More deaths from extreme heat. Longer allergy seasons. Increasingly polluted air and water. Diseases transmitted by mosquitoes and ticks spreading farther and faster.

Those are among the health risks that could be exacerbated by global warming coming decades, the Obama Administration warned in a new report.

The study, more than 300 pages long and several years in the making, focuses on what the White House has described as one of the gravest threats to the US: major health problems associated with climate change.

Meanwhile, the Guardian reports that climate change could cut the value of the world's financial assets by US$2.5 trillion. A researcher at the London School of Economics, Professor Simon Dietz, has made the first cost of climate change estimate from economic modelling.


Keeping global warming below the 2C limit agreed at a summit in Paris, would see the value of financial assets falling by US$315 billion less, even when the costs of cutting emissions are included, the Guardian said.

In the worst case scenarios, the losses could soar to US$24 trillion, or 17 per cent of assets, wrecking the global economy.

The US government report details direct effects of climate change, such as the potential for worsening air quality to trigger thousands more premature deaths from respiratory problems or an uptick in annual deaths from crushing heat waves.

But researchers said other, less obvious, effects also could take a toll on human health - from mental health problems that can result from extreme weather events such as hurricanes and floods to the fact that rising carbon dioxide in the atmosphere can lower the nutritional value of some crops.

Administration officials said the brunt of the harm is most likely to fall disproportionately on the most vulnerable populations, such as pregnant women, children, the poor, the elderly, minorities, immigrants and people with disabilities.

"This isn't just about glaciers and polar bears. It's about the health of our family and our kids," Gina McCarthy, administrator of the Environmental Protection Agency, said. "To protect ourselves and future generations, we need to understand the health impacts of climate change that are already happening, and those that we expect to see down the road."

Today's report, which involved scores of researchers and the work of eight federal agencies, included findings largely in line with a growing body of research into the risks to human health should countries continue to emit massive levels of greenhouse gases into the atmosphere. Last year, for instance, a major report in the medical journal the Lancet, which relied on dozens of scientists from China and Europe, found that climate change "threatens to undermine the last half century of gains in development and global health" if left unchecked.

The Obama administration found that as the world warms, exploding populations and greater urbanisation could increase the number of people exposed to extreme heat, which already kills thousands of Americans each year. For instance, researchers projected that a warmer future could result in "thousands to tens of thousands of additional premature deaths per year across the United States by the end of this century" from heat-related illnesses, more than off-setting any reduction of cold-related deaths.

"The changes are happening right now," said US Surgeon General Vivek Murthy. He said that with the data in the new report, "we see a more clear picture of the extent to which climate change is going to impact health, and it's not a pretty picture. . . . As far as history is concerned, this is a new type of threat that we're facing. . . . The solution is not going to be simple, but it is possible."