What is the evidence for global climate change? How can it be combated? Can our political system respond effectively to the threat of catastrophic changes in the environment?

Daniel Schrag, Sturgis Hooper Professor of Geology and professor of environmental science and engineering, addressed these questions with members of the Class of 2014, who filled Science Center B Friday (Aug. 27) for the 2010 Opening Days lecture. The talk, titled “Twilight of the Anthropocene? Confronting the Climate-Energy Challenge and the Future of Human Civilization,” was a preview of Schrag’s new course.

After a short introduction and welcome from Professor Jay Harris, chair of Harvard’s Standing Committee on General Education, Schrag took the podium. He projected a graph of changes in the amount of carbon dioxide in the atmosphere over the past 650,000 years. There have been increases in CO2 throughout the Earth’s history, he said, some of them quite abrupt. Yet even these took place over periods of around 10,000 years. Since fossil fuels became a major energy source only 150 years ago, however, carbon levels have skyrocketed to almost unprecedented levels. As a result, the global climate is now in uncharted territory.

“We haven’t seen this in 35 million years, so we can’t make an accurate prediction,” he said. “The last time carbon levels looked like this, palm trees flourished in Wyoming.”

Responding to critics who call climate change concerns alarmist, Schrag said that the danger for humanity is actually that science is too conservative. He said that scientists seek a “95 percent confidence interval” before making a claim about a phenomenon or its consequences. As a result, policymakers treat climate change as a “high-consequence, low-probability” event, even as the process accelerates.

Schrag listed possible solutions to the problem — including conservation, alternative energy, and carbon capture and storage — but said that the biggest obstacles for humanity were political rather than technological. Wyoming, for instance, gets 95 percent of its electricity from coal, a major source of CO2 emissions, while Massachusetts gets only 25 percent of its power from it. Both states have two votes in the U.S. Senate, however, even though the population of Massachusetts is many times that of Wyoming. This makes it difficult to pass climate or energy legislation.

“Politically, this is a big challenge,” he said. “There are winners and losers.”

After his remarks, Schrag took questions from the audience, and members of the Class of 2014 were eager to engage him. One student, Michael Lukas, asked if policymakers ought to focus their efforts on conservation or on attempts to adapt to climate change.

“We have to do both,” said Schrag, a member of President Obama’s Council of Advisors on Science and Technology. “If we burn all the coal, we’re in real trouble. At the same time, we’re experiencing real climate change right now.”

Student Nick Perkons asked if it was possible that atmospheric carbon would stabilize on its own, albeit at a very high level.

“We know enough about the carbon cycle to know that CO2 will go up if we continue to burn fossil fuels,” Schrag replied. “I’ve got no problem with palm trees in Wyoming or crocodiles in Greenland. The problem is that we’re adapted to this world. So it’s about the rate of change.”

The session was sponsored by the Harvard College Program in General Education.