Public Health

Climate change represents an inevitable, massive threat to global health that will likely eclipse the major known pandemics as the leading cause of death and disease in the 21st century.                                                         — Dr. Dana Hanson

Climate change is being driven largely by the extraction and combustion of fossil fuels, resulting in both direct and indirect impacts on human health and the fundamental requirements upon which it is based – clean air, safe drinking water, sufficient food, secure shelter, and disease resistance.

The three main fossil fuels — coal, oil, natural gas — all post serious, ongoing threats to public health, both in extraction and combustion. According to the Clean Air Task Force there are more than 13,000 premature deaths in the U.S. alone from exposure to coal-fired power plants, mining incidents, and toxic coal slurry ponds. In some countries like China the number is far higher — an estimated 100,000 premature deaths per year.

The recent oil spills in the Gulf of Mexico, New Zealand, Nigeria, and China have proven that oil is also dirty business with extremely high costs to human and environmental health. And natural gas, once proposed as a cleaner alternative to petroleum, has resulted in tainted water aquifers through the process of hydraulic fracking.

But the health impacts of fossil fuels do not stop there. In addition to these direct impacts there are many indirect impacts brought about by CO2 gases which are now driving human-made climate change. Researchers have found that there is a close link between climate change and the occurrence or severity of some diseases and other threats to human health. It is estimated that climate change contributes to 150,000 deaths and 5 million illnesses each year, and the World Health Organization estimates that a quarter of the world’s disease burden is due to the contamination of air, water, soil and food. The toll is expected to double to about 300,000 lives per year by 2020.

There are 6 main influencing factors that, as a result of climate change, directly or indirectly impact human health — food supply, air pollutants, heat, disease transmission, storms & flooding, and civil conflict. In some cases one factor may trigger or reinforce another. For instance ground level ozone pollution (or smog) increases under hot and stagnant conditions. Breathing ozone results in lung function and damages the cells lining the lungs.  Similarly, heat can exacerbate the spread of disease.

According to Ross Gelbspan, the Aedes aegypti mosquito (PDF) which spreads dengue and yellow fever has traditionally been unable to survive at altitudes higher than 1,000 meters because of colder temperatures there. But with recent warming trends, those mosquitoes have now been reported at much higher altitudes in Costa Rica and Colombia. Malaria-bearing mosquitos too, have moved to higher elevations in central Africa, Asia, and parts of Latin America, triggering new outbreaks of disease.

Image by ClimateCommunication.org adapted from Boroswki

According to a Journal of the American Medical Association report (PDF), “The relationship between climate change and global health is unmistakable. This is a critical time for public health advocates to demand that political leaders safeguard the health of the world’s population, with particular attention to the survival needs of the most disadvantaged.”

Quick Facts:

• The global warming that has occurred since the 1970s was causing over 140,000 excess deaths annually by the year 2004. [WHO]
• By 2025 there will still be 5 million deaths among children under five – 97% of them in the developing world, and most of them due to infectious diseases such as pneumonia and diarrhoea, combined with malnutrition. [WHO]
• More than 1 million people in developing countries die annually as a result of in-door smoke and
  respiratory diseases resulting from use of inefficient wood and other organic fuels. About 2% of fuel
  for road transport is powered by biofuels, mainly bioethanol. [IPCC]
• Heat is already the leading cause of weather-related deaths in the United States, with more than 6,300 deaths resulting from exposure to extremely hot weather between 1979 and 2006. [WHO]
• High temperatures also raise the levels of ozone and other pollutants in the air that exacerbate cardiovascular and respiratory disease. Urban air pollution causes about 1.2 million deaths each year. [WHO]
• 300 million people are affected by asthma. Pollen and other aeroallergen levels are higher in extreme heat, which can exacerbate asthma. Ongoing temperature increases are expected to increase this burden. [WHO]