The most recent assessment of climate impacts from the Intergovernmental Panel on Climate Change (IPCC) concluded with “very high confidence” that global warming “has adversely affected physical health of people globally”.
While action to stem the rise in global temperatures can help avoid these harms, it can also bring wider benefits to health and society in the near term.
The UK has committed to reduce its greenhouse gas emissions to net-zero by the middle of this century. To reach this target, the independent statutory Climate Change Committee (CCC) has suggested several realistic pathways under its sixth carbon budget to reach net-zero. These encompass different levels of emphasis on technological and behavioural change.
In our new study, published in Lancet Planetary Health, we quantify the potential impacts on mortality in England and Wales of climate change mitigation actions under two of these pathways. We focus on a number of different aspects of life – from air pollution and transport choices to energy efficiency and diets.
Our study is the first detailed national evaluation of the health effects of the CCC’s decarbonisation pathways. We show that net-zero is likely to lead to substantial benefits for public health – and that these benefits are greater with faster and more ambitious change.
How climate action can benefit people’s health
Seminal research, published in 2009, showed that actions to reduce greenhouse gas emissions are generally likely to be beneficial for health. (The work was led by some of my colleagues at LSHTM, including my inspirational friend and colleague Prof Paul Wilkinson, who sadly passed away in 2022.)
The benefits occur because climate action is typically accompanied by reductions in outdoor and household air pollution, better-insulated homes and increases in healthy behaviours – such as increased physical activity through more walking and cycling and greater consumption of plant-based diets.
In the time since that study was published, a large body of evidence has developed, based mainly on modelling studies, demonstrating significant benefits for health across different sectors.
In our new study, we focus specifically on the health impacts of net-zero for England and Wales. We look at six policy actions in the areas of electricity generation, transport, home energy, active travel and diets.
We concentrate on two of the pathways to net-zero set out by the CCC, comparing the “Balanced Pathway” of technological and behavioural measures (the CCC’s central and most likely pathway) and the “Widespread Engagement Pathway”, which assumes people make more substantial changes to their behaviours. The latter includes, for example, more radical decreases in red meat and dairy consumption than the central pathway.
We find that the CCC’s Balanced Pathway would lead to large health benefits due to reductions in outdoor and indoor air pollution exposure, improved home warmth during the winter, greater levels of walking and cycling and healthier, more plant-based diets.
The six actions we modelled in combination resulted in more than 2 million cumulative life years gained – where “life years” are the sum of all the years of life lived by the population – in England and Wales by 2050, and 11 million life years gained by the end of the century.
These benefits would be even greater under the Widespread Engagement Pathway – around 35% more by 2100. This is a result of a greater increase in physical activity (more than double that under the Balanced Pathway) and greater decrease in red meat consumption (50% vs 35% with the Balanced Pathway), with correspondingly larger changes in consumption of fruits, vegetables and legumes.
These findings suggest that policies promoting and enabling behaviour change would bring greater health benefits than technological solutions alone.
Which actions bring the biggest benefits for climate and health?
Of the separate actions we modelled, the greatest contribution to health improvement was from home energy efficiency measures, such as wall and loft insulation (over 800,000 life years gained by 2050), assuming that adequate ventilation requirements are met.
Reducing red meat consumption and increasing consumption of plant-based foods represented the next most effective action for reducing mortality (over 400,000 life years gained by 2050).
The top-left chart below shows the expected drop in red meat consumption under the Balanced Pathway (blue lines) and Widespread Engagement Pathway (red) by 2050 for males (circles) and females (triangles). The other three charts show the respective increases in consumption of fruits (top right), vegetables (bottom left) and legumes (bottom right).
Average daily consumption of red meat (top left), fruits (top right), vegetables (bottom left), and legumes (bottom right) in 2020-50 in England and Wales under scenarios corresponding to the CCC’s Balanced (blue) and Widespread Engagement (red) pathways for males (circles) and females (triangles). Source: Milner et al. (2023).
After diets, the next largest benefit comes from increased walking and cycling for travel, with around 125,000 and 287,000 life years saved by 2050 under the Balanced Pathway and the Widespread Engagement Pathway, respectively.
The charts below show the average number of kilometres per week travelled by walking (circles) and cycling (triangles) under the Balanced Pathway (blue lines) and Widespread Engagement Pathway (red) by 2050.
Average levels of walking (circles) and cycling (triangles) in km per week in 2020-50 in England and Wales under scenarios corresponding to the CCC’s Balanced (blue) and Widespread Engagement (red) pathways. Source: Milner et al. (2023).
Moving away from remaining coal for electricity, changing road traffic fuels and switching fuels for home energy, would also reduce mortality through reducing air pollution. Collectively, these three actions could add over 730,000 years to the overall lifespan of people in England and Wales by 2050 under the Balanced Pathway.
The left-hand chart below shows the expected drop in annual average levels of fine particulate air pollution (PM2.5) under the two CCC pathways, while the right-hand chart shows the decline for air pollution within homes.
Annual average ambient PM2.5 concentration (left) and annual average indoor PM2.5 concentration in homes (right) in 2020-50 in England and Wales under scenarios corresponding to the UK Climate Change Committee’s Balanced (blue) and Widespread Engagement (red) pathways. Source: Milner et al. (2023).
We note that switching to cleaner domestic fuels – primarily by replacing gas, solid fuels and biofuels with electricity and hydrogen – has a far greater impact on reducing air pollution levels than switching from coal-fuelled plants for electricity and switching road traffic fuels. This is because domestic combustion now represents a much greater proportion of the UK’s emissions of fine particles.
Are there any potential downsides?
It is clear that achieving net-zero greenhouse gas emissions will have substantial net-positive impacts through a range of policy actions, including decarbonising power generation, increasing home energy efficiency, promoting the use of cleaner vehicles, providing opportunities for active travel and adopting more sustainable diets.
As long as policies are designed and implemented with care, these actions should be “win-win” for the climate and health.
Some actions can, however, lead to unintended adverse consequences, which need to be considered and mitigated where possible. One example would be if home energy efficiency measures are installed without accompanying increases in home ventilation. This could mean home ventilation would be reduced and people’s exposure to pollutants generated within the home would increase with detrimental effects for their health.
Under such a scenario, our modelling suggests the effect of improving home energy efficiency could be negative overall for people’s health.
Other examples of possible adverse effects from actions to mitigate climate change include increased injury risk for pedestrians and cyclists, and the possibility of micronutrient deficiency following the adoption of more sustainable (plant-based) diets.
What needs to happen next in policy, research and practice?
The CCC’s pathways for achieving net-zero represent much-needed acceleration of action to reduce greenhouse gas emissions in the UK. In some areas – such as phasing out the use of coal for electricity – the UK has made considerable progress, but in other areas – such as decarbonising housing and the food system – there is still a long way to go.
Putting health at the centre of climate change mitigation policies would help to strengthen the argument for urgent and wide-scale action on climate change.
Although our modelling was specific to England and Wales, broadly similar findings would be expected in other high-income countries that enact equivalent climate policies.
Future research will need to consider how climate change mitigation policies might affect different groups in the population and contribute towards improving health inequalities in the UK and elsewhere. The benefits (and drawbacks) might not be experienced evenly – for example, eating more fruits and vegetables might be more difficult to achieve for poorer households.
Research will also need to move beyond modelling to study the effects of actual interventions. This will require more and better evaluations of actions already taken to understand whether we can observe the expected benefits of climate policies in the real world.
But we have enough evidence to show that reaching net-zero greenhouse gas emissions is likely to lead to substantial benefits for public health in England and Wales – and that these benefits are greater in a pathway that entails faster and more ambitious changes, especially in physical activity and diets.
Teaser photp credit: Wool.Life Wool Knops. Insulation Value of R-5.825 per cubic inch, or R-32 in a 2×6 stud wall. By Josephcathcart – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=106979410