Visiting CliSAP: Dr. Eugene Wahl


For six-plus weeks, guest researcher Dr. Eugene Wahl will be working with the CliSAP Research Area “Dynamics and Variability of the Climate System.” Dr. Wahl was born in San Diego, California and completed his Bachelor’s and Master’s in Economics at San Diego State University, USA. Afterwards, he received his PhD in Conservation Biology and Quaternary Paleoecology from the University of Minnesota, where he specialized in paleoclimate reconstruction over the Holocene. As a scientist working at the National Climatic Data Center, USA, he primarily works on reconstructing climate over the past one to two thousand years to help understand the natural climate variability on which human-driven climate change will be superimposed. He has done significant work on developing new reconstruction techniques, and during his stay he will support CliSAP in the field of mathematical paleoclimate methods. In the interview he talks about the fascination of paleoclimatology and what he hopes to contribute to CliSAP.

Guest researcher Dr. Eugene Wahl

CliSAP: How long have you been interested in climate research? And why does it fascinate you?

Dr. Wahl: I have been doing climate research since 1995. Paleoclimatology fascinates me because it has aspects like a “detective story,” where one tries to understand more about the climate system based on the “clues” that nature leaves behind in its processes. More formally, understanding past climates helps us understand the full nature of the climate system in terms of responses to different forcings and the potential for dynamics that are outside the experience of what we know or predate the time in which we’ve had instruments for measuring them.

CliSAP: What made you choose to visit Hamburg and the Cluster of Excellence CliSAP?

Dr. Wahl: To work with Dr. Eduardo Zorita and Dr. Sebastian Wagner on extending analog methods of “reconstructing” climate in Europe and North America earlier than has been done to date – back to 1500.

CliSAP: Not everybody at the Cluster of Excellence is familiar with paleoclimatology. Could you explain in layman’s terms what you want to work on while you are at CliSAP?

Dr. Wahl:
Understanding the climate of recent centuries. The idea is to do this by choosing continental-scale climate states, taken from climate model runs or from modern observations that are “re-analyzed” using weather model tools, that most closely conform with paleoclimate evidence. Paleoclimate evidence often provides information about just one variable, such as temperature or drought conditions, whereas the selected “analog” states from climate models and re-analyzed observations can provide complete climate fields across large regions for many variables, including pressure and winds.
CliSAP: Who are you working with at CliSAP, and where?

Dr. Wahl:  Drs. Eduardo Zorita and Sebastian Wagner, at the HZG in Geesthacht.

CliSAP: How will CliSAP benefit from your experience in the field of numerical simulation and mathematical models? And what will you take with you when you go back home?
Dr. Wahl: My expertise is in laboratory and mathematical paleoclimate methods, including the use of quantitative analog methods for reconstructing past climates. Dr. Zorita and Dr. Wagner are experts in climate modeling, and in analog reconstruction methods using climate model output. The combination of our skills makes the work we are doing possible, especially to reach farther back in time from current results, which only go back to 1850, and to include North America as well as Europe.
I will take with me a significantly improved capacity to reconstruct complete and consistent climate fields for multiple climate variables.

CliSAP: What is the goal of your trip?
Dr. Wahl:
Our goal is to reconstruct complete fields of surface temperature, surface pressure, 850hP geopotential height (pressure a little higher in the atmosphere), and precipitation (and possibly other variables) at monthly and seasonal time scales back to 1500 for much of Europe, and the same variables for summer (and possibly winter) for the temperate region of North America (between 30 to 50 N latitude) back to 1500.
CliSAP: Is there something else you want to say – maybe something important I didn’t ask you about?
Dr. Wahl: I'd like to say that I’m extremely grateful for the chance to participate in the CliSAP Cluster of Excellence, and that NOAA is also grateful for CliSAP’s support, allowing me to do this work with Drs. Zorita and Wagner.
Thanks for your effort and have a good time in Hamburg.

Dr. Wahl: You’re welcome!



Dr. Eugene Wahl
Helmholtz-Zentrum Geesthacht
Max-Planck-Str. 1
D-21502 Geesthacht