The global warming conundrum has been on full display over the past 24 hours. Even as one of the nation's most prominent climate scientists has decided to retire in order to become a full-time activist, a new Pew Research poll suggests public interest and intensity with the issue is waning.

James E. Hansen, who directs the Goddard Institute of Space Studies in New York City, has been warning policymakers about the threat of climate change since 1988. And while he remains one of the nation's most outspoken activists on global warming, he decided he needed to pursue the cause full time rather than juggle his outside activities with a full-time job.

Hansen's retirement comes as a new poll out Tuesday suggests he -- as well as President Obama, who has identified climate change as one of his top second-term priorities -- face a major challenge in convincing the public of the urgency of the issue.

A new Pew poll shows the percentage who say that global warming is a "very serious" problem has slipped six points since October.

While Pew reported an identical uptick in the number calling it “somewhat serious”--meaning that more than six in 10 respondents still call climate change somewhat or very serious -- the decline in those who describe it in dire terms means that public attitudes are now around where they were in 2010, close to the lowest level of concern in eight years on the issue.

In short: the American public wants elected officials to do something about global warming, but only a fraction of these citizens are willing to prioritize the issue. In an e-mail Tuesday, Hansen wrote that forcing the federal government to act on the matter "is difficult," even if activists make an appeal to the courts.

"It likely requires public pressure," he wrote. "As in the case of civil rights, the courts do not get too far ahead of public opinion. That is why it is so important to clarify the communications, and our failure as a scientific community to communicate clearly the urgency of actions to stabilize climate."

Capital Insight survey research analyst Scott Clement contributed to this report.

RELATED: 8 things you should know about the Keystone XL project