Climate scientists funded in part by CPO’s Climate Observations and Monitoring (COM) program used tree ring data to create a new dataset of past temperatures. These data can be used to examine temperature dynamics and climate response in the Northern Hemisphere related to changes in Earth’s energy absorption (radiative forcing) over the last millennium. Published in the Journal of Climate, the study improves on prior spatial reconstructions using the same tree ring data and highlights regions such as the treeline in North America and eastern Siberia where the development of further long-term, temperature sensitive tree ring records would be beneficial.
Paleoclimatology is the study of past climates for which direct measurements and observations are not available. Temperature reconstructions based on paleoclimate data provide climate scientists an estimate of the surface temperatures in Earth’s distant past; in turn, these can reveal how Earth’s climate system responds to changes in radiative forcing. Paleoclimate reconstructions using tree ring data, for example, provide long-term records on the scale of one hundred years or more. This study used proxy data from the Northern Hemisphere Tree-Ring Network Development (NTREND), a database of 54 tree ring chronologies, to reconstruct May through August temperature anomalies from 750-1988 CE.
The study authors found a number of differences between their reconstruction and five existing paleo-temperature products’ response to volcanic eruptions and large climate transitions such as the Little Ice Age. According to the authors, the results of their study point to the need for a paleoclimate reconstruction intercomparison framework that examines the behavior, strengths, and weaknesses of different proxy networks and different reconstruction methods.