Collaborative Research: Spatiotemporal Variability of Northwestern North American Temperatures in Response to Climatic Forcing

Lead PI: Dr. Rosanne D'Arrigo

Unit Affiliation: Biology and Paleo Environment, Lamont-Doherty Earth Observatory (LDEO)

May 2015 - April 2019
North America ; Gulf of Alaska ; Sukakpak, Alaska ; Northwestern Canada
Project Type: Research

DESCRIPTION: Generally, this award aims to apply a novel analytical technique to a millennial-scale tree-ring data from existing and newly-obtained sample archives to yield reconstructions of past temperature variability closely linked to dominant modes of climatic forcing, such as the Pacific Decadal Oscillation (PDO). The researchers are targeting three climatically-sensitive regions where tree-ring width (RW) records of this length are available in existing sample archives from the Gulf of Alaska in southern Alaska, Sukakpak in northern Alaska, and northwestern Canada (Yukon, British Columbia, Alberta). The resulting climate reconstructions will be compared with climate model outputs to examine spatiotemporal patterns in response to climate forcing (particularly volcanoes), identify uncertainties, and test hypotheses regarding internal and forced modes of variability.

This award will generate a suite of novel, maximum latewood density (MXD) chronologies for these sites using the Blue Intensity (BI) parameter, which is substantially less costly and labor intensive yet retains the accuracy and resolution of traditional MXD techniques. There are few sub-millennial to millennial scale MXD-based chronologies currently existing for this vast region. The researchers argue that the resulting BI chronologies, based on living and subfossil wood material, will yield robust records of past climatic extremes, trends and shifts in past temperature, spatiotemporal expressions of internal Pacific variability, as well as details regarding the external climate forcing over northwestern North America for the past millennium.

The research project has broad impact in four key aspects, namely:

First, this project will synthesize a network of climatically-sensitive tree-ring records from across northwestern North America to yield high-resolution, strongly calibrated reconstructions on past climate variability from intra-seasonal to Decadal to Centennial time scales. These dendroclimatic reconstructions will mainly be developed using existing data that will be processed to extract new information using the new BI technique, along with the development of field temperature reconstructions. Tree-ring data will be compared to model output and other proxy records and made available to the modeling community. This research will help advance a broader understanding of the long-term variability of climate over the past millennium for one of the most rapidly changing regions of the globe.

Second, scientific results from the project will be archived and provided to the scientific community through the National Geophysical Data Center (NGDC) and International Tree-Ring Data Bank (ITRDB).

Third, as appropriate, the researchers will engage with native groups in Alaska. In the past, the PIs have interacted extensively with northern communities by involving native peoples in research and plan to continue to do so for this project. The potential research outcomes could have relevance to native populations and the data and interpretations will be available to relevant communities (community groups, e.g. Arctic Borderlands Ecological Knowledge Cooperative,

Fourth, the project will support undergraduate and graduate students as part of the Woods Hole Oceanographic Institution Research Experience for Undergraduates (REU) program and the student program at The College of Wooster. The support of undergraduate students would allow for an early experience in research.