Estimation of North American Methane Fluxes Using Space-borne Observations
Alexander Turner, Harvard University
Atmospheric methane is a strong contributor to greenhouse radiative forcing of climate, amounting to half of the radiative forcing from CO2 since pre-industrial times. It is emitted by diverse sources that are not well quantified. Recent advancements in space-borne observations have improved our ability to measure atmospheric methane, yet these measurements are subject to substantial biases and uncertainties (relative to sub-orbital observing systems). Here we show that observations from the most advanced space-borne short-wave infrared (SWIR) instrument, aboard the Greenhouse gases Observing SATellite (GOSAT), can be used to constrain North American methane sources at an effective 50 km resolution. GOSAT observations indicate that U.S. methane emissions are to a factor of 1.4 larger than the current bottom-up inventories suggest. We find a U.S. methane inventory of 44.5 ± 1.6 Tg (CH4) per year with 29 percent from livestock, 19 percent from wetlands, 17 percent from oil/gas, 17 percent from landfills, and 13 percent from coal. This implies a greater potential for methane controls to address climate policy objectives than is generally recognized.
Abstract Author(s): Alexander J. Turner, Daniel J. Jacob