By making environmental protection a moral imperative, Francis' intervention could spur the world's 1.2 billion Catholics to lobby policymakers on ecology issues.

Washington - Americans no longer see climate change as the world's number-one environmental issue, according to a public opinion poll released on Tuesday amid an ongoing heat wave in much of the United States.

Twenty-nine percent cited water and air pollution as the most pressing concern, the Washington Post-Stanford University poll indicated, followed by 18 percent who pointed to climate change - way down from 33 percent in 2007.

More than 800 adults took part in the telephone survey between June 13 and 21, several days before record-setting temperatures unleashed fierce thunderstorms and left millions without power in many states.

The poll - which also followed the warmest spring on record in the United States - had a margin of error of 4.5 percentage points.

While downgrading climate change, nearly three in four poll respondents said the Earth is warming, and just as many felt global temperatures will keep going up if nothing is done to address the matter.

Reporting the poll findings, the Washington Post said the reduced priority given by Americans to global climate change could be due to President Barack Obama's own low profile on the issue ahead of the November election. - AFP