How planting trees can help address inequality and improve health

Having more urban trees could mean better mental health, longer lives, and better air quality for city dwellers.
Having more urban trees could mean better mental health, longer lives, and better air quality for city dwellers.
Image: Ignacio Brosa/Unsplash
  • Having more trees in urban areas of the US could have prevented up to 38,000 deaths over the last 20 years, according to a Boston University study.
  • NASA images were used in the research and in a separate study by Nature Conservancy that found lower-income US neighbourhoods have 15.2% less tree cover than richer areas.
  • The health benefits of urban trees include reducing the impact of air pollution and improving mental health.

Trees can save lives.

Many thousands of deaths could have been prevented by growing more trees and greenery in urban areas of the US over the past 20 years, according to a new study from Boston University.

The researchers used NASA images to examine differences in tree cover around various US cities. The satellite photos show how the amount of green vegetation has changed between 2000, 2010 and 2019.

The inequitable distribution of urban trees.
The inequitable distribution of urban trees.
Image: NASA

Trees can help people in urban areas live longer

Researchers calculated that the greenery around 35 US cities had grown by an average of 2.86% between 2000 and 2010, and then by another 11.11% between 2010 and 2019.

The team then looked at mortality data for people aged 65 and over. They estimated that increasing vegetation by an extra 0.1 units of their measure would have led to a 34,000-38,000 reduction in the number of deaths from all causes in 2000, 2010, and 2019.

More urban trees could mean longer lives for city residents.
More urban trees could mean longer lives for city residents.
Image: NASA

How do urban trees help human health?

The shade that trees provide cools the air and the ground in urban areas, NASA notes.

Cities can be hotter than rural areas because buildings, streets and other manmade infrastructure absorbs heat and then releases it back into the urban surroundings.

Trees can help combat this phenomenon, which is known as the “urban heat island effect”.

By reducing how much heat city dwellers have to live with, trees and greenery can help prevent heat-related deaths, the Boston researchers noted in their study, which is published in the journal Frontiers in Public Health.

When people live near parks or green spaces, it can also mean they have more exercise and leisure time, which in turn can reduce the risk of chronic diseases like obesity, the researchers add.

Satellite images show that areas with a fewer urban trees are hotter.
Satellite images show that areas with a fewer urban trees are hotter.
Image: NASA

Lower income areas have fewer trees

Of the 5,723 communities studied, 92% had 15.2% less tree cover in low-income areas. They were also 1.5°C hotter during the summer than higher-income neighbourhoods.

Nature and Climate

How is the World Economic Forum fighting the climate crisis?

The World Economic Forum’s Centre for Nature and Climate accelerates action on climate change and environmental sustainability, food systems, the circular economy and value chains, and the future of international development.

  • Through the Global Plastic Action Partnership, the Forum is bringing together government, business and civil society to shape a more sustainable world by eradicating plastic pollution.
  • Global companies are collaborating through the Forum’s 1t.org initiative to support 1 trillion trees by 2030, with over 30 companies having already committed to conserve, restore and grow more than 3.6 billion trees in over 60 countries.
  • Through a partnership with the US Special Presidential Envoy for Climate John Kerry and over 50 global businesses, the Forum is encouraging companies to join the First Movers Coalition and invest in innovative green technologies to enable net-zero emissions by 2050.
  • The Forum is bringing global leaders together to reduce the environmental impact of value chains and make the $4.5 trillion circular economy opportunity a reality. The African Circular Economy Alliance is funding circular economy entrepreneurs and circular economy activities in Rwanda, Nigeria and South Africa, while the Circular Electronics in China project is helping companies reduce and recycle 50% of e-waste by 2025.
  • Since launching in 2020, the Forum’s open innovation platform UpLink has welcomed over 40,000 users who are working on more than 30 challenges crowdsourcing solutions to the climate crisis.
  • More than 1000 partners from the private sector, government and civil society are working together through the 2030 Water Resources Group to ensure availability and sustainable management of water and sanitation for all by 2030. The group has facilitated close to $1 billion of financing for water-related programmes.

Contact us for more information on how to get involved.

The study, completed by environmental organization Nature Conservancy and published in the journal PLOS ONE, found that there are 62 million fewer trees in low-income US neighbourhoods compared with high-income areas.

Investing $17.6 billion in tree planting and natural regeneration is needed to rebalance this inequality, Nature Conservancy says. This would benefit 42 million people in low-income neighbourhoods, it adds.

Higher-income neighbourhoods in the US have more urban trees than lower-income neighbourhoods, environmental organization Nature Conservancy found.
Higher-income neighbourhoods in the US have more urban trees than lower-income neighbourhoods, environmental organization Nature Conservancy found.
Image: PLOS ONE

Urban trees improve air quality in cities

Trees can also protect people living in cities from pollution-related diseases, such as air and water pollution, says technology initiative the Centre for the Fourth Industrial Revolution (C4IR) India.

In a blog for the World Economic Forum on the benefits of urban trees, a C4IR specialist cites a study by the US Forest Service suggesting that covering 30% of all urban land with trees could prevent up to 400 premature deaths from air pollution every year.

Trees can protect people by capturing pollutants from the air and improving air quality, explains the Woodland Trust, a conservation charity in the United Kingdom.

Urban trees can also improve mental health. A study in Germany found that living within 100 metres of a tree can reduce the need for antidepressant drugs. And doctors in Scotland were authorized to prescribe nature to their patients in a pioneering initiative.

With urban greening initiatives being introduced in cities and urban areas around the world – including Paris, Madrid, Seoul and Singapore – NASA’s satellite images should become even more tree-filled over the next decade.

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