Large-scale data-model syntheses in paleoecology and paleoclimatology: The children of COHMAP

Background/Question/Methods

COHMAP (The Cooperative Holocene Mapping Project) was a groundbreaking effort to understand the drivers of the climate system over the last 20,000 years, a period spanning the last glacial maximum, the end-Pleistocene deglaciation, and the Holocene interglacial.  COHMAP was revolutionary with respect to both its scientific discoveries and through its establishment of large, coordinated teams of scientists, working across many facets of the earth system.  COHMAP scientists provided a unified understanding of how changes in the earth’s orbit could both affect high-latitude climate dynamics through changes in insolation and ice sheet extent while simultaneously governing the waxing and waning of the subtropical monsoons.   The initial development of COHMAP was led by Herb Wright, John Kutzbach, Tom Webb, and Ed Cushing at Minnesota, Wisconsin, and Brown, and quickly expanded to encompass dozens of scientists: climate modelers, paleoecologists, oceanographers, hydrologists, and other domains.  COHMAP both pioneered and benefitted from two advances in computing: supercomputers enabling the simulation of the climate system and the assembly of large datasets of many individual paleoecological and paleoclimatic records.  COHMAP’s focus was climatological, but it advanced ecology by showing how spatially complex climate changes (for well-understood reasons) could produce highly individualistic responses of species to climate change. 

Results/Conclusions

COHMAP culminated in 1993 with the publication of Global Climates since the Last Glacial Maximum, but its legacy lived as its scientists (and the many graduate students and postdocs involved in COHMAP) went on to start new synthetic research programs and careers.  Legacies include the NOAA World Data Center for Paleoclimatology, the BIOME 6000 mapping project, and the Paleoclimate Modeling Intercomparison Project.  Recently, PalEON (the PaleoEcological Observatory Network) has been launched with the mission of testing and improving the representation of ‘slow’ (decadal- to centennial-scale processes) in ecosystem models responding to a changing climate system.  Like COHMAP, PalEON is assembling interdisciplinary teams of ecosystem modelers, statisticians, and ecologists, unified by a common problem and the need to conduct science at the scale of the problem.  In this time, the key advances are in the area of data-assimilation, in which data and models can be fused to better estimate latent state variables (e.g. aboveground biomass; an unobservable quantity in the paleorecord) and improve model parameterization, and in the development of powerful new tools for research collaboration and data-sharing.