"Scientists are inherently skeptical," says Lonnie Thompson, a paleoclimatologist at Ohio State University, who has led studies of glaciers and ice sheets in 16 countries. "After enough evidence and observation, though, you have to start to accept findings. That is what happened with climate change. This wasn't a rash conclusion."
"There is not any serious debate about whether anthropogenic climate change is happening," says Daniel Sarewitz, co-director of the Consortium for Science, Policy and Outcomes at Arizona State University and a professor of science and society. "Scientists are certain about that, and it is unfortunate that the national debate is lagging so far behind."
The public and political discourse on global warming was framed by the 2007 report of the UN Intergovernmental Panel on Climate Change (IPCC), which concluded that climate change is occurring and human activity is the cause. That seminal report, and the subsequent coverage and debate, split the country into two partisan camps, with Democrats generally accepting the scientific consensus and Republicans questioning or flat-out denying it.
Missing from the discussion is the perhaps surprising, and rising, view of many scientists—that the UN climate panel gravely underestimated the immediacy and danger of global warming.
The IPCC process itself is partly, though not entirely, to blame. "It takes seven years to produce an IPCC report," says Thompson, who is also an IPCC author. "By the time it is published, the science is already dated ... and the models being used aren't accurately assessing how rapidly these changes are taking place."
There are real-world implications at stake, Thompson says. "We are in for tougher scenarios than what are being relayed in the reports."
A Flawed IPCC Assumption
At the core of its assessments are IPCC "scenarios"—summaries of coming climatic conditions like global temperature and sea-level rise, which are based on a number of assumptions about future greenhouse gas emissions. One of those assumptions is that the world will make good on its carbon-cutting pledges.
Therein lies a key flaw, says John Reilly, co-director of the Massachusetts Institute of Technology's (MIT) Joint Program on the Science and Policy of Global Change and an expert on climate economic models. Many nations have failed to take promised steps to slash global warming emissions, particularly China and the United States, the world's biggest polluters. Even in the European Union greenhouse gases are on the rise. Yet the IPCC doesn't account for this.
More here: http://www.insideclimatenews.org/news/20120604/climate-change-scientists-global-warming-ipcc-report-scientific-consensus-skeptics-humans-ice-sheets-meltin