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Why climate change is very bad for your health

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…

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.

Join the conversation

7 Comments sorted by

  1. Rog Tallbloke

    logged in via Twitter

    "a prolonged heat wave claimed around 650 excess deaths in England."

    No mention for the 30,000 excess deaths due to winter cold in 2012/13 then? That was a 30% rise on the previous year, and it's been rising 'alarmingly' for several years.

    As for the supposed increase in frequency and intensity of extreme weather events, the author links to IPCC SREX. Maybe we were reading different versions of it? Here are the take-away points mentioned by Roger Pielke:

    (from Chapter 4):
    "There is medium…

    Read more
    1. Brad Farrant

      Adjunct Research Fellow in Early Childhood Development at University of Western Australia

      In reply to Rog Tallbloke


      The overwhelming majority of climate scientists agree that the planet is warming and that most of this warming is caused by human activity?

      Do you accept that?

      We can quibble about the precise size of the impact that this has and will have but there is no doubt that climate change is having negative impacts on human health and wellbeing and that this will get far worse if we don't do what is necessary to prevent dangerous climate change.

  2. John Doyle


    What a really crappy choice we face!
    Do we mitigate the population explosion by letting these unfortunates die early?
    Do we make the population problem worse by having them survive etc?
    Believe it or not it is a choice we face, if not right now since we can't yet see what the population blow out will do to our societies, but in the future, when that choice stares us in the face
    Everything we do that we think is good, moral and righteous makes the population problem worse.
    Of course we don't have to do anything. Nature will do it to us.
    But if we choose wisely now we may avoid being helpless later.
    The "new world order" is beginning to show its stark reality!

  3. DavidNutzuki

    logged in via Facebook

    If science can't be certain that the end is near for billions of innocent then YOU news editors can't tell our kids that science "believes" as much as YOU do.

    *Why won't news editors mention that the scientific consensus was; "could be" and never; "will be"?

    *Why won’t science agree beyond; “could be”?

    *Why won’t the scientists agree in “certainty” like they do for comet hits?

    *Why won’t science end this costly debate to “save the planet” and give the planet a real warning of certainty…

    Read more
    1. John Doyle


      In reply to DavidNutzuki

      That's easy.
      Bertrand Russell neatly explains;
      "The whole problem with the world is that fools
      and fanatics are always so certain of themselves,
      and wiser people so full of doubts"

    2. Brad Farrant

      Adjunct Research Fellow in Early Childhood Development at University of Western Australia

      In reply to DavidNutzuki


      I am not sure what you are trying to say here but if it is that science works with probabilities rather than black and white certainties then of course that is correct.

      But if you are trying to argue that we should disregard what science is telling us about the ramifications of climate change simply because it talks in terms of probabilities then I would have to strongly disagree with you.

      Science is the best tool that we have to understand the world around us and it would be extremely irresponsible to ignore or deny what the scientists are telling us simply because we find it confronting or hard to deal with.

      It is not ok to continue to transfer the costs of our fossil fuel burning behaviour onto the children of today and tomorrow.

  4. Rob Sheppard

    logged in via email

    Side note: A better name for "climate change" or "global warning" would be "climate destabilisation".

    I guess the biggest threat to health is when we run out of air or land or water! According to we will reach a tipping point in the next 15-20 years.

    Several organisations have noted over the years that the largest contributor to climate destabilsation is our reliance on animal agriculture, more than our other energy or transport use combined.

    Also of interest (to the author) is a recent FAO report that linked animal agriculture to 70% of human diseases (not including heart disease, cancer or other diseases caused by eating animals!).

    Why is there no call to move to plant-based diets?