Health and Climate Change


Devising health policies to address climate change

Chris Whitty

Professor Sir Chris Whitty KCB FRCP FFPH FMedSci is Chief Medical Officer (CMO) for England, the UK Government’s Chief Medical Adviser and head of the public health profession.


  • Climate change will have negative effects on health everywhere, but there will be gradations in severity
  • The healthcare sector needs to get as close to net zero as possible
  • Policies that have co-benefits for both mitigation and health should be prioritised
  • Countermeasures must be developed against diseases and conditions that will increase with climate change
  • Policy goals have costs and the trade-offs need to be acknowledged and minimised.

It is widely accepted that climate change is one of the greatest long-term threats to human health.  Climate change effects, once they take hold, are not going to be reversed in the foreseeable future. Even if a resulting health impact itself appears modest, a modest effect for an indefinite period is potentially a major issue. 

The negative effects of climate change on health will not be distributed evenly across the globe.  There are scientific reasons (biology, atmospheric physics, etc) and reasons of economic and social development.  To start with science: there will be an increase in the destructive power of storms and, in essence, this will occur where there are already storms.  For people living in the Caribbean, the eastern seaboard of India or parts of Southeast Asia where storms already cause substantial damage, the impact will be large; for other areas it will be smaller.

Other areas will face longer dry periods that could lead to drought and thence to hunger and famine.  While that sequence is not inevitable, there is a broad correlation.  Again, these effects will be distributed differently in different parts of the world.  Such scenarios can be repeated for many different factors and their geographical distribution is not going to be even. 

The effects will be exacerbated, though, by the fact that there is also much greater vulnerability to them in some environments than in others.  This is largely driven by socio-economic factors.  Someone living in the Sahel, for example, will be adversely affected by climate change earlier than someone living in Yorkshire.  Vulnerability is however much greater there too, as those with lower incomes have fewer choices and face greater risks.   Therefore, the impact on individual lives and on human health will be greater.  To be clear, the negative effects on health will be everywhere, but there will be gradations in severity and the least wealthy will suffer the greatest effects wherever they live.

Looking specifically at the UK and Europe, there will be direct effects like increases in heat stress.  This was seen in Paris a few years ago, with significant impacts on mortality for people with cardiovascular and other risk factors.  There will be increased flooding which can cause mental and physical health effects.  These impacts of climate change have direct, negative health impacts. 

Then there are also multiple indirect effects.  Important vector-borne diseases will change their range.  There are a large number of negative consequences from indirect effects on water systems, ranging from people having too little water to wash their hands (which leads to diarrhoeal diseases), through to impacts on the economy, including agriculture – and within that plant and animal health.  These will in some regions lead to food insecurity. 

Climate change will have major impacts on human socio-economic development.  The main predictor of human health, both at country and individual levels, is human socio-economic development and wealth; if climate change slows or reverses economic development, health will suffer.  Impacts of climate change will be multigenerational, particularly in Africa and parts of Asia. 

Policy responses

There are broadly four areas where a policy response is needed to address the impact of climate change on human health. 

To start with, the healthcare industry and profession needs to reduce its own emissions as close to net zero as possible.  It is a significant contributor to climate change – not the biggest, but a significant one. 

Second, we must promote policies that have co-benefits, mitigating carbon emissions and improving health outcomes. 

Third, it will be necessary to find medical countermeasures against those diseases and conditions which will increase with climate change.  There is a responsibility, as part of our efforts at adaptation, to tackle these.  Science has a major role to play here. 

Finally, and this cannot be stressed too strongly, there must be honesty over trade-offs.  There is a tendency to try and wish them away.  Yet, that is not being honest and the result will be badly-designed and ineffective policies.  People need to be presented with both sides of the argument and make informed decisions.  Science has a major role in identifying trade-offs, and then in minimising them. 

There are many ways in which the issues surrounding healthcare and climate change can be addressed.  The following examples reference the UK, but the same is true in many other countries. 

Hospitals and clinics have to be warm (or cool) enough, because they have very vulnerable patients.  They also have to be well-ventilated, for reasons of infection and air pollution.  This all produces a tension, if at the same time there is an effort to reduce carbon emissions.  Opening windows while turning up the heating is not a good solution.

Healthcare produces very large numbers of disposables.  This was apparent during Covid, but it is a part of routine service.  That means a huge carbon footprint if these are aggregated globally.

The NHS transport fleet is one of the largest in the country, so what it does about its carbon emissions has a big impact on transport more generally. 

Then there are specialist areas; for example, some anaesthetic drugs are quite significant greenhouse gases in their own right. 

Policy options 

In terms of promoting policies with co-benefits, there are some clear wins.  The most obvious is the promotion of ‘active travel’, that is walking and cycling.  In almost every area of health, this will improve people's wellbeing – and of course it is reducing their use of cars.  In the 1950s, there were lots of people cycling, so we are just going back to something which was completely normal for our grandparents’ generation.

Installing loft insulation would be another policy with co-benefits.  It is a very good thing for elderly people as it reduces their bills and keeps them warmer.  Additionally, it reduces carbon emissions. 

Then, there are more nuanced items, including air pollution.  The switch to electric cars will lead to a reduction in tailpipe emissions, which is good for air pollution, there will be a reduction in particulate matters and NOx will be eliminated.  In addition, of course, it is good for carbon reduction.  It is not a complete answer but it takes us some of the way. 

However, there are some policies that create tensions. The switch from petrol to diesel, a deliberate policy decision by the Government, may have been good at the margin for carbon but it was bad for air pollution.  The two aims were not brought together under a single policy.

The use of renewable wood for space heating may be good from a carbon point of view but potentially will produce significant increases in particulate matter and air pollution.  It is a trade-off, we should be honest about that. 

Science and engineering

Science and engineering are hugely powerful in their ability to reduce – although not eliminate – health impacts.  As an example, Aedes mosquitoes, which are the vectors of several major diseases including dengue, Zika, chikungunya and Yellow Fever, are steadily moving north through Europe: climate change is contributing to that move.  There is a realistic possibility they will become established in the UK.  While it will not be possible to eradicate them, we can get rid of the associated diseases (there are already effective vaccines against Yellow Fever). 

Engineering solutions can reduce the health impact of, for example, heat stress and flooding.  In agriculture, drought- and flood-resistant crops are within the capability of science.

Being honest 

The worst way to make policy is to think that the policy goal does not come at a cost.  It is absolutely essential to identify the cost involved and to try and find a way to reduce the tension.  We must be honest about trade-offs and then seek as scientists to minimise them.  But if we do not tackle climate change, future generations will pay a heavy price in avoidable ill health.