Christopher Williams

WORCESTER, Massachusetts — To curb the effects of climate change, private and public organizations across the world manage carbon projects to plant or restore forests, aiming to remove CO2 from the atmosphere. In turn they sell carbon credits to companies aiming to offset their greenhouse gas emissions. But the climate benefits of some carbon projects may be overestimated because they don’t account for changes in albedo — the percentage of sunlight that a forest reflects or absorbs, making it cooler or hotter — in their calculations, according to an Oct. 6 Nature Communications article co-authored by Geography Professor Christopher Williams of Clark’s School of Climate, Environment, and Society. “Nearly half of all reforestation credits issued in these projects would not have been issued if albedo had been used as a threshold for project siting and deducted for remaining projects, canceling about $8 billion of credits at an average price of $20 per tonne [a metric ton],” Williams says.