The world needs more trees. Chicago and Illinois must help.

On Tuesday, more than 100 world leaders vowed to halt deforestation over the next decade at the United Nations climate summit in Glasgow, Scotland. President Joe Biden pledged to work with Congress to spend $9 billion through 2030 to protect trees.

The Chicago region and Illinois need to do their part.

Planting and preserving trees takes carbon dioxide out of the air instead of letting it escape into the atmosphere, where it warms the planet. Chicago can help by doing more to protect its mature trees. Last year, it was reported Chicago lost an average of 10,000 more trees since 2010 than it has planted every year. The rest of the seven-county region has slightly better tree cover, but 36% of it is made up of invasive buckthorn trees, which are not good hosts for birds and other native fauna.

Besides absorbing carbon dioxide, trees cool areas that otherwise would be heat islands, where buildings and pavement reflect sometimes-intense heat. They help people with respiratory problems by filtering the air. They create habitat for wildlife and provide a welcome oasis for birds that migrate through the area in the spring and fall. Trees also soak up stormwater that otherwise might wind up in someone’s basement, an attribute that will be increasingly important as more and stronger storms — strengthened by a warming climate — move through the region.

And let’s face it, tree-lined streets make neighborhoods more pleasant.

To preserve our tree canopy, protect mature trees

Mayor Lori Lightfoot’s office has set aside $46 million for planting new trees — 75,000 around the city over the next five years — which is twice the number planted last year and a big step forward. But the city also needs to act to protect its mature trees, many of which are threatened by infection. To save money, the city in 2018 decided to stop inoculating ash trees against the invasive emerald ash borer and let the remaining 50,000 die off. Instead, the city should protect mature trees when possible because it takes so long for new ones to grow to their full size. New trees with two-inch diameter trunks won’t contribute meaningfully to the tree canopy for 20 or 30 years.

Inoculating trees isn’t cheap, and it has to be repeated every few years. Costs to do it city- wide are estimated at $2.7 million to at least $6 million. But the cost of cutting dead trees down isn’t cheap either. And every mature tree that is lost makes it that much harder to reverse the planet’s deforestation.

In the seven-county region outside Chicago, some suburbs such as Hazel Crest and Downers Grove have made a healthy tree canopy a priority. But some other communities don’t have urban foresters or any paid staff who attends to their trees. That is no way to nurture a healthy tree canopy.

Globally, according to Global Forest Watch, the world lost more than a billion acres of forest between 2001 and 2020, about half the size of the United States. Almost 64 million acres were lost just last year. Reversing that trend would be perhaps the most effective near-term step that can be taken to avoid the worst outcomes of climate change. The world’s leaders have not lived up to past promises to save trees.

Gov. J.B. Pritzker was one of seven governors, and the only one from the Midwest, who went to Glasgow, where he touted Illinois’ environmental initiatives. We urge him to find ways to improve the tree cover back home, which it can provide environmental benefits and slow down soil erosion.

Restoring trees once they are lost is not always easy. Iceland has been working for 100 years to revive forests chopped down a millennium ago but has managed to increase its tree cover only minimally, from less than 1% to about 1.5%.

The entire seven-county region needs to develop a strategic plan for an urban forest. It’s easy to criticize nations where deforestation runs amok. But we must do more than criticize.

It’s urgent that we protect and plant trees.

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