The latest assessment of climate impacts by the Intergovernmental Panel on Climate Change (IPCC) concluded with “very high confidence” that global warming “has adversely affected human physical health globally”.
While action to stem the rise in global temperatures can help avoid these damages, it can also bring broader health and societal benefits in the short term.
The UK has committed to reducing its greenhouse gas emissions to net-zero by the middle of this century. To achieve this goal, the independent statutory Climate Change Committee (CCC) has proposed several realistic pathways under its sixth carbon budget to reach net zero. These include different levels of emphasis on technological and behavioral change.
In our new study, published in Lancet Planetary Health, we quantify the potential impacts on mortality in England and Wales of climate change measures under two of these pathways. We focus on a variety of 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 CCC’s decarbonization pathways. We show that net zero is likely to lead to substantial public health benefits – and that these benefits are greater with faster and more ambitious change.
How climate action can benefit human health
Basic research, published in 2009, showed that measures to reduce greenhouse gas emissions are generally likely to be beneficial to health. (The work was led by some of my colleagues at LSHTM, including my inspiring friend and colleague Prof Paul Wilkinson, who sadly died in 2022.)
The benefits arise because climate action is typically accompanied by reductions in outdoor and household air pollution, better insulated homes and increases in healthy behavior – such as increased physical activity through more walking and cycling and greater consumption of a plant-based diet.
In the time since this study was published, a large body of evidence has been developed, mainly based on modeling studies, showing significant health benefits 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 measures in the areas of electricity production, transport, energy for the home, active travel and diets.
We focus on two of the pathways to net zero set out by the CCC and compare the “Balanced Pathway” of technological and behavioral measures (the CCC’s central and most likely path) and the “Widespread Engagement Pathway” which assumes that people earn more significant changes in their behavior. The latter includes, for example, more radical decreases in the consumption of red meat and dairy products than the central path.
We find that the CCC’s Balanced Pathway would lead to major health benefits due to reductions in outdoor and indoor air pollution exposure, improved home heating in winter, greater levels of walking and cycling, and healthier, more plant-based diets.
The six actions we modeled in combination resulted in more than 2 million cumulative life years gained—where “life years” is the sum of all life years lived by the population—in England and Wales in 2050, and 11 million life years gained at the end of the century.
These benefits would be even greater under the Widespread Engagement Pathway – around 35% more in 2100. This is a result of a greater increase in physical activity (more than double that under the Balanced Pathway) and greater reductions in red meat consumption (50 % vs 35% with Balanced Pathway), with correspondingly greater changes in the consumption of fruit, vegetables and legumes.
These findings suggest that policies that promote and enable behavioral change will produce greater health benefits than technological solutions alone.
Which actions provide the greatest benefits for climate and health?
Of the separate actions we modelled, the largest contribution to health improvements was from home energy efficiency measures such as wall and ceiling insulation (over 800,000 life years gained in 2050), provided adequate ventilation requirements are met.
Reducing consumption of red meat and increasing consumption of plant-based foods represented the second most effective action in reducing mortality (over 400,000 life years gained in 2050).
The top left chart below shows the projected decline in red meat consumption under the Balanced Pathway (blue lines) and the Widespread Engagement Pathway (red) by 2050 for males (circles) and females (triangles). The other three charts show the respective increases in the consumption of fruit (top right), vegetables (bottom left) and legumes (bottom right).
After diets, the second largest benefit comes from increased walking and cycling for travel, with about 125,000 and 287,000 life-years saved in 2050 under the Balanced Pathway and the Widespread Engagement Pathway, respectively.
The charts below show the average number of kilometers per week traveled by walking (circles) and cycling (triangles) under the Balanced Pathway (blue lines) and the Widespread Engagement Pathway (red) in 2050.
Moving away from residual coal for electricity, switching fuels for road transport and switching fuels for home energy would also reduce mortality by reducing air pollution. Together, these three actions could add over 730,000 years to the total lifespan of people in England and Wales by 2050 under the Balanced Pathway.
The chart below on the left shows the expected decrease in annual average levels of fine particulate air pollution (PM2.5) under the two CCC pathways, while the chart on the right shows the decrease in residential air pollution.
We note that switching to cleaner household fuels – primarily by replacing gas, solid fuel and biofuels with electricity and hydrogen – is far more important in reducing air pollution levels than switching from coal-fired plants to electricity and switching fuels for road traffic. This is because domestic combustion now represents a much larger proportion of the UK’s fine particulate matter emissions.
Are there any potential downsides?
It is clear that achieving net-zero greenhouse gas emissions will have significant net-positive impacts through a range of policy measures, including decarbonising electricity generation, increasing energy efficiency in the home, promoting the use of cleaner vehicles, providing opportunities for active travel and adopting more sustainable diets.
As long as policies are designed and implemented carefully, these actions should be “win-win” for climate and health.
However, some actions may lead to unintended negative consequences that must be considered and mitigated where possible. An example would be if home energy efficiency measures are installed without accompanying increases in home ventilation. This could mean that home ventilation would be reduced and people’s exposure to pollutants generated in the home would increase with harmful effects on their health.
Under such a scenario, our modeling suggests that the effect of improving home energy efficiency may be generally negative for people’s health.
Other examples of possible negative effects of climate change mitigation measures include increased risk of injury to pedestrians and cyclists and the possibility of micronutrient deficiencies following the adoption of more sustainable (plant-based) diets.
What then needs to happen in politics, research and practice?
The CCC’s pathways to net zero represent much-needed acceleration of efforts 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 significant progress, but in others – such as decarbonising homes and the food system – there is still a long way to go.
Placing health at the center of climate change mitigation policies would help strengthen the case for rapid and comprehensive action against climate change.
Although our modeling was specific to England and Wales, broadly similar results would be expected in other high-income countries adopting similar climate policies.
Future research will need to consider how climate change mitigation policies might affect different groups in the population and help improve health inequalities in the UK and elsewhere. The advantages (and disadvantages) may not be experienced equally – for example, it may be more difficult for poorer households to eat more fruit and vegetables.
Research will also need to move beyond modeling 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 in England and Wales is likely to lead to significant public health benefits – and that these benefits are greater in a pathway that brings faster and more ambitious change, particularly in physical activity and diets.
Milner, J. et al. (2023) Impact on mortality of pathways to net zero greenhouse gas emissions in England and Wales: a multi-sectoral modeling study, The Lancet Planetary Health, doi:10.1016/S2542-5196(22)00310-2
Sharelines from this story