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Context of 'June 22, 2006: Second Study Concludes that Climate is Warmer Now Than Any Other Period in Last 400 Years'

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Nature publishes a study by climate scientists Raymond Bradley, Michael Mann, and Malcolm Hughes concluding that the last few decades were warmer than any comparable time period in the last 1,000 years. Their study shows that the pace of warming was most dramatic during the last century. The authors identified the increase of greenhouse gases in the atmosphere as the dominant factor in the observed increase in global temperatures. [Nature, 4/23/1998 pdf file; San Francisco Chronicle, 6/23/2006]

Entity Tags: Malcolm Hughes, Raymond Bradley, Michael Mann

Timeline Tags: Global Warming

The Intergovernmental Panel on Climate Change (IPCC) releases its third assessment report on global warming, concluding that the planet’s atmosphere is warming faster than expected, and that evidence supports the theory that it is being caused by human activity. The study predicts that the world’s average surface temperature will rise 2.5 to 10.4 degrees Fahrenheit between 1990 and 2100. The IPCC’s 1995 estimate had only projected an increase of 1.8 to 6.3 degrees. The higher temperatures will cause glaciers to recede, pushing sea levels between 3.54 and 34.64 inches higher, the study says. Tens of millions of people living in low-lying areas will be displaced by the rising sea levels. The report also supports the conclusions of a 1998 study arguing that the last few decades of the twentieth century were warmer than any other comparable period in the last 1,000 years (see April 23, 1998). The IIPC’s 1,000 pages-plus report, written by 123 lead authors from all over the world, drew on the work of 516 contributing experts. At a news conference coinciding with the report’s release, IPCC chairman Robert Watson says, “We must move ahead boldly with clean energy technologies and we should start preparing ourselves for the rising sea levels, changing rain patterns and other impacts of global warming.” [Intergovernmental Panel on Climate Change, 2001; Reuters, 1/22/2001]

Entity Tags: Robert Watson, Intergovernmental Panel on Climate Change (IPCC)

Timeline Tags: Global Warming

Jana Goldman, the public affairs officer at NOAA’s Oceanic and Atmospheric Research (OAR) division, writes in an email to a scientist from the Geophysical Fluid Dynamics Laboratory (GFDL), “If you get any press requests for IPCC please bump them to public affairs before you agree to an interview.” [Emphasis in original] Her mention of “IPCC” is a reference to the Intergovernmental Panel on Climate Change’s recently released third assessment report, which found “new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities.” (see January 22, 2001) Responding to Goldman’s request, the scientist writes, “It seems cumbersome at best. If this policy is implemented, it will greatly cut-down on NOAA scientist interviews.” [Maassarani, 3/27/2007, pp. 52-53 pdf file]

Entity Tags: Jana Goldman

Timeline Tags: Global Warming

Joe Barton, the chairman of the House of Representatives committee on energy and commerce, begins an inquiry into the careers of climate scientists Michael Mann, Raymond Bradley, and Malcolm Hughes. The three scientists had published a study in 1998 (see April 23, 1998) concluding that the last few decades were warmer than any other comparable time in the last 1000 years. Barton’s investigation is spurred by a recent report in the Wall Street Journal reporting that an economist and a statistician, neither of whom have a background in climate science, have found that the study was flawed. Barton’s investigation is demanding that the three scientists provide the committee with details about their funding sources, methodology, and other studies they have published. Barton, who has close ties to the fossil-fuel lobby, “has spent his 11 years as chairman opposing every piece of legislation designed to combat climate change,” notes the Guardian of London. Responding to Barton’s actions, 18 of the country’s most influential scientists from Princeton and Harvard write in a letter: “Requests to provide all working materials related to hundreds of publications stretching back decades can be seen as intimidation—intentional or not—and thereby risks compromising the independence of scientific opinion that is vital to the pre-eminence of American science as well as to the flow of objective science to the government.” Barton’s investigation also draws criticism from within his own party. Sherwood Boehlert, the chairman of the house science committee, says she objects to what she sees as a “misguided and illegitimate investigation.” [USA Today, 7/18/2005; Guardian, 8/30/2005] Congress eventually asks the National Academy of Sciences to review the issue. A year later, the Academy will publish a report confirming that the last few decades have been hotter than any other period since 1600. However, it says there is not enough data to make a solid conclusion regarding temperatures before that time (see June 22, 2006). [San Francisco Chronicle, 6/23/2006]

Entity Tags: Raymond Bradley, Malcolm Hughes, Michael Mann, Joe Barton

Timeline Tags: US Environmental Record, Global Warming

A National Academy of Sciences study concludes that the last few decades were warmer than any other comparable period in the last four centuries. The study’s findings are based on evidence from tree rings, boreholes, retreating glaciers, and other indicators of past surface temperatures. The study was commissioned by Congress in 2005 to investigate whether the claims made in a controversial 1998 climate study by climate scientist Michael Mann are true. That study had concluded that the climate is now warmer than any other time in the last 1,000 years. Mann had also reported in his study that the 1990s were the warmest decade, and 1998 the warmest year. The authors of the current study say they were unable to draw any solid conclusions about temperatures extending beyond the last 400 years for lack of reliable data. Nonetheless, they do agree that available evidence indicates that Mann’s conclusion regarding the last 1,000 years is indeed “plausible.” “Based on the analyses presented in the original papers by Mann et al and this newer supporting evidence, the committee finds it plausible that the Northern Hemisphere was warmer during the last few decades of the 20th Century than during any comparable period over the preceding millennium,” the report concludes. [National Research Council, 2006; National Academies, 6/22/2006; San Francisco Chronicle, 6/23/2006; BBC, 6/23/2006]

Timeline Tags: Global Warming

The UN’s Intergovernmental Panel on Climate Change issues a summary of its fourth report concluding for the first time that global warming is “unequivocal.” The authors of the report also conclude that there is a 90 percent likelihood that greenhouse gases produced as a result of human activities have been the main cause of global warming since 1950. In its last report (see January 22, 2001), the panel made the same assessment, but with a confidence level of only 66 to 90 percent. The 20-page summary, meant for policymakers, will be followed by four technical reports that will be completed and published later in the year. The panel’s conclusions are based on “a three-year review of hundreds of studies of past climate shifts; observations of retreating ice, warming and rising seas, and other changes around the planet; and a greatly expanded suite of supercomputer simulations used to test how the earth will respond to a growing blanket of gases that hold heat in the atmosphere,” the New York Times reports.
Partial list of conclusions -
bullet Global temperatures will increase 3.5 to 8 degrees Fahrenheit if carbon dioxide concentrations in the atmosphere attain levels twice that of 1750, before the Industrial Revolution.
bullet Concentrations of carbon dioxide have reached a level not seen during the last 650,000 years, and the rate of increase is beginning to accelerate.
bullet Even a moderate warming of the global climate would likely result in significant stress to ecosystems and change longstanding climate patterns that influence water supplies and agricultural production.
bullet Sea levels will likely rise between 7 and 23 inches by 2100 and continue rising for at least the next 1,000 years.
bullet “It is very likely that hot extremes, heat waves, and heavy precipitation events will continue to become more frequent.”
bullet The panel expects that precipitation will increase at higher latitudes, while rainfall will likely decrease at lower latitudes. Semi-arid subtropical regions could see 20 percent less rain.
bullet Oceans will absorb billions of tons of carbon dioxide which will form carbonic acid, thus lowering the pH of seawater and harming certain kinds of marine life such as corals and plankton.
bullet If the level of greenhouse gases continues to grow, average temperatures by the end of the century could reach temperature not seen since 125,000 years ago when ocean levels were 12 to 20 feet higher than they are now. Much of that extra water is currently locked in the ice sheets of Greenland and Antarctica, which are beginning to melt. While there is evidence that the glaciers and ice sheets in the Arctic and Antarctic could flow seaward far more quickly than current estimates predict, the climate change panel did not include this in its assessment because it is forbidden by its charter to engage in speculation. According to Michel Jarraud, the secretary general of the United Nations World Meteorological Organization, “the speed with which melting ice sheets are raising sea levels is uncertain, but the report makes clear that sea levels will rise inexorably over the coming centuries. It is a question of when and how much, and not if.”
bullet The harmful consequences of global warming can be lessened if governments take prompt action.
Responses -
bullet Achim Steiner, executive director of the United Nations Environment Program, which administers the panel along with the World Meteorological Organization, says: “In our daily lives we all respond urgently to dangers that are much less likely than climate change to affect the future of our children. Feb. 2 will be remembered as the date when uncertainty was removed as to whether humans had anything to do with climate change on this planet. The evidence is on the table.”
bullet John P. Holdren, an energy and climate expert at Harvard, who is the president of the American Association for the Advancement of Science, says the report “powerfully underscores the need for a massive effort to slow the pace of global climatic disruption before intolerable consequences become inevitable.… Since 2001, there has been a torrent of new scientific evidence on the magnitude, human origins and growing impacts of the climatic changes that are under way. In overwhelming proportions, this evidence has been in the direction of showing faster change, more danger and greater confidence about the dominant role of fossil-fuel burning and tropical deforestation in causing the changes that are being observed.”
bullet Richard B. Alley, one of the lead authors and a professor at Pennsylvania State University, says: “Policy makers paid us to do good science, and now we have very high scientific confidence in this work—this is real, this is real, this is real. The ball’s back in your court.” [Intergovernmental Panel on Climate Change, 2/2/2007 pdf file; New York Times, 2/3/2007; Independent, 2/3/2007]

Entity Tags: Michel Jarraud, John P. Holdren, Intergovernmental Panel on Climate Change (IPCC), Achim Steiner, Richard B. Alley

Timeline Tags: Global Warming

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