That's what Chicago is doing, among other forward-thinking ideas:
Awareness of climate change has filled Chicago city planners with deep concern for the trees.
Not only are they beautiful, said Ms. Malec-McKenna, herself trained as a horticulturalist, but their shade also provides immediate relief to urban heat islands. Trees improve air quality by absorbing carbon dioxide, and their leaves can keep 20 percent of an average rain from hitting the pavement.
Chicago spends over $10 million a year planting roughly 2,200 trees. From 1991 to 2008, the city added so many that officials estimate tree cover increased to 17.6 percent from 11 percent. The goal is to exceed 23 percent this decade.
The problem is that for trees to reach their expected lifespan — up to 90 years — they have to be able to endure hotter conditions. Chicago has already changed from one growing zone to another in the last 30 years, and it expects to change several times again by 2070.
Knowing this, planners asked experts at the city’s botanical garden and Morton Arboretum to evaluate their planting list. They were told to remove six of the most common tree species.
Off came the ash trees that account for 17 percent of Chicago tree cover, or more than any other tree. Gone, too, are the enormous Norway maples, which provide the most amount of shade.
A warming climate will make them more susceptible to plagues like emerald ash disease. Already white oak, the state tree of Illinois, is on the decline and, like several species of conifer, is expected to be extinct from the region within decades.
So Chicago is turning to swamp white oaks and bald cypress. It is like the rest of adaptation strategy, Ms. Malec-McKenna explains: “A constant ongoing process to make sure we are as resilient as we can be in facing the future.”
Pretty radical stuff.
Kit Stolz 