Research, published in a special issue of the Lancet Planetary Health journal, looked at three scenarios: carrying on the current path, increasing efforts to achieve the Paris goals, and a more ambitious scenario, which put health at the heart of tackling climate change.
In the UK, implementing policies to meet international climate goals would save 98,420 lives a year by 2040 through better “flexitarian” diets, which involve less meat and more vegetables, legumes and fruit.
Meanwhile, 21,480 lives could be saved by people taking more exercise and 3,458 from reductions in air pollution.
If even more ambitious plans were put in place to make sure health was the focus of climate policy, 100,000 lives a year could be saved through dietary changes, with 50% adopting flexitarian diets and 50% going vegan.
A further 5,770 lives could be saved from cuts to air pollution and 38,440 from more active travel, with 75% of people walking or cycling over the course of a week, the modelling suggests.
Across nine countries, including the US, China and Brazil, implementing national climate plans which meet the Paris goals could save 5.8 million lives due to better diet, 1.2 million lives due to cleaner air, and 1.2 million lives due to increased exercise.
And putting explicit health objectives in their plans, known as nationally determined contributions or NDCs under the Paris accord, could lead to a further reduction of 462,000 deaths due to air pollution, 572,000 from diet, and 943,000 from physical inactivity a year by 2040.
The lead author, Ian Hamilton, executive director of the Lancet Countdown on Health and Climate Change, said: “Unlike the direct benefits of carbon mitigation which are ultimately long-term and understood in terms of damage limitation, the health co-benefits of ambitious climate policies have an immediate positive impact. Not only does delivering on Paris prevent millions dying prematurely each year, the quality of life for millions more will be improved through better health.