Collaborative Research: The North American Temperature Atlas--A Climate Field Reconstruction for Investigating Effects of Temperature on Past Droughts

The incidence of extreme heat events has increased in frequency and intensity in the last century as global temperatures have risen, driven by anthropogenic greenhouse gas forcing. When extreme heat occurs at the same time as drought, the impacts are exacerbated. These "hot drought" events have complex consequences for communities across North America, including altered water resource availability and fire regimes, as well as the magnitude of the uptake of carbon dioxide by forests. This project will compile new and previously collected temperature reconstruction data from tree cores from across North America into a "North American Temperature Atlas," which will allow for the analysis of relationship of heat and drought at a range of time and spatial scales. The goals of this project are to make new blue intensity measurements on previously collected tree cores from North America, compile existing blue intensity and maximum latewood density tree ring chronologies from North America, and combine the new and existing datasets together to create the “North American Temperature Atlas” (NATA), a gridded reconstruction of warm season surface air temperature. The NATA will be compared to a gridded North American drought atlas and a gridded North American seasonal precipitation atlas to determine the contribution of temperature to past droughts, evaluate the temperature-drought relationship, and place the modern occurrence of drought in the context of the last several centuries. The Broader Impacts are to create a web interface for public access to the NATA, support for graduate students at University of Tennessee, Knoxville, and University of Idaho, development of outreach to water and natural resource managers, creation of K-12 STEM activities for middle school students, tours of tree ring lab for K-12 students, mentoring high school and undergraduate students underrepresented in STEM on projects related to this work. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.