Global warming skepticism

Proponents of Global warming assert some or all of the following, especially the first three:

global temperatures are rising,
the current warmth is unusual in the past 1000 years,
this warming is likely caused by human activity,
this warming could have serious consequences for mankind,
computer models correctly predict even greater warming,
action must be taken now to prevent warming.

Global warming skeptics maintain some or all of these assertions are not proven or not correct.

Note that within the global warming debate, the term "skeptic" has a particular meaning: it is the inverse of a proponent of global warming. The etymology of the term comes from scientific skepticism. However, all sides would claim to adhere to the the usual meaning of the term skeptic as "a scientific, or practical, position in which one does not accept the veracity of claims until solid evidence is produced".

Prominent skeptics

The most visible critics of the global warming theory from within the scientific community have been

Philip Abelson (deceased), former editor of Science
Patrick Michaels from the Department of Environmental Services at the University of Virginia
Robert Balling of Arizona State University
Sherwood B. Idso of the U.S. Water Conservation Laboratory [1]
S. Fred Singer, professor emeritus of environmental sciences at the University of Virginia
Richard Lindzen of Massachusetts Institute of Technology.
Ross McKitrick

Some prominent skeptics from outside the science community are:

John Daly (now deceased)
Andrei Illarionov, Russia's president Putin's economical policy advisor

Information Council on the Environment (ICE)

Michaels, Balling and Idso all lent their names in 1991 to the scientific advisory panel of the Information Council on the Environment (ICE), an energy industry public relations group.

Petitions and attacks on them

Global warming skeptics also dispute the claim (or relevance to reality) that a "growing consensus" of scientists support the global warming hypothesis, and that even the IPCC report authors do not all support the reports [2]. In fact, they say, the consensus of those who expend the effort to comment is moving in the opposite direction. To support this claim, the website of S. Fred Singer's Science and Environmental Policy Project (SEPP) lists four separate petitions:

The 1992 "Statement by Atmospheric Scientists on Greenhouse Warming" ("...Such policy initiatives [those concerning the Earth Summit is scheduled to convene in Brazil in June 1992] derive from highly uncertain scientific theories. They are based on the unsupported assumption that catastrophic global warming follows from the burning of fossil fuels and requires immediate action. We do not agree.") [3]
The "Heidelberg Appeal" (also from 1992)
Singer's own "Leipzig Declaration on Global Climate Change" (1995 and 1997)
The "Oregon Petition," which was circulated in 1998 by physicist Frederick Seitz.

According to SEPP associate Candace Crandall, these petititions show that "the number of scientists refuting global warming is growing."[4] However, people who have examinated the petitions challenge that conclusion, pointing out that:

The 1992 "Statement by Atmospheric Scientists" is more than a decade old and only has 46 signers.
The Heidelberg Appeal actually does not say anything about global warming.
Most of the signers of the Leipzig Declarations are non-scientists or lack credentials in the specific field of climate research.
Many of the signers of the Oregon Petition are also non-scientists or lack relevant scientific backgrounds.

Similar lists by supporters of global warming have received similar challenges.

In 1992 some 50 scientists signed a statement arguing that "[Global warming] policy initiatives derive from highly uncertain scientific theories. They are based on the unsupported assumption that catastrophic global warming follows from the burning of fossil fuels and requires immediate action. We do not agree." [5]

Global warming and carbon dioxide

One argument against global warming questions the contention that rising levels of carbon dioxide correlate with -- and thus have caused -- global warming.

Correlation is not causation. Indeed, studies of ice age temperature variations show carbon dioxide levels increasing after warming rather than before [6]. This however assumes that current climate change can be expected to be like past climate change. This in unlikely: past (ice age) variations are timed by astronomical forcing; the current variations, of whatever size, are timed by anthropogenic releases of CO2.
Most warming during the past century took place before most carbon dioxide had been released.

Global warming and solar activity

Another argument against man-made global warming (or anthropogenic global warming) is the discovery that changes in worldwide average temperature correlate closely with the intensity of solar radiation. The correlation between global temperature ups and downs, noted by "skeptics", is much closer than the claimed correlation between global temperature rise and carbon dioxide claimed by "warmers".

Global warming and the Kyoto Protocol

Skeptics, believing that carbon dioxide levels have no significant impact on global temperatures, feel that support for the Kyoto Protocol is entirely misguided.

Global Warming and future technology

Some skeptics believe that even if global warming is real and man-made, no action need be taken now because future scientific advances or engineering projects will remedy the problem before it becomes serious.

References

Committee on the Science of Climate Change, National Research Council, "Climate Change Science: An Analysis of Some Key Questions," (National Academies Press, 2001)

External links