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Why climate change is very bad for your health

Alastair Mackie’s Mosquito Coast. Noodlefish

It is beyond doubt that our emissions contribute to climate change. And climate change is making us sick.

Sea–level rises, changes to the severity of monsoon seasons and rainfall, flooding, droughts and heatwaves are all predicted to have an increasing impact on our health.

The World Health Organisation estimates that between 1970 and 2004, the environmental effects of climate change caused more than 140,000 deaths each year. And the direct financial cost of the damage it will have on our health is estimated to come in at around US$2-4 billion in just over 15 years time.

Extreme weather events

We tend to think of large-scale weather events as “natural” disasters, but the case is increasingly being made for a man-made cause and effect for some of these. While it is difficult to attribute single events such as Hurricane Katrina to climate change, climatologists have suggested a possible role in contributing to the intensity of these kinds of events. And flooding, droughts, heatwaves, and the spread of disease have all been linked to climate change.

In the UK, adverse weather events already have a palpable public presence. Only last year, a prolonged heat wave claimed around 650 excess deaths in England. And according to the authors of a report on the disastrous 2003 heatwave that claimed 20,000 lives across Europe, it is “very likely” that human influence has at least doubled the risk of another particularly bad one happening again.

Julia Slingo, the Met Office’s chief scientist, said that the evidence suggests climate change is likely to be a factor in the severe weather than has caused torrential rain and flooding in the south of England over the past two months. Since December there have been 130 severe flood warnings (compared to nine in 2012) which not only poses an immediate physical risk to people, but also threatens to undermine the country’s food security.

And such climatic events are occurring with increasing severity and frequency across the globe.


We don’t live in isolation from other ecosystems. From large-scale weather events, through to the food we eat daily, right down to the minute organisms colonising our skin and digestive systems, we live and breath in co-dependency with our environment.

A change in the delicate balance of micro-organisms has the potential to lead to disastrous effects. For example, microbial proliferation – which is predicted in warmer temperatures driven by climate change – may lead to more enteric infections (caused by viruses and bacteria that enter the body through the gastrointestinal tract), such as salmonella food poisoning and increased cholera outbreaks related to flooding and warmer coastal and estuarine water.

Changes in temperature, humidity, rainfall, soil moisture and sea-level rise, caused by climate change is also affecting the transmission of dangerous insect-borne infectious diseases. These include malaria, dengue, Japanese encephalitis, chikungunya and West Nile virus, lymphatic filariasis, plague, tick-borne encephalitis, Lyme disease, rickettsioses, and schistosomiasis.

Through climate change, the pattern of human interaction will likely change and so will our interactions with disease-spreading insects, especially mosquitoes. The World Health Organisation has also stressed the impact of climate change on the reproductive, survival and bite rates of insects, as well as their geographic spread.

Climate refugees

Perhaps the most disastrous effect of climate change on human health is the emergence of large-scale forced migration from the loss of local livelihoods and weather events – something that is recognised by the United Nations High Commission on Human Rights. Sea-level rise, decreased crop yield, and extreme weather events will force many people from their lands and livelihoods, while refugees in vulnerable areas also face amplified conditions such as fewer food supplies and more insect-borne diseases. And those who are displaced put a significant health and economic burden on surrounding communities.

The International Red Cross estimates that there are more environmental refugees than political. Around 36m people were displaced by natural disasters in 2009; a figure that is predicted to rise to more than 50m by 2050. In one worst-case scenario, as many as 200m people could become environmental refugees.

Not a level playing field

Climate change has emerged as a major driver of global health inequalities. As J. Timmons Roberts, professor of Environmental Studies and Sociology at Brown University, put it:

Global warming is all about inequality, both in who will suffer most its effects and in who created the problem in the first place.

Global climate change further polarises the haves and the have-nots. The Intergovernmental Panel on Climate Change predicts that climate change will hit poor countries hardest. For example, the loss of healthy life years in low-income African countries is predicted to be 500 times that in Europe. The number of people in the poorest countries most vulnerable to hunger is predicted by Oxfam International to increase by 20% in 2050. And many of the major killers affecting developing countries, such as malaria, diarrhoeal illnesses, malnutrition and dengue, are highly sensitive to climate change, which would place a further disproportionate burden on poorer nations.

Most disturbingly, countries with weaker health infrastructure – generally situated in the developing world – will be the least able to cope with the effects of climate change. The world’s poorest regions don’t yet have the technical, economic, or scientific capacity to prepare or adapt.

Predictably, those most vulnerable to climate change are not those who contribute most to it. China, the US, and the European Union combined have contributed more than half the world’s total carbon dioxide emissions in the last few centuries. By contrast, and unfairly, countries that contributed the least carbon emissions (measured in per capita emissions of carbon dioxide) include many African nations and small Pacific islands – exactly those countries which will be least prepared and most affected by climate change.

Mitigating disaster

So what can and has been done by health professionals to protect our globe and the people we care for from the deleterious effects of climate change? Tony (AJ) McMichael, a professor of epidemiology at the Australian National University, and colleagues suggest a number of strategies to help populations adapt specifically to the health consequences of climate change. These include public education, prevention programmes based around vaccination, mosquito control and nutrition, more healthcare provision for affected communities. Better forecasting of future risks and disease surveillance will also go some way to helping.

Dialogue and momentum

But ultimately, the answer lies not just in cure but in prevention. A recent report from Medact, a group of health professionals dedicated to global issues around conflict, poverty and the environment, recently outlined why the science of climate change matters to people working in health:

Health professionals are not climate scientists. But … global warming is already having a significant negative impact on human health; it threatens to be an overwhelming danger in the coming decades. For this reason, health professionals … need some understanding of climate science as a basis for their active and assertive engagement in policy debates about how we respond to global warming.

Groups like this are integral to sustained focus on climate change and generating political momentum. But beyond this, activism by everyone must also play a role. The direction that our collective governments negotiate is our responsibility. And we must continue to communicate our collective concerns and make choices that are the best for the planet.

Four hats

As a scientist, I believe the overwhelming evidence that climate change is real and is endangering the world; as a doctor, I see the disproportionate impacts on the health of the world’s most vulnerable; as a humanist, I believe in equality and advocating for those without a global voice; and as an optimist, I believe that we can act coherently to mitigate the worst effects of climate change.

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