Climate change kills. In 2005 the World Health Organisation estimated that climate change caused by human activity claims more than 150,000 lives annually. More recently, the Climate Vulnerability Monitor placed the death toll at around 400,000. Using the Value of Statistical Life proposed by the US Environmental Protection Agency, this represents a cost of more than $3 trillion. Independent of the source, inaction on climate change is expected to increase death and suffering.
Climate change affects human health in three ways: directly, due to extreme weather; indirectly, via environmental and ecosystem changes; or through societal systems. Extreme weather events such as heatwaves and flooding can be deadly. During the summer of 2003 there were more than 14,000 heat-related deaths in France alone. The frequency and magnitude of extreme weather events are expected to increase, threatening life in both developed and developing countries.
The second pathway is characterised by changes in biodiversity. Warmer conditions and changes in precipitation facilitate the expansion of disease-carrying vectors, such as mosquitoes and ticks. They can also increase the risk of waterborne diseases, such as diarrhoea, partly by causing an increase in fly populations. No consensus regarding the dispersion of vector-borne diseases like malaria has been reached, but global warming will impact surveillance and control activities.
The societal pathway has the highest death toll. Crop failures can cause undernutrition and stress while population displacement can spark violent conflicts. Food availability is disrupted and food access is hit by fluctuation in individual incomes. Demographic pressure and rapidly changing diets are modifying the global food system, driving up demand for agricultural resources such as land and fertilisers. These supply and demand pressures undermine food security. When food scarcity is combined with loss of access to drinking water and compromised health, the cost of undernutrition can be immense.
Climate change will divide the world into winners and losers, since temperate areas may benefit from milder temperatures or less risk of flooding. But the overall impact is expected to be negative and the unfair distribution of winners and losers only increases the need for action. Climate change is likely to exacerbate food insecurity in areas that currently suffer hunger and undernutrition. By 2030 it is expected that more than 98% of deaths related to climate change will occur in developing countries. Sub-Saharan Africa and southern Asia are particularly vulnerable. Countries with weak, inflexible healthcare systems will bear most of the costs. Some people will find it harder than others to move to less vulnerable areas. Climate change is already affecting behaviour in terms of residential location, energy consumption and food safety requirements.
The relation between climate change and violent conflict remains uncertain due to lack of data. However, by adding to the risks faced by the world’s poorest people, climate change can aggravate existing conflicts without being a direct cause. Pastoral systems may risk extinction or be forced to expand seasonal movements to keep livestock alive, provoking conflict with other communities.
Over the past few months the developed world has failed to cope with massive human displacement. It is difficult to imagine that displacements caused by global warming will be small. Action on climate change will provide more opportunities to help vulnerable areas, avoiding the need for people to move to other countries. Inaction will increase refugee numbers and hamper efforts to improve global health.
Economics allows us to compare the costs and benefits of efforts to combat global warming. The Canadian prime minister, Justin Trudeau, has pledged $2.65 billion over the next five years to help developing countries fight climate change. Governments of 20 countries will seek to double their investment in clean energy research and development over five years. Meanwhile, the private sector, led by Bill Gates, has announced a multi-billion dollar clean energy fund. Unfortunately, the scale of the health costs of climate change leaves a lot more room for action.
Article published in The Economist