A quartet of prominent American researchers staunchly defended the reality of human-caused climate change and stood united on the need for immediate steps to reduce emissions of greenhouse gases, in testimony before Congress yesterday.
Under questioning from lawmakers on the , scientists from top U.S. research institutions—three of whom have contributed to reports of the UN (IPCC)—balked at the insinuation that assaults on climate science have damaged the credibility of the warming consensus.
"Warming is unequivocal. The evidence for a human footprint is very, very strong, and the prospect of continued warming in the future is very strong," said Chris Field, director of the department of global ecology at the of Washington and a co-chair on the new IPCC report due in 2014.
"There are important unknowns, but many of the unknowns are in the direction of risks that are potentially higher."
Field noted that the consensus reports of the IPCC are considered conservative and do not include potential hazards posed by sudden sea level rise and carbon release from ecosystems.
The other scientists made similar observations.
"People tend not to appreciate how conservative the IPCC process is," said Dr. James McCarthy, professor of oceanography and Harvard University and a co-chair of the IPCC report published in 2001.
McCarthy said earlier IPCC scenarios "quite starkly" underestimate sea level rise, adding that the phenomenon has sped up in the last few years. Estimates for sea level rise, he said, are now between two-and-a-half and three-and-a-half feet this century.
James Hurrell, a senior scientist at the National Center for Atmospheric Research and an IPCC contributor, called the global sea-level jump "probably the single best metric of the cumulative global warming."
The hearing came on the same day that 255 scientists from the U.S. National Academies released a strong condemning the "McCarthy-like threats" on scientists and urged action against climate change.
"Society has two choices: we can ignore the science and hide our heads in the sand and hope we are lucky, or we can act in the public interest to reduce the threat of global climate change quickly and substantively," the scientists wrote in the declaration that was published in the journal Science on Friday.
Most National Academies and professional societies have issued statements about climate science, McCarthy said in his written . And last October, the heads of 18 U.S. organizations reaffirmed the consensus on human-caused climate change in a then-unprecedented to senators.
But some members of the Republican minority saw it differently.
"There's clearly a dispute about the evidence," said Rep. John Shadegg (R-Ariz.).
Monckton Urges Do-Nothing Approach