Climate Change and Human Health

In the 4th Assessment Report (2007) the UN's Intergovernmental Panel on Climate Change (IPCC) established beyond a reasonable doubt that human activity is altering the Earth's climate. If this vast, unintentional experiment is allowed to continue, average temperatures will rise between 2 and 4 ºC by the end of this century. These environmental disruptions have public health consequences for food security, water access, and infectious diseases, which will hit poor countries the hardest. The good news is that the costs of mitigating these problems is relatively small, on the condition that action is taken swiftly.

Direct Health Impacts

People are exposed to climate change directly through changing weather patterns such as extreme weather events and sea level rise. Heat waves, floods, hurricanes, tornadoes, droughts and fires are all likely to raise accidental deaths and injuries.

According to WHO, approximately 600 000 deaths occurred worldwide as a result of natural disasters caused by extreme weather events in the 1990s, some 95 percent of which took place in developing countries. Even in the developed countries of Southern Europe, a heat wave in 2003 claimed 70,000 lives according to recent figures from the WHO. Coastal areas, especially the heavily-populated mega-delta regions in Asia and Small Island States will be at greatest risk from increased damage due to flooding and storm surges as sea-levels rise.

Indirect Health Impacts

Indirectly, climate change affects infrastructure and ecosystems upon which agriculture and livelihoods depend. Increased child mortality, reduced maternal health and the undermining of the nutritional health needed by individuals to combat HIV and AIDS, are expected to occur as a result of climate change. Populations with already high rates of disease and debility cope less successfully with stresses of all kinds, including those related to climate change.

IPCCs 4th assessment report projects that by 2020, between 75 and 250 million people in Africa will be short of water for all uses, due to climate change. Increase in prevalence of certain vector-borne and water-borne diseases is expected. Climate-disrupted access to clean water will increase the burden of diarrhoeal disease, which currently kills over 1.8 million children every year. Changing weather will also steer infectious disease vectors into new areas. Malaria's overall range may not change, but it will expand into new areas and affect new populations where lack of preparedness will cost lives.

Food Security

Agricultural production in many African countries is projected to be severely compromised; by 2020 their yields from rain-fed agriculture could be reduced by up to 50 percent. Increased occurrence of drought is expected to drive mass migrations to crowded urban areas where they are likely to endure health problems related to nutritional problems, poor shelter and sanitation.

Record-high food prices today have already pushed the world to the brink of a global food crisis, driven by competition for fertile land for crops, animals and even bio-fuels. Continued poor farming practice and deforestation have made agriculture vulnerable to the effects of climate change, a combination which will lay waste vast areas of land.

The worst of climate change has yet to strike the developing world, where child malnutrition is already the cause of over 3.5 million deaths per year. Continued population growth adds to all these pressures.

A Climate of Change

Climate Change is likely to delay or sustain the achievement of the health-related MDGs unless climate-aware action is undertaken to identify and address specific vulnerabilities. Changes need to be made in health care, emergency services, land use, urban design and settlement patterns to protect populations against heat waves, floods, and storms. Measures implemented in the water, agriculture, food, and construction sectors need to be designed to benefit human health.

As a first step, the WHO calls for national level assessments on how existing health systems would cope with the threats described above. One suggestion is for the health sector to perform a review and create models on the same scale as Sir Nicholas Stern did for assessing the economic impacts of climate change. The 2001 report from the Commission on Macroeconomics and Health, led by Jeffrey Sachs, serves as an excellent point of departure for such an effort. The scientists who have sounded the global warning should also put their models at the service of public health experts to improve surveillance and prediction of climate-related regional health impacts.

Even without further assessments, the need is clear for increased capacity to deal with present health challenges and climate variability. Health system strengthening and interventions to control infectious diseases and build capacity for clean water and sanitation should be intensified in order to reach the 2015 Millennium Development Goals. Moreover, there is general agreement that health co-benefits from reduced air pollution as a result of actions to reduce Greenhouse Gas Emissions can be substantial and may significantly reduce mitigation costs. If action is delayed, the same models show much higher costs to control increasing damage.

If successful, the global challenge posed by Climate Change may have a uniquely mobilising effect which will bring much larger awareness and financial commitment to development goals in general.