In Tucson, a city of 542,000 in the Sonoran Desert, extreme heat is a given. Two years ago, temperatures over 100 degrees lasted for 112 days.
“We crave shade here," writes Karen Mockler, and that’s why she’s joined other volunteer residents and city staffers working for an ambitious goal: planting one million trees planted by 2030. The digging part, she writes, turns out to be one tough job.