Mitigating climate change through afforestation: New cost estimates for the United States

We provide new cost estimates for carbon sequestration throughafforestation in the U.S. We extend existing studies of carbonsequestration costs in several important ways, while ensuring thetransparency of our approach. Our costs estimates have five dis-tinguishing features: (1) we estimate costs for each county in thecontiguous U.S., (2) we include afforestation of rangeland, in addi-tion to cropland and pasture, (3) our opportunity cost estimatesaccount for capitalized returns to future development (includingassociated option values) in addition to returns to agricultural pro-duction, (4) we develop a new set of forest establishment costs foreach county, and (5) we incorporate data on Holdridge life zonesto limit afforestation in locations where temperature and mois-ture availability prohibit forest growth. We find that at a carbonprice of $50/ton, approximately 200 million tons of carbon would besequestered annually through afforestation. At a price of $100/ton,an additional 100 million tons of carbon would be sequestered eachyear. Our estimates closely match those in earlier econometric stud-ies for relatively low carbon prices, but diverge at higher carbonprices. Our results indicate a smaller, but still important, role forforest-based carbon sequestration in offsetting U.S. greenhouse gasemissions.