An overwhelming majority of the world’s environmental scientists are sounding an increasingly desperate alarm about the impending consequences of global warming, but one of the two major US political parties has decided to loudly ignore reality: Whatever Happened to Global Warming?

IN 2008, both the Democratic and Republican candidates for president, Barack Obama and John McCain, warned about man-made global warming and supported legislation to curb emissions. After he was elected, President Obama promised “a new chapter in America’s leadership on climate change,” and arrived cavalry-like at the 2009 United Nations Climate Conference in Copenhagen to broker a global pact.

But two years later, now that nearly every other nation accepts climate change as a pressing problem, America has turned agnostic on the issue.

In the crowded Republican presidential field, most seem to agree with Gov. Rick Perry of Texas that “the science is not settled” on man-made global warming, as he said in a debate last month. Alone among Republicans onstage that night, Jon M. Huntsman Jr. said that he trusted scientists’ view that the problem was real. At the moment, he has the backing of about 2 percent of likely Republican voters.