Question

5 lines on plant more trees

Answer 1

As researchers have discovered over the years, across dozens of studies, urban trees do at least two important things for public health:

1) They can soak up fine particle pollution from cars, power plants, and factories — an important job, given that particulates wreak havoc on human lungs and kill some 3.2 million people worldwide each year. The precise effect varies from city to city, but generally trees do improve air quality.

2) Urban trees can also cool down neighborhoods anywhere from 0.5 degrees Celsius to 2 degrees Celsius on the hottest summer days, which is vital during deadly heat waves. (Studies have found that every additional 1 degree Celsius in a heat wave leads to a 3 percent or more increase in mortality.)

The new Nature Conservancy report sifts through all this research and lays out some global scenarios. At the high end, a massive new tree-planting campaign in the world’s 245 largest cities, costing around $3.2 billion in all, could save between 11,000 and 36,000 lives per year worldwide from lower pollution. Those trees would also prevent between 200 and 700 heat-wave deaths per year — with that number presumably going up over time as global warming unfolds.

That’s not all: Because the trees would cool neighborhoods significantly, many households could end up using less energy for air-conditioning — reducing electricity use by between 0.9 and 4.8 percent in some cities and helping slow the pace of global warming. They can also retain storm water, boost real estate values, and may even have important mental-health benefits. Plus, they’d just look nice.