Climate change poses risks to human health just as pollution and lack of sanitation did a century ago, says a medical journal editorial that details the potential harmful health effects and the benefits of reducing greenhouse gas emissions.

In Monday’s issue of the Journal of the American Medical Association, researchers reviewed studies on health risks related to climate change and the value of attempts to mitigate greenhouse gas emissions.

The research is being released as world leaders prepare for the UN summit on climate change in New York on Tuesday.

The researchers said that harm from climate change includes:

  • Respiratory disorders, including those made worse by fine particulate pollutants, such as asthma, and allergic diseases.
  • Infectious diseases, including those transmitted by mosquitoes, and water-borne illnesses, such as childhood gastrointestinal diseases.
  • Food insecurity, including reduced crop yields and an increase in plant diseases.
  • Mental health disorders, such as post-traumatic stress disorder and depression that are associated with natural disasters.

"Evidence over the past 20 years indicates that climate change can be associated with adverse health outcomes," Dr. Jonathan Patz of the Global Health Institute at the University of Wisconsin, Madison, and his colleagues concluded.

Sears Tower

The Sears Tower in Chicago underwent remodelling to include a green roof and solar panels. NASA says green roofs can dramatically reduce the surface temperature of urban environments. (Paul Beaty/Associated Press)

"Health professionals have an important role in understanding and communicating potential health concerns related to climate change, as well as the co-benefits from burning less fossil fuels," Patz said.

The researchers' analysis of the data suggests that in the U.S., many cities will experience more frequent extreme heat days. For example, New York City and Milwaukee could have three times their current average number of days hotter than 32 C, which would exacerbate heat stress.

They also summarize evidence on global trends in temperature, precipitation, sea level rise and ocean acidification.

Climate change and physicians' professional duty

Patz’s team said that reducing use of fossil fuels has documented benefits such as increases in labour productivity and lower costs to the health system.

An editorial that accompanies the study is titled "Climate Change: A Continuing Threat to the Health of the World’s Population."

"The great gains in well-being in the 20th century occurred because of the concerted effort to improve the health of entire populations," Dr. Howard Bauchner concluded in the editorial.

"Today, in the early part of the 21st century, it is critical to recognize that climate change poses the same threat to health as the lack of sanitation, clean water, and pollution did in the early 20th century," Bauchner wrote.

Dr. David Fisman studies infectious diseases and climate change, such as the effect of latitude on tick-borne Lyme disease incidence, at the Dalla Lana School of Public Health at the University of Toronto.

"As physicians, we have a lot of cred," Fisman said in an email. "I think there's a professional duty to advocate for reduced climate risk."

In the short-term in North America, more severe storms, flooding and hotter temperatures are increasingly displacing more people, said Dr. Robert Strang, Nova Scotia's chief medical officer of health.

Strang pointed to prolonged summer heat in France and Chicago in the last few years, where there were increased deaths, especially among seniors.

"As humans, we are no healthier than the state of our environment," Strang said. "We fundamentally need to break down that divide between environment and health."

Aside from reducing greenhouse gases, the study's authors also suggested solutions to mitigate climate change, such as wider use of sustainable energy technologies, a shift in transportation patterns to walking and cycling, and improved building design.

Solar and wind are about to become competitive with fossil fuels, so it's a great opportunity to change norms in society, said Patz, one of the study's authors.

"If you look across transportation, energy and food systems especially, if we are addressing climate change through these systems and getting to a less carbon intense economy, on the one hand we reduce the risk of future climate change. But on the other hand, we have some immediate health benefits, especially through improved air quality, physical fitness and improved diet," Patz said in an interview from New York ahead of the UN summit.

Use of green roofs can dramatically reduce the surface temperature of urban environments, which is critically important for elderly and other sensitive populations, according to NASA.