TORONTO -- The biggest global health threat of this century is climate change, according to a new report prepared jointly by University College London and The Lancet.
Climate change will change for the worse patterns of disease, food security, water and sanitation, and extreme weather, according to Anthony Costello, FRCPCH, of University College London and colleagues.
"This is a bad diagnosis for our children and grandchildren," Dr. Costello told reporters, not only in the developing world but also in industrialized countries.
The journal's editor in chief, Richard Horton, FRCP, said climate change is "an urgent threat, it is a dangerous threat, it is neglected and requires an unprecedented response."
The researchers called for health professionals to get involved in a new "public health movement that frames the threat of climate change for humankind as a health issue."
The 94-page report is to be published in the May 16 issue of The Lancet.
Dr. Costello said the researchers concluded that mean global temperatures will rise by between 2oC and 6oC over the next 100 years.
Among other things, they said, the increase will mean:
More heat waves like the one in Europe in 2003 that killed an estimated 70,000 people.
Greater rates of transmission and wider geographic spread of diseases such as malaria and dengue fever that are currently endemic in tropical regions.
Hunger from falling crop yields in many regions of the world, caused by higher temperatures and the effects of extreme weather, such as flooding and drought.
An increase in gastroenteritis and water-borne diseases because of disrupted water supply, as well as water shortages.
Co-author Hugh Montgomery, M.D., also of University College London, said the research suggested that one-third to two-thirds of all known species could go extinct over the next 40 years.
That would be the "fastest mass extinction the world has ever seen," Dr. Montgomery said, and would have harmful effects on humanity, a species at the top of the global food chain.
"You don't have to be a genius to recognize that that will impact on your lives," he said.
One possible effect, he said, would be crop failures because of a lack of pollinating insects.
On the other hand, some species would do better, the researchers said, including the insects that carry such diseases as malaria. Also, the vectors that carry animal infections, such as blue-tongue virus, would be able to spread.
Dr. Montgomery said the climate change debate has largely focused on infrastructure and economics, along with questions of weather and "whether the polar bears are going to survive."
One purpose of the report, he said, is to "personalize" the issue.
Nearly a billion people already suffer food insecurity, the researchers noted, and the UN World Food Programme says the number of food emergencies every year has increased from an average of 15 during the 1980s to more than 30 in this decade.
A rise in sea level could also cause "catastrophic" effects, the researchers said, noting that of the 20 largest cities in the world, 13 are on a coast. A sea level rise of only a few meters could inundate many of those places, they said. Dr. Costello noted that aside from slowing or averting climate change, reducing carbon emissions would have some health benefits, including cleaner air and a lower burden of illnesses related to a sedentary lifestyles, such as obesity, diabetes, and stress.
The world might be reaching a "tipping point" in the climate change debate, Dr. Costello said, adding that the health lobby has come late to this debate but must be "at the forefront."
He said that before starting on this project, he – as a pediatrician – had not realized how serious the issue is as a matter of global health.
Dr. Costello said he and other health professionals "must emphasize the (health) threat to our children and grandchildren from greenhouse gas emissions and deforestation."
He added that the focus must be on health care systems, which are not equal throughout the world. Because of that inequality, the "loss of healthy life years" to climate change will probably be 500 times higher in Africa than in Europe.
Finally, he said, "we must develop win-win situations whereby we mitigate and adapt to climate change and at the same time significantly improve human health and well being."