"A lot of things happening together have generated a heightened concern," Max Boycoff of Oxford University Centre for the Environment told Reuters of the report issued to coincide with the UN's World Environment Day on Tuesday.

He said UN reports blaming human emissions from burning fossil fuels for warming that could lead to more heatwaves, desertification, floods and rising sea levels had apparently spurred concerns and far more media coverage.

And freak warm weather in some regions had also probably contributed, as had a documentary by former US Vice President Al Gore about the risks of warming.

In the survey, about 40 percent of those expressing concern wanted governments to restrict companies' emissions of greenhouse gases and wanted more investment in low-emission cars, houses and renewable energy.

Thirty-one percent thought people should recycle more. But only 3 percent said people should reduce air travel.

People in Switzerland, France, Australia and Canada were most worried about climate change, with more than 30 percent rating it among their top two concerns alongside issues such as the economy, health and job security.