SAMSI Paleo Family’s Secret to Staying Together for Many Years

The Paleo Family

The Paleo Family (minus one) (Left – Right): Martin Tingley, Liz Mannshardt, Bo Li, Peter Craigmile and Murali Haran.

Sometimes groups are meant to be. Take a working group that focuses on Paleoclimate data, who now affectionately calls itself the “Paleo Family.” This group started over five years ago at a program on Space-time Analysis for Environmental Mapping, Epidemiology and Climate Change at SAMSI’s opening workshop. Usually most groups dissipate after the research program is formally over, but some are still very active even several years later.

The group had started out as a larger group, but has whittled down to six people including former SAMSI postdocs Bala Rajaratnam, (now an Assistant Professor at Stanford University), Martin Tingley (now Assistant Professor at Penn State University), Elizabeth Mannshardt (now a Postdoc at North Carolina State University) and Murali Haran (Associate Professor at Penn State University) along with Bo Li (Associate Professor at University of Illinois at Urbana-Champaign) and Peter Craigmile (Associate Professor at The Ohio State University).

The group focused on the science of reconstructing past temperatures based on proxy records such as tree rings, lake sediments and ice cores. Modern instrumental records of weather only date back to about 1850, so proxies can help extend records to at least another 1,000 years.

The group has published “Piecing together the past statistical insights into paleoclimatic reconstructions,” in the 2013 Quatenary Science Reviews 35, 1-22; which is also referred to as the “monster paper,” by the group. This paper has been referenced in the Intergovernmental Panel on Climate Change (IPCC) report. This paper outlines the statistical challenges of using instruments and proxies to reconstruct past climate, in space and time, and lays out a flexible, Hierarchical framework for the reconstruction problem. Martin says, “Our goal was to demonstrate that more sophisticated statistical techniques allow the data to be used to address more scientifically interesting questions.”

Subsets of the group have published a number of relevant papers including, “Statistical modeling of extreme value behavior in North American tree-ring density series.” in the 2013 Climatic Change, 117, 843-858 and Tingley, Martin P. and Bo Li, comments on “Reconstructing the NH mean temperature: Can underestimation of trends and variability be avoided?” by Bo Christiansen. Journal of Climate 25: 3441-3446, 2012, and they have contributed to discussions of other paper. The group is in the middle of preparing another peer-reviewed paper. Martin says, “An important goal of paleoclimate science is to use the longer time frame afforded by the proxies to provide out-of-sample assessments of the climate models that are used to project future climate. We are building hierarchical statistical models to rank simulations of past climate based on their agreement with proxy-derived reconstructions.”

The “monster paper” was also used as the basis for a paleo climate seminar course at The Ohio State University (OSU) in 2012, “Statistical Methods: Paleoclimate Data and Models”. Martin and Peter gave lectures there, as well as Mark Berliner, professor of statistics at OSU and Jason Box, visiting scholar at the Byrd Polar Research Center and Professor at the Geologic Survey of Denmark and Greenland.

Bala Rajaratnam (L) and Elizabeth Mannshardt (R)

Bala Rajaratnam (L) and Elizabeth Mannshardt (R) recently visited SAMSI.

“I don’t think there had been something previously that laid out statistical considerations or methods when you are working with paleo data,” remarked Elizabeth.

Each person in the group comes from different research backgrounds so each person brings some unique skill to the group. Also, diversity is another thing that we are proud of the group. We come from six different countries across four different continents, so our discussions and research are the integration of strength from different cultures.

Martin helped set the agenda early on because he had the background working with paleoclimate data. Martin said, “This group has been an incredible opportunity and resource for me — five statisticians who are willing to learn enough science and teach me enough stats that together we make progress. I view my main responsibility as keeping the group engaged by hunting down interesting problems.”   The statisticians work in a range of fields from applied to methodology, and including theoretical statistics research.   Each brings different strengths and insights to the group. “Peter is the king of code. He programs faster than I can type!” said Elizabeth.

“The group has been very supportive to each other, even on other professional items such as helping each other out when someone is job hunting,” noted Bala. “It is also entertaining to see how long it takes six Ph.D.s to all get on Skype at the same time too,” quipped Elizabeth.

Our group formed a special session on paleoclimate at the Purdue Symposium in 2012. “I was thrilled to have my friends gathered in West Lafayette, and had discussions in person,” said Bo.

And what, exactly, is the secret to their success? “We picked a topic that was very interesting. We are all open-minded. We like to tease each other and everyone is fair game, and we even poke fun at ourselves. I think we really genuinely like each other,” said Bala.  “At the beginning of each semester, we all get together to figure out when we can carve out the one hour a week to meet with each other. We all still consider this very important”, said Elizabeth.

Thanks to a comment on a climate debate blog, the group has their rock band name: “Tingley and the Flamboyant (Professional) Statisticians!”