What is the Biggest environmental Problem?

Climate change no longer ranks first on the list of what Americans see as the world’s biggest environmental problem, according to a new Washington Post-Stanford University poll.

Just 18 percent of those polled name it as their top environmental concern. That compares with 33 percent who said so in 2007, amid publicity about a major U.N. climate report and Al Gore’s Oscar-winning documentary about global warming. Today, 29 percent identify water and air pollution as the world’s most pressing environmental issue.

Still, Americans continue to see climate change as a threat, caused in part by human activity, and they think government and businesses should do more to address it. Nearly three-quarters say the Earth is warming, and just as many say they believe that temperatures will continue to rise if nothing is done, according to the poll.

The findings, along with follow-up interviews with some respondents, indicate that Washington’s decision to shelve action on climate policy means that the issue has receded — even though many people link recent dramatic weather events to global warming. And they may help explain why elected officials feel little pressure to impose curbs on greenhouse gas emissions.

“I really don’t give it a thought, ” said Wendy Stewart, a 46-year-old bookkeeper in New York. Although she thinks warmer winters and summers are signs of climate change, she has noticed that political leaders don’t bring up the subject. “I’ve never heard them speak on global warming, ” she said. “I’ve never heard them elaborate on it.”

Michael Joseph, 20, a student at the Wentworth Institute of Technology in Boston, said he sees extreme weather-related events such as the Colorado wildfires and the derecho storm that struck Washington on Friday as “having something to do with climate change.” But, like Stewart, he added, “I don’t really hear about it that much.”

The poll, conducted by phone between June 13 and 21, included 804 adults nationwide and has a margin of error of 4.5 percentage points.

Some who feel passionately about the issue say they have noticed that President Obama is no longer pushing a bill that would limit greenhouse gas emissions and allow emitters to trade pollution credits, a system known as “cap and trade.” That proposal stalled in the Senate in 2010.

“I know that he has to pick his battles, ” said Margaret Foshee, 52, of Arlington County, who works in a ski shop after spending much of her career as a nurse. Describing herself as “a big Obama supporter, ” Foshee said she hopes the president will do more to address climate change if he wins a second term. “If you don’t take a stand on this, we’re all doomed. . . . We’ve got to do something even if no one else’s doing it. America should be a leader on a project like this.”