By Anders Lorenzen

We know that planting more trees is good for the planet and for tackling climate change. But a recently published study shines a light on the long term benefits of having more trees in cities. Thus you can both protect human health and take action on climate change by planting more trees.

We already know that trees in cities contribute to cooling and cleaning the air, and they also absorb greenhouse gases. These three effects are key elements in limiting the impacts of climate change and air pollution. But researchers at the Barcelona Institute for Global Health have found they also keep death at bay.

Mark Nieuwenhuijsen, director of the institute’s urban planning, environment and health initiative, said: “More green space is better for health. People actually live longer if there is more green space around.” The research conducted by the institute pulled data from nine other studies which involved more than eight million people in seven countries ranging from China to Canada. It was the largest study ever conducted on this issue according to the authors of the study.

Researchers used satellite images to determine the amount of vegetation (trees, grass and shrubs) within 500 metres of people’s homes. The levels of vegetation were then ranked under a system known as normalized difference vegetation index (NDVI).

For several weeks those involved in the study were tracked, and any premature deaths caused by health conditions such as heart or respiratory diseases were factored into the findings. The researchers subsequently found that in cities from Barcelona in Spain to Perth in Australia, a 10% increase in greenery led to an average 4% reduction in premature mortality.

The findings in this study, Nieuwenhuijsen believes, demonstrate that access to vegetation will benefit mental health, reduces stress, cut pollution and encourage physical activity. He stated: “What we need to do is increase green space in many cities … so that people can actually live a healthy life. A ‘nice green city’ would have between 20% and 30% of every area covered in vegetation”

The projections of the United Nations (UN) show that by 2050 two-thirds of the world’s population will live in urban areas. And, as a result, many city planners are actively looking at how to increase greenery while cities grow in extent and population. Researchers are also earmarking trees as one perfect solution to climate change mitigation, as they provide shade and lower temperatures during extreme heat events, and reduce the risks of flooding.

With the focus on the climate crisis, governments around the world are looking to tree planting as one solution to taking action on climate action. This research underlines that there are several problems that can be dealt with by simply planting a tree.