REYKJAVIK, ICELAND – Two expert scientists, Stefan Rahmstorf of Potsdam University and Michael Mann of Penn State University, provide insights on the most recent report of the Intergovernmental Panel on Climate Change.
“The IPCC has ratcheted-up the level of confidence that not only is the Earth warming, but we know that it is human activity that is responsible for it,” Mann tells independent videographer Peter Sinclair in the November 2013 “This is Not Cool” video for The Yale Forum. He explains that the IPCC Working Group I Fifth Assessment Report, AR5, increased its level of confidence from 90 percent, “very likely,” to 95 percent, “extremely likely.”
That puts the level of confidence on par with that for cigarettes as a cause of cancer, Sinclair says.
The two scientists, both authors of earlier IPCC assessment reports, note that IPCC in AR5 links the observed warming to detectable increases in sea-level rise, to rises in global surface and ocean surface temperatures, to melting of ice, and increases in various extreme weather events, and decline in snow cover and increases in atmospheric water content.
“All of the dangers, all of the changes that they have been predicting have happened on schedule,” Time magazine science editor Jeffrey Kluger told CBS in commenting on the AR5 report.
Rahmstorf noted that the changes now being observed had been predicted long before they actually occurred, for instance in scientific reports dating back to 1965 to then-President Lyndon B. Johnson. Rahmstorf pointed also to reports in Nature and Science in the 1970s making accurate predictions of impacts just now being observed. “It has pretty well happened as it was predicted,” Rahmstorf told Sinclair.
Mann, not one to pull his punches commenting on news media he finds wanting, characterized much of the media coverage of the IPCC AR5 Working Group I report as “pretty good on the whole,” with some exceptions. Sinclair’s video also includes an excerpt of a CNN meteorologist accurately describing the slow-down in warming over the past 16 years or so.
Rahmstorf points to past IPCC underestimates of sea-level rise and of loss of Arctic Ocean sea ice and says IPCC reports are known to be “conservative” in their projections. There are arguments pro and con for its conservative approach, Rahmstorf said, but “The most important thing is that you know that they are conservative so you understand IPCC reports in the correct way.”