Climate mitigation and the future of tropical landscapes
Land-use change to meet 21st-century demands for food, fuel, andfiber will depend on many interactive factors, including globalpolicies limiting anthropogenic climate change and realized improvementsin agricultural productivity. Climate-change mitigation policieswill alter the decision-making environment for land management,and changes in agricultural productivitywill influence cultivated landexpansion.We explore towhat extent future increases in agriculturalproductivity might offset conversion of tropical forest lands to croplands under a climate mitigation policy and a contrasting no-policyscenario in a global integrated assessmentmodel. TheGlobal ChangeAssessmentModel is applied here to simulate a mitigation policy thatstabilizes radiative forcingat 4.5Wm−2 (approximately 526 ppmCO2)in the year 2100 by introducing a price for all greenhouse gas emissions,including those from land use. These scenarios are simulatedwith several cases of future agricultural productivity growth ratesand the results downscaled to produce gridded maps of potentialland-use change. We find that tropical forests are preserved neartheir present-day extent, and bioenergy cropsemerge as an effectivemitigation option, only in cases in which a climate mitigation policythat includes an economic price for land-use emissions is in place, andin which agricultural productivity growth continues throughout thecentury.Wefind that idealized land-use emissions price assumptionsaremost effective at limitingdeforestation, evenwhen cropland areamust increase to meet future food demand. These findings emphasizethe importance of accounting for feedbacks from land-usechange emissions in global climate change mitigation strategies.