Raymond G. Najjar, Jr.

Raymond G. Najjar, Jr.

  • Professor of Oceanography
  • Joint Appointment with the Department of Geosciences
522 Walker Building
University Park, PA 16802
Email: rgn1@psu.edu
Phone: (814) 863-1586


  1. B.E., Mechanical Engineering, The Cooper Union for the Advancement of Art & Science, 1985
  2. Ph.D., Atmosphere and Ocean Science, Princeton University, 1990
  3. Post-Doctoral Scholar, National Center for Atmospheric Research, 1990–1993


Seeking a field where I could apply my love of math and science, I chose an engineering major in college. Studying fluid mechanics as a mechanical engineering major was an epiphany to me, but at the same time I became increasingly interested in the environment, inspired in no small part by brilliant science communicators like Rachel Carson, David Attenborough, and Carl Sagan. I made a lucky guess that graduate study in oceanography and atmospheric science would be a perfect marriage of my interests. My early research focused on large-scale, open-ocean biogeochemistry, particularly the cycling of nutrients (nitrogen, phosphorus, and silicon), oxygen, and carbon. A few years after arriving at Penn State in 1993, I became interested in coastal issues, such as eutrophication, hypoxia, and sea-level rise. I worked on numerous regional climate impact assessments, including one that was part of the first National Climate Assessment. I am mainly a data analyst, but I also use numerical models and remote sensing. Occasionally, I am lucky enough to go to sea, and have conducted studies in the Sargasso Sea and coastal waters of Antarctica and the Eastern United States. I've received funding for my research from the Environmental Protection Agency, the National Oceanic and Atmospheric Administration, the National Aeronautics and Space Administration, the National Science Foundation, the Pennsylvania Department of Environmental Protection, and Pennsylvania Sea Grant.

Stance and public engagement on climate change:

Humans are massively and rapidly transforming the climate. The overwhelming majority of the impacts are negative and will get worse. For example, coral reefs, one of the most important and wondrous ecosystems on Earth, are poised for permanent demise as a result of overheating and acidification. If we do not act quickly and aggressively to reduce greenhouse gas emissions or remove carbon dioxide from the atmosphere, we will be leaving a planet to our children and grandchildren that is a shadow of its former self. While our knowledge of the climate system is not perfect (and never will be), we know enough to act. Fossil fuels have served society very well but they have outlived their usefulness. Much safer forms of energy from the wind and sun should be deployed on a massive scale to save the planet from catastrophe.

I am available to give public presentations on climate change within an hour's drive from State College, PA or via webinar. Here are some presentations I have given:

Managing the threats of climate change in Pennsylvania. Mifflin County Public Library, Lewistown, PA. November 12, 2019. PDF PPT

Regional climate change impacts: What science tells us. The p4 Pittsburgh Climate Action Summit, Pittsburgh, PA. October 30, 2019. PDF PPT

Global warming as an opportunity. Cheryl Beth Silverman Memorial Lecture, The Academy of Natural Sciences of Drexel University. Phildadelphia, PA. May 8, 2019. PDF PPT

What climate change means for Chesapeake Bay restoration. St. Andrew’s Church Adult Forum, State College, PA. February 24, 2019. PDF PPT

Climate impacts on Pennsylvania. Citizens Climate Lobby Regional Conference Symposium, Philadelphia, PA. February 18, 2017. PDF PPT

Turning back the Crimson Tide: How to manage the unavoidable and avoid the unmanageable as Pennsylvania’s climate starts to look like Alabama’s. University Club Fireside Chat, State College, PA. May 17, 2016. PDF PPT

Five actions on climate change. Meeting of Good Shepherd Catholic Church Environmental Committee, State College, PA. January 24, 2016. PDF PPT

Courses taught:

  • Marine Biogeochemistry (Geosc 410)
  • Introductory Meteorology (Meteo 003)
  • Fundamentals of Atmospheric Science (Meteo 300)
  • Atmospheric Dynamics (Meteo 421)
  • Introduction to Physical Oceanography (Meteo 451)
  • Geophysical Fluid Dynamics (Meteo 520)
  • Physical Oceanography (Meteo 551)
  • Communication of Research in Atmospheric Science (Meteo 880)

Selected publications:

Click here for full publication list. All publications are available upon request.

Cavallaro, N., Shrestha, G., Birdsey, R., Mayes, M.A., Najjar, R.G., Reed, S.C., Romero-Lankao, P., Zhu, Z. (Editors), 2018. Second State of the Carbon Cycle Report (SOCCR2): A Sustained Assessment Report. U.S. Global Change Research Program, Washington, DC, USA, 878 pp.

Najjar, R.G., Herrmann, M., Alexander, R., Boyer, E.W., Burdige, D.J., Butman, D., Cai, W.-J., Canuel, E.A., Chen, R.F., Friedrichs, M.A.M., Feagin, R.A., Griffith, P.C., Hinson, A.L., Holmquist, J.R., Hu, X., Kemp, W.M., Kroeger, K.D., Mannino, A., McCallister, S.L., McGillis, W.R., Mulholland, M.R., Pilskaln, C.H., Salisbury, J., Signorini, S.R., St-Laurent, P., Tian, H., Tzortziou, M., Vlahos, P., Wang, Z.A., Zimmerman, R.C., 2018. Carbon budget of tidal wetlands, estuaries, and shelf waters of Eastern North America. Global Biogeochemical Cycles 32, 389–416.

Bannon, P.R., Najjar, R.G., 2018. Heat-engine and entropy-production analyses of the world ocean. Journal of Geophysical Research: Oceans 123, 8532–8547.

St-Laurent, P., Friedrichs, M.A.M., Najjar, R.G., Herrmann, M., Miller, S., Martins, D., Wilkin, J., 2017. Impacts of atmospheric nitrogen deposition on surface waters of the Western North Atlantic mitigated by multiple feedbacks. Journal of Geophysical Research: Oceans 122, 8406–8426.

Ross, A.C., Najjar, R.G., Li, M., Lee, S.B., Zhang, F., Liu, W., 2017. Fingerprints of sea-level rise on changing tides in the Chesapeake and Delaware Bays. Journal of Geophysical Research: Oceans 122, 8102–8125.

Walker, A., Titley, D.W., Mann, M.E., Najjar, R.G., Miller, S.K., 2018. A fiscally based scale for tropical cyclone storm surge. Weather and Forecasting 33, 1709–1723.

Seidensticker, L., Najjar, R.G., Herrmann, M., Boyer, J.N., Briceño, H.O., Kemp, W.M., Tomaso, D., 2018. Seasonal and interannual variability in net ecosystem production of a subtropical coastal lagoon inferred from monthly oxygen surveys. Estuaries and Coasts.

Schulte, J., Najjar, R.G., Li, M., 2016. The influence of climate modes on streamflow in the Mid-Atlantic Region of the United States. Journal of Hydrology: Regional Studies 5, 80–99.

Mannino, A., Signorini, S.R., Novak, M.G., Wilkin, J., Friedrichs, M.A.M., Najjar, R.G., 2016. Dissolved organic carbon fluxes in the Middle Atlantic Bight: An integrated approach based on satellite data and ocean model products. Journal of Geophysical Research: Biogeosciences 121, 312–336.

Tomaso, D., Najjar, R., 2015. Long-term variations in the dissolved oxygen budget of an urbanized tidal river: The Upper Delaware Estuary. Journal of Geophysical Research: Biogeosciences 120, 1027–1045.

Herrmann, M., Najjar, R.G., Kemp, W.M., McCallister, S.L., Alexander, R.B., Cai, W.-J., Griffith, P., Smith, R.A., 2015. Net ecosystem production and organic carbon balance of U.S. East Coast estuaries. Global Biogeochemical Cycles, 29, 96–111.

Schulte, J., Duffy, C., Najjar, R.G., 2015. Geometric and topological approaches to significance testing in wavelet analysis. Nonlinear Processes in Geophysics, 22, 139–156.

Ross, A.C., Najjar, R.G., Li, M., Mann, M.E., Ford, S.E., Katz, B., 2015. Sea-level rise and other influences on decadal-scale variations of salinity in a coastal plain estuary. Estuarine Coastal and Shelf Science, 157, 79–92.

Bannon, P.R., Najjar, R.G., 2014. Available energy of the world ocean. Journal of Marine Research, 72, 219–242.

Kim, T.W., Najjar, R.G., Lee, K., 2014. Influence of precipitation events on phytoplankton biomass in coastal waters of the eastern United States. Global Biogeochemical Cycles 28, doi:10.1002/2013GB004712, 1–13.

Signorini, S., Mannino, A., Friedrichs, M.A.M., Najjar, R.G., Cai, W.-J., Salisbury, J.E., Wang, Z.A., Thomas, H., Shadwick, E., 2013. Surface ocean pCO2 seasonality and sea-air CO2 flux estimates for the North American east coast. Journal of Geophysical Research, 118, 5439–5460.

Kim, T.-W., Lee, K., Najjar, R.G., Jeong, H.-D., Jeong, H.J., 2011. Increasing N abundance in the Northwestern Pacific Ocean due to atmospheric nitrogen deposition. Science, 334, 505–509.

Najjar, R. G., C. R. Pyke, M. B. Adams, D. Breitburg, M. Kemp, C. Hershner, R. Howarth, M. Mulholland, M. Paolisso, D. Secor, K. Sellner, D. Wardrop, and R. Wood. 2010.  Potential climate-change impacts on the Chesapeake Bay. Estuarine, Coastal, and Shelf Science, 86, 1–20.

Najjar, R. G., L. Patterson and S. Graham. 2009. Climate simulations of major estuarine watersheds in the Mid-Atlantic region of the United States. Climatic Change, 95, 139–168.

Hilton, T. H., R. G. Najjar, L. Zhong, and M Li. 2008. Is there a signal of sea-level rise in Chesapeake Bay salinity? Journal of Geophysical Research, 113, C09002, doi: 10.1029/2007JC00427.

Bailey, K. E., D. A. Toole, B. Blomquist, R. G. Najjar, B. Huebert, D. J. Kieber, R. P. Kiene, P. Matrai, G. R. Westby, and D. A. del Valle. 2008. Dimethylsulfide production in Sargasso Sea eddies. Deep-Sea Research II, 55, 1491–1504.

Zafiriou, O. C., H. Xie, N. B. Nelson, and R. G. Najjar. 2008. Carbon monoxide distributions reveal upper-ocean diel- and seasonal-scale photochemistry, biogeochemistry and mixing. Limnology and Oceanography, 53, 835–850.

Najjar, R. G., and 22 others. 2007. Impact of circulation on export production, dissolved organic matter and dissolved oxygen in the ocean: Results from Phase II of the Ocean Carbon-cycle Model Intercomparison Project (OCMIP-2), Global Biogeochemical Cycles, 21, GB3007, doi:10.1029/2006GB00285.