Could planting more trees save lives – and money – in the Twin Cities?

Air pollution and climate change pose an unparalleled health challenge going forward, could trees be the answer?
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City planners looking for ways to improve public health and protect the Twin Cities against climate change have been offered a simple solution: plant more trees.

A report by the Nature Conservancy called Planting Your Healthidentified Minneapolis as one of the world cities where a commitment to the original green energy can get a better return-on-investment than others around the globe.

In plain English, if the city invested in planting more trees, it would have greater health and pollution-reducing benefits than other, more expensive, public health and clean air ordinances.

Minneapolis was tied-second in the Nature Conservancy's rankings of where trees could be more beneficial, with the organization citing trees' ability to filter air pollution, absorb carbon dioxide, provide a cooling shade to people and buildings, and reduce air humidity.

"If you want healthier air, trees are part of that solution," Nature Conservancy scientist Rob McDonald said.

Why Minneapolis?

As we know, Minneapolis is a leafier city than most, and it might be surprising that a northern city would see the greatest benefit climate-wise from planting more trees compared to, say, the more humid cities of the south.

But as the report notes, these cities are already hot and will get hotter, but northern cities – with Detroit and Chicago also included – are not yet adapted to increasingly frequent summer heatwaves and high humidity, and as such it's these cities that could see the greatest benefit from planting more.

The Nature Conservancy claims that trees cool the air around them by 3.6 degrees on average, invaluable in the fight against heat-related deaths, which the World Health Organization estimates will rise from 12,000 a year now to 260,000 a year over the next 35 years.

The report also cites particulate matter (PM) – which can be generated by fossil fuels emitted from cars and household items like lawn mowers, as well as the burning of wood – as one of the major risks to urban public health going forward, with deaths from strokes and heart attacks linked to this air pollution predicted to increase by 30 percent by 2050.

Minneapolis and trees

As MPR reports, Minneapolis – much like many other cities – has been removing thousands of trees every year that have become diseased and storm damaged, with the park board estimating it's been removing 3,000 to 4,000 every 12 months, not including those taken down because they're infected with emerald ash borer.

It notes that the Nature Conservancy has planted 10 million trees in Minnesota in the past 10 years alone, but with most of those concentrated in the northeast of the state, the report has shone the light back on the need for urban forests.

The Star Tribune reports that Minneapolis plants twice as many as it takes down, but the growing risk of tree disease like the ash borer as well as Dutch Elm Disease – which is expected to kill 250,000 over the next 10 years – could make it difficult for the city to keep up, especially considering most of these are on private property.

"We are actively maintaining our existing canopy and trying to grow it slightly," Justin Long, assistant superintendent of the Minneapolis Park and Recreation Board, told the newspaper. "We don’t have a lot of resources to really grow the urban forest."

truggling to keep the forest canopies they have, much less add more.

“We are actively maintaining our existing canopy and trying to grow it slightly,” said Justin Long, an assistant superintendent of the Minneapolis Park and Recreation Board. “We don’t have a lot of resources to really grow the urban forest.”

This year the park board removed 5,000 trees and replanted twice that many, he said. And the city gives away 1,000 trees a year to homeowners through the Tree Trust, a nonprofit group.

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