People in Latin America are most concerned about the ill effects of climate change while those living in the United States and China—the world's biggest polluters—are the least concerned, an online poll by Pew Research Center showed.

The poll showed that a median of 54 percent of people across 40 nations surveyed believe climate change is a very serious problem.

"Concern over climate change is especially high in Latin America, where a median of 74 percent think it is a very serious problem, followed by sub-Saharan Africa (median of 61 percent)," according to Pew.

A total of 45 percent in Asia and 38 percent in the Middle East expressed significant concerns about climate change.

"And Americans and Chinese, whose economies are responsible for the greatest annual CO2 emissions, are among the least concerned," it said.

Respondents were asked in the ongoing survey to rank their concern about climate change from 3 to 12 with 3 being the least concerned and 12 the most concerned.

Among the 40 nations surveyed, Americans ranked 37th with 8.78, only better that people in Australia, 8.75; Poland, 8.73; and Israel, 8.66.

Brazil topped the poll with 11.42 followed by Uganda, Burkina Faso, Peru, Venezuela, the Philippines, Chile, India, Ghana and Argentina.

"Climate change is not viewed as a distant threat. Across the nations surveyed, a median of 51 percent believe people are already being harmed by climate change and another 28 percent think people will be harmed in the next few years," Pew said.

Latin Americans, it said, expressed the greatest concern about climate change threat while Middle Easterners are the least likely to believe that climate change is currently harming people.

Pew said more than half of the people in 39 of the 40 countries are concerned that global warming will harm them personally during their lifetime, with the United Kingdom as the lone exception.

Latin Americans are the most alarmed with 63 percent followed by sub-Saharan Africans at 61 percent.