Presented by

Dr. Hanqin Tian
Solon & Martha Dixon Professor
Director of International Center for Climate and Global Change Research
School of Forestry and Wildfire Sciences
Auburn University

Abstract:

The terrestrial biosphere can release or absorb the greenhouse gases, carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), and therefore has an important role in regulating atmospheric composition and climate. Recent assessment (IPCC AR6) indicated that the land biosphere plays a major nature contribution to climate stability by removing around one third of anthropogenic CO2 emissions from the atmosphere each year. However, anthropogenic perturbation of the land biosphere has altered the carbon and nitrogen cycles, and the resulting increases in the emissions of non-CO2 greenhouse gases (CH4 and N2O) in particular can contribute to climate change. By considering all three major GHGs (CO2, CH4 and N2O ) together, our study shows that the cumulative warming capacity of concurrent biogenic CH4 and N2O is a factor of about two larger than the cooling effect resulting from the global land carbon dioxide uptake in the 2000s. Land-use intensification using today’s practices to meet food and energy demands increases anthropogenic GHG emissions, which is not consistent with stabilizing the climate at low temperature scenarios. However, the adoption of climate-smart land use practices to enhance carbon storage as well as reduce non-CO2 GHG emissions from human-impacted land ecosystems could reverse the biosphere’s current warming role. Therefore, how we manage the global lands needs to become a central part in our strategy to mitigate climate change.