As scientists focus on city life with climate change fears, the environmental cost of the falling tree isn’t much touted. But it can be serious
America’s cities have lost nearly a third of their trees over the past 20 years, and as researchers pursue more sweeping strategies on climate change, the environmental cost of the trees being lost – 6m tonnes of carbon dioxide annually – isn’t being discussed often enough.
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The loss of forests, their leaves and fruit adds to pollution and carries risks to human health and the environment. Species and ecosystems are also dying off, and they had already been in decline when cities lost so many trees.
“Plants are central to ecosystem health and they help filter pollutants from the air and water,” said Trevor Sladden, a senior scientist at the Union of Concerned Scientists. “They also provide food and shelter for humans.”
What has been lost
More than 2m trees have been lost each year since 1993, according to a Union of Concerned Scientists analysis of US Department of Agriculture data.
A map showing the decline of American cities, by tree cover loss. Click on a city for an interactive version of the interactive map. Photograph: US department of agriculture
Some of the big cities where forests have been disappearing are Los Angeles, Boston, Atlanta, Seattle, New York and Chicago.
Source: US department of agriculture
A climate change simulation model that captures human, animal and plant impacts on trees and trees’ insects and fungi host plants. Photograph: ©All IPR
Why trees matter
Chunks of mountains and glaciers are being destroyed in Colorado. Water shortages are plaguing Lake Elsinore, California. Alaska is losing glaciers. Earth is warming and heatwaves are becoming more frequent. And some of the world’s most famous cities are coping with power cuts. In these, where lives are dependent on the electricity of the trees in front of them, local planners are increasingly considering the loss of trees as a hidden climate risk. The harm that happened in Detroit in March can be seen as a symptom of what can happen when that great green buffer of trees disappears. Photograph: Danita Delimont/Getty Images
Northwest forests have become highly depleted of saplings, small trees, fruit trees and trees on branches. All that yellow bark – as seen here in Covington, Maine – offers little defence against insects, disease and storms. Photograph: -/Reuters
Chicago itself lost more than 1m trees between 2015 and 2017 – the equivalent of five football fields a day. Photograph: Jannis Bell/AP