http://link.toolbot.com/nytimes.com/60052

Pelosi Backs Restrictions on Heat-Trapping Gases
By CORNELIA DEAN
The United States has to cut its greenhouse gas emissions in half by 2050, and mandatory restrictions are the only way to do it, Speaker Nancy Pelosi told the House Science and Technology Committee yesterday.

Ms. Pelosi added that even though she had once opposed using nuclear power to supply some energy needs, she now believed that it should be “on the table,” if the disposal of radioactive waste could be settled.

The speaker said she hoped that the House would consider bills on global warming by July 4.

Ms. Pelosi spoke along with four climate scientists who worked for the Intergovernmental Panel on Climate Change, the United Nations-sponsored group that issued its latest report last week.

The witnesses were Susan Soloman, a senior scientist at the National Oceanographic and Atmospheric Administration; Richard Alley, a professor of geosciences at Pennsylvania State University; and Kevin Trenberth and Gerald Meehl, both of the National Center for Atmospheric Research.

On the whole, the group received a friendly reception, with little challenge to the central conclusion of the panel, that Earth’s climate is warming and that human activity like burning fossil fuels is almost certainly the cause.

Many of the lawmakers’ questions were on technical topics. The questions included how to discriminate naturally occurring carbon dioxide in the atmosphere from gas produced by burning fossil fuels. The gases contain different isotopes of carbon.

Another question asked whether the scientists had confidence in the panel’s decision to moderate its worst-case model for an increase in sea level in the 21st century. New data on ice movement may call into question the model.

A committee member, Representative Dana Rohrabacher, Republican of California, said he did not believe “the so-called consensus” on climate.

Mr. Rohrabacher asked Dr. Soloman how much human activity contributed to greenhouse gases in the atmosphere and interrupted repeatedly when she tried to answer, accusing her of “dodging” and questioning her honesty.

When Dr. Soloman asked for a chance to finish a sentence, he said: “I control this time. You don’t.”

Eventually, Dr. Soloman said atmospheric carbon dioxide had held steady at 280 parts per million for almost 10,000 years, until the beginning of the Industrial Revolution. Today, the level is 380 parts per million and increasing, she added, with “greater than 90 percent” of the increase because of people.

When Mr. Rohrabacher again accused her of dodging his question, the committee chairman, Representative Bart Gordon, Democrat of Tennessee, told him to put it in writing and added, “My belief is the answer lies in what the lady just said.”