernible.
Uncertainty also remains about the likely magnitude of future global warming (the IPCC suggests a range of 1.4 to 5.8 °C between 1990 and 2100 [1]) and its environmental impacts. Environmentalists and other advocates fear that the impacts will be profound. If warming were to continue at the present rate, there would be adverse changes in ocean circulation, catastrophic global climate change, loss of biodiversity and irreversible damage to agriculture in those ecoregions most affected. In some regions, e.g. Western Europe and Bangladesh, damage is projected to be extreme, due to loss of Gulf Stream warming and global sea level rise respectively. More frequent bouts of destructive weather are also anticipated, and risk experts in the insurance industry have expressed very strong concerns, advocating a proactive approach based on the precautionary principle. Estimates accepted by the IPCC and by some insurance industry bodies estimate up to 3.5 billion people could be affected by rising disease, loss of fresh water supply, and other impacts.
In opposition stand the fossil fuel industry and its advocates, who have taken a strong stand in opposing most theories of human-caused global warming as well as action to mitigate Global Warming. They argue that crippling the energy industry to prevent an ecological catastrophe does not make economic sense - that healthy economies are required to fund technologically innovative solutions. US president George W. Bush made this argument in rejecting the Kyoto Protocol. Bush did not reject the science outright, but argued that the greenhouse gas control was a matter of voluntary restraint by industry. However, many countries have rejected these arguments and have signed up to the Kyoto Protocol. Also, many U.S. states have nonetheless put strong controls on greenhouse gases.
This standoff has made the scientific questions difficult to distinguish from political ones.
The proportion of scientists who support or oppose any of the global warming theories is a matter of controversy in its own right (see scientific opinion of global warming). Environmentalists and their allies claim virtually unanimous support for the global warming theory from the scientific community. Opponents maintain that it is the other way around, claiming that the overwhelming majority of scientists either dismiss global warming altogether or merely consider it "unproven" (see global warming skepticism).
The arguments over global warming are viewed differently in different parts of the world. In Europe for example the environmentalist argument over Global warming has gained wider acceptance than in other parts of the world, most notably North America.
Other researchers feel that up to 1.5 degrees Centrigade of warming would increase crop yields and stabilize weather. Many of these doubt a larger warming is likely. In response, some advocates of strong early measures (well beyond Kyoto) note that the belief in beneficial effects and the doubt that a large warming is possible should be independent if these conclusions were in fact neutrally derived from scientific research.
New findings have suggested that the earth's climate system is inherently unstable, and that global warming could thus precipitate non-linear sudden climate shifts, as have been discovered to have occurred within the earth's past. Ocean circulation, believed to be the key to such climate shifts, has been observed to be slowing, causing alarm among oceanographers.
As briefly mentioned before some scientists fear that the Gulf stream which conveys warm water from the Caribbean Sea across the Atlantic Ocean and is partly responsible for the relative mildness of northern Europe's climate (though other factors also predominate: [1]). There is a fear that it could be reduced or stopped altogether by the decreased salt content in the sea water, which would result from global warming. Which could cause temperatures in northern europe to drop.
The US National Academy of Sciences issued a report on this phenomenon in 2002, titled Abrupt Climate Change - Inevitable Surprises.[1] "It is important not to be fatalistic about the threats posed by abrupt climate change," it stated. "Societies have faced both gradual and abrupt climate changes for millennia and have learned to adapt through various mechanisms, such as moving indoors, developing irrigation for crops, and migrating away from inhospitable regions. Nevertheless, because climate change will likely continue in the coming decades, denying the likelihood or downplaying the relevance of past abrupt events could be costly."
Advocates of the global warming hypothesis who predict adverse consequences from as little as 1.5 degrees Centigrade of warming nearly all support the Kyoto Protocol as a countermeasure. Details of the agreement are in the article about the Kyoto Protocol, including both the pollution and fiscal requirements.
Controversy in scientific community
Uncertainty
Magnitude of warming
Opposition
Standoff
Counting experts
Arguments around the world
Cause or effect
Some scientists point out that global warming correlates closely with natural factors, especially solar activity. The balance is attributed to the action of humans (see anthropogenic global warming). How much warming is natural versus man-made has been debated since the 1990s by scientists, politicians and advocacy organizations.Beneficial or detrimental
There is also disagreement on whether the effects of global warming will be beneficial or detrimental. Many researchers predict disastrous consequences for a warming of 1.5 to 7 degrees celsius. The UN's Intergovernmental Panel on Climate Change (IPCC) predicts such a warming is likely within the 21st century, unless severe measures are taken (see Kyoto Protocol). Wait and see
Others suggest that a "wait and see" strategy disadvantages 3.5 billion people in favor of narrow advantage for a few growing regions and developed nations. An unstable world
Historical temperature record
There is also disagreement on the historical temperature record. Depending on what direct measurements and measurement proxies are used, researchers have presented various derived historical temperature records. One popular study suggests stable temperature followed by a sudden, steady rise in the 20th century. Numerous studies indicate a cold period called the Little Ice Age which ended just before the 20th Century. Recent actual temperature records indicate rising temperatures during the 20th Century until 1945, then a thirty year period of cooling until warming again since 1976.Recent reports
However, the US National Academy of Sciences, both in its 2002 report to President George W. Bush, and in its latest publications, has strongly endorsed evidence of an average global temperature increase in the 20th century and stated that human activity is heavily implicated in causing this increase.
The American Meteorological Society (AMS statement), the American Geophysical Union (AGU statement), and other scientific societies have issued similar declarations.Proponents' Position
Supporters of the global warming hypothesis portray the controversy as a conflict between unbiased scientists warning the public against the danger of global warming and greedy, unscrupulous energy companies distorting the facts for the sake of profit. The motivation of proponent organizations is often ignored.Skeptics' Position
Members of this faction give more weight to data such as temperature measurements made from weather balloons and satellites which they claim show less warming than surface land and sea records.