Not enough evidence exists that humans are responsible for global warming, so current laws should not be changed to limit greenhouse gas emissions, critics of a global climate change report told a House panel Thursday.
Scientists and lawmakers at the House Science and Technology Committee debated the findings of a recent report by the Intergovernmental Panel on Climate Change, which said the probability that humans are responsible for global warming is greater than 90 percent. That's an increase from its 2001 estimation that put the probability at 66 to 90 percent.
"The newly released report reaffirms the strong scientific evidence that human
activities are changing the composition of the planet’s atmosphere, and that this is warming
the climate and affecting it in other ways," said Richard Alley, a geosciences professor at Penn State University and one of the IPCC report's authors.
"Strong evidence for the dominant role of warming, which is primarily being caused by human activities" is the reason for "widespread reductions in the Earth’s ice, including snow, river and lake ice, sea ice, permafrost and seasonally frozen ground, mountain glaciers and the great ice sheets of Greenland and Antarctica," he added.
The report, released last week, was put together by 600 authors from 40 countries. But scientist Chris Landsea, who worked on other reports from the IPCC, a U.N. group, withdrew from participating in the project. An expert on hurricanes and typhoons, he said the report is being motivated by "preconceived agendas" and some of the conclusions are "scientifically unsound."
That kind of conflicting claim about the dangers of global warming led to testy exchanges between lawmakers and scientists at Thursday's hearing. Rep. Dana Rohrabacher, R-Calif., is one of several Republicans concerned that Congress will act on the report in a way that hurts businesses and the economy.
Rohrabacher asked the co-chairwoman of the IPCC what percentage of greenhouse gases are caused naturally rather than by human beings. Chairwoman Susan Solomon said carbon dioxide emissions, the biggest contributor to greenhouse gases, "is caused almost entirely by human beings."
Pressed again, she said: "A fair number, regarding the increase since 1750, is that greater than 90 percent of the increase is caused by human activities."
"That wasn't the question, was it?" Rohrabacher retorted. "Listen, this is very dishonest, you're supposed to be a scientist."
Speaking to FOXNews.com, the congressman said Solomon's answer was "a total obfuscation" that "tries to exaggerate the actual amount of pollution being put into the atmosphere by human beings as compared to what nature does itself."
Rohrabacher explained that the answer he got does not reveal that perhaps only 5-10 percent of all greenhouse gases are made by humans even if the human contribution has increased by 90 percent over the last 100 years.
He added that it "makes no sense at all" to defund certain programs and "dramatically change our way of life" when "one volcano is going to undo" all the improvements.
Rohrabacher said another scientist testifying at the hearing, Kevin E. Trenberth of the National Center for Atmospheric Research, acknowledged that a graph he used in his testimony demonstrates an upward trend in temperature, but does not make clear that the starting point of 1850 was at the very end of a 500-year cooling period, a fact Trenberth readily admitted.
Rohrabacher said the graph, therefore, shows a "one degree change from the bottom. That doesn't sound very alarming to me." He also faulted scientists who use scare tactics to make their case.
"We've seen this over and over again, where they are trying to claim an almost unanimous consensus among scientist and it's not true. Usually that tactic is nothing more than just trying to stampede people than answer serious criticism," Rohrabacher said.
Democratic House Speaker Nancy Pelosi, who appeared as a witness in the hearing, said scientific evidence shows that cutting global greenhouse gas emissions in half from today's levels by 2050 will prevent the most severe effects of global warming. She said such cuts will require mandatory limits on emissions and changes in U.S. land-use policies, "since the loss of forests currently contributes about 25 percent of global carbon dioxide emissions."
"We know there will be impacts on coal industry and other industries and we want to hear what those industries have to say so this isn't about roughshod, it's about working together and hopefully we can work with the president of the United States in order to do this. I see it as an economic opportunity, a place where green can be gold for our country," said Pelosi of California.
Pelosi also discussed the creation of a House Select Committee on Energy Independence and Global Warming.
She designed the panel to raise the visibility of climate change and provide recommendations on "policies, strategies, technologies and other innovations intended to reduce the dependence of the United States on foreign sources of energy, and to achieve substantial and permanent reductions in emissions and other activities that contribute to climate change and global warming." The body will not have legislative authority, she noted.
Pelosi said the findings by the IPCC present an economic opportunity for businesses and scientists to innovate more earth-friendly practices, and urged the U.S. government to work with China, which will surpass the United States in three years as the largest contributor to carbon dioxide emissions.
But the international component of greenhouse gas emissions is exactly what led Rep. James Sensenbrenner, R-Wis., to object to such rigorous strains on U.S. businesses.
"I would ask you to look at the impact on America jobs because we do not want to have anything we do result in the outsourcing of American jobs to countries like China, India and Mexico, who have not capped or even slowed down their growth of greenhouse gas emissions," Sensenbrenner said.
FOX News' Molly Henneberg contributed to this report.