Falmouth, Mass. – The impacts of land-cover change (for example, conversion of forest to cropland) on climate, are widely documented, but there have been few studies examining the impacts of land management on climate. Land management refers to variations in management within the same land-cover type, such as tilling or cropping practices. A new study co-authored by Woods Hole Research Center Acting Director, Richard A. Houghton, finds, as the title of the paper suggests, “Land management and land-cover change have impacts of similar magnitude on surface temperature.” The paper, published in Nature Climate Change recommends a full accounting of the actual cost to the climate system of different land management choices, whether for sustainable land management or climate change mitigation strategies.
According to Dr. Houghton, “Land-cover change, such as deforestation, is generally understood to add to climate change through the release of carbon dioxide to the atmosphere. The process affects the chemistry of the atmosphere. But both land-cover change and land management also have biophysical effects, altering the surface temperature through changes in reflectivity, evaporation, and turbulence.”
Roughly half of the Earth’s land surface no longer experiences land-cover change but is managed to satisfy human demands. Land management is expected to become more intense as the global population grows in coming decades, leading to greater competition for a limited supply of land. The high carbon costs of converting forests to agricultural lands, and the growing demands of food, feed, fiber and biofuels will lead to an intensification of agricultural lands.
This study looked at changes in biophysical properties due to changes in land management within a land-cover type. The team combined MODIS satellite observations of similar climate but different land-management changes with ground information from selected areas to examine changes in biophysical properties. The team confirmed that changes in management accounted for as much surface warming (through biophysical processes) as changes in land cover (through biochemical processes involving emissions of carbon dioxide). ”This is the first time that the biophysical effects of management have been shown to enhance the climatic effects of deforestation,” Dr. Houghton said.
Dr. Houghton’s work was made possible through support from NASA.
WHRC is an independent research institute where scientists investigate the causes and effects of climate change to identify and implement opportunities for conservation, restoration and economic development around the globe.