UN Climate Science Panel Blames Global Warming on Human-Induced Emissions

New Orleans might well have been one of the first major casualties of global warming, according to the UN Intergovernmental Committee on Climate Change, whose much-anticipated report names humanity as the culprit behind climate change, and climate change as the culprit behind more intense hurricanes such as Katrina and Rita. 

Officially launched in Paris this morning, the IPCC report entitled Climate Change 2007 states: “At continental, regional, and ocean basin scales, numerous long-term changes in climate have been observed. These include changes in Arctic temperatures and ice, widespread changes in precipitation amounts, ocean salinity, wind patterns and aspects of extreme weather including droughts, heavy precipitation, heat waves and the intensity of tropical cyclones.”  

The report further 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.” The report’s use of the term “very likely” indicates a certainty of 90 percent. 

The report predicts that global temperatures will continue to rise by a further 3.2 – 7.8 Fahrenheit (1.8 – 4.0 Celsius) by the end of the century. Australian climate change scientist Professor Tim Flannery of Macquarie University described the IPCC predictions as “middle of the road” and told The Age that he is most concerned about “truly catastrophic rises in temperatures … Three degrees (Celsius, or 5.4 degrees Fahrenheit) will be a disaster for all life on earth.” 

Ominously, the report also states that global temperatures will continue to rise for centuries, even if governments succeed in reducing their emissions of greenhouse gases. One of the report’s lead authors, Kevin Trenberth of the US National Center for Atmospheric Research, told Canadian Press: “This is just not something you can stop. We’re just going to have to live with it. We’re creating a different planet. If you were to come up back in 100 years time, we’ll have a different climate.” 

A major concern is the issue of sea levels, which the IPCC predicts will rise by 7-23 inches by the end of the century, with an additional rise of 4-8 inches if the recent and unexpected melting of polar ice sheets continues. 

Carbon emissions-induced global warming is already causing a range of impacts: fewer cold days, hotter nights, severe heat waves, catastrophic flooding, prolonged droughts, and more intense hurricanes and tropical storms.  

One of the last points of agreement for IPCC scientists was global warming’s impact on the increasing intensity of Atlantic hurricanes. Each conclusion in the report was subjected to a rigorous consensus process, which left only indisputable conclusions. After exhaustive debate during the past week, IPCC scientists reached the consensus that there is a link between global warming and more intense tropical storm activity. 

Sea surface temperatures have risen in tandem with global temperatures over the past 50 years. Professor Kerry Emanuel of MIT’s Department of Earth, Atmospheric and Planetary Sciences has long argued that there is a positive relationship between climate change, sea surface temperatures and the increasing intensity of storms in the Atlantic basin. Earlier this week, Professor Emanual told the Associated Press, “I think we’ve seen a pretty clear signal in the Atlantic” because the increase in more powerful hurricanes “is so beautifully correlated with sea surface there can’t be much doubt that there’s a relationship with sea surface temperature.” 

There is disagreement between the IPCC and the World Meteorological Organization regarding the extent to which global warming has caused the increase in major tropical storms since the 1970s. The WMO maintains that the evidence based on historical data is not conclusive. However, there is strong agreement regarding what the future holds – that is, there will be more intense hurricanes like Katrina and Rita if global and sea surface temperatures continue to rise. 

Despite the report’s dire predictions, scientists insist that there is much that humanity can do to prevent the most apocalyptic scenarios. Ideally, the report will instill in policy makers a sense of urgency commensurate with the implications, resulting in effective strategies that significantly reduce greenhouse gas emissions.

“The point here is to highlight what will happen if we don’t do something and what will happen if we do something,” said report co-author Jonathan Overpeck of the University of Arizona. “I can tell if you we decide not to do something the impacts will be much larger than if we do something.”

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