Shade trees positioned near houses in Sacramento, Calif., such as those in this photo, can significantly affect electricity use. Tree cover on the west and south sides of Sacramento homes reduced average summertime electricity demand by more than 5 percent, according to a study by NIST and the USDA.

To mitigate climate change, Peru, one of the poorest countries with 30% population living under $2, 10% under $1 a day, planting 512,820 trees daily to capture more than 570,000 metric tons of carbon dioxide annually. Who’s next?

Dell is still finding it an uphill struggle to persuade its customers to take part in its "Plant a Tree for Me" scheme. Under this plan, customers can choose to spend an extra £1 per notebook or £3 per desktop to offset its estimated carbon emissions for the next three years.