Our Changing Climate: The role of North American NOx Emissions Richard Damoah, Ph.D. Research Scientist GESTAR/USRA NASA Goddard Space Flight Center Greenbelt, MD [email protected] http://acdb-ext.gsfc.nasa.gov/People/Damoah/ According to the Intergovernmental Panel on Climate Change Fifth Assessment Report on climate change (IPCC AR5, 2013), many aspects of the climate system are showing evidence of a changing climate. With high confidence the report states that human activities have contributed and continue to contribute to our changing climate. Using some of these evidences and other studies this talk will focus on answering the following; (a) is our climate really changing? (b) Are we guilty of these changes? (c) What does the future holds for us? (d) How does NOx emissions contribute to climate change? And (e) what can we do to reduce NOx contributions to our changing climate? To answer the last two questions, a study to quantify the response of climate forcing to O3 and methane CH4 perturbations caused by a marginal increase (0.1 Tg N) in anthropogenic emissions of NOX in January and July from 21 (10o x 10o) geographical locations in North America was investigated. Changes in the perturbations have been calculated with a global chemistry-climate model. Addition of NOX emissions led to an initial increase in global O3 burdens up to 0.9 Tg and started to decay away after 4 months. Global CH4 burdens decreased (by increasing OH) up to -0.7 Tg and decay gradually after 6 months. Climate forcings resulting from the regional emission increases were calculated using an off-line radiative transfer model, accounting for the changes in both O3 and CH4. Our results show that O3 induced time-integrated radiative forcings show both positive (initial) and negative (long-term) phases. For the positive phase the time-integrated radiative forcing peaks at 0.454 mW m-2 years, however, for the negative phase the forcing peaks at -0.300 mW m-2 years. CH4 on the other hand show a single phase (negative) that peak at -1.302 mW m-2 years. The total net radiative forcings of CH4 term and the two O3 terms from all the 21 locations produced a net climate cooling effect (negative forcings) irrespective of the season of the emission pulses. Both the O3 and CH4 burdens and the associated radiative forcings depend strongly on the geographical location, the season as well as the altitude of the emission pulses. They are most sensitive to NOx emitted at aircraft altitude in summer from latitudes closer to the equator and least sensitive to emissions at the surface in winter from mid to high-latitude. BIO: Dr. Damoah received his PhD in Atmospheric Science from Technical University of Munich (TUM), Germany in 2005. After graduation he was awarded UK’s NERC (Natural Environmental Research Council) Postdoctoral Research Associate position at University of Edinburgh in UK. At Edinburgh he worked on climate modeling. Before joining NASA he was at University of Waterloo in Canada as a Research Fellow working on Air Pollution Transport to the Arctic. Currently, Dr. Damoah is a Research Scientist at NASA Goddard Space Flight Center (GSFC) in Greenbelt Maryland, with the USRA (Universities Space Research Association) working on Air Quality and Climate, and a part time faculty member in the Physics Department at Morgan State University.