This project will support a synthesis spanning more than three decades of research, focused on tree-ring analyses of northern forests. The northern forest ecosystems of the great land masses of North America and Eurasia are highly sensitive indicators of the Earth's carbon cycle. Over the past decades, these forests have yielded valuable information on variation in boreal forest growth as well as climatic and environmental change for the past millennium. Two main products will result from this project. First, a comprehensive, widely-accessible monograph that will synthesize this extensive body of tree-ring analysis from northern forests related to global change studies. The monograph will examine the so-called 'divergence effect', which means figuring out how and why tree growth and temperature patterns are not lined up at many northern sites, in recent decades. Documenting the divergence effect is critical for identifying and understanding the implications of future climate change on tree growth. Second, a CD atlas will be produced based on compilation of long-term tree-ring data, descriptions and reconstructions. This CD product will be made available to researchers and students worldwide and will provide important perspectives regarding the state of the science and provide materials for development of school curricula. This synthesis provides insights into the scientific decision-making process and is relevant to policy makers concerned with global change and its impacts.
Rosanne D'Arrigo, Nicole Davi, Gordon Jacoby, Rob Wilson and Greg Wiles The investigators for this project generated a synthesis of their tree-ring records developed for far northern latitudinal treeline forests over the past several decades. Tree growth in such settings are very sensitive and limited by temperature. This data comprised raw ring width measurements from wood samples, as well as final time series or chronologies spanning the past thousand years. Also included in this synthesis was a series of tree-ring based reconstructions, which are extended records of past climate variability, in this case for annual temperatures over the past millennium. These data were submitted to the NOAA Paleoclimatology databank so that they can be accessed by the broader community. In addition, a monograph describing our northern tree-ring studies has now been published by the American Geophysical Union/Wiley Press. This monograph presents a written synthesis of this research by the Lamont-Doherty Earth Observatory's Tree-Ring Laboratory and its collaborators on forests around the circumpolar north, from Alaska and Canada to Eurasia and the Russian Far East. This study describes how inferred temperatures have varied over the past thousand years, during such notable climate intervals as the Medieval Climate Anomaly, the Little Ice Age and the recent period of anthropogenic warming. Outreach for this project included participation of a schoolteacher in tree-ring laboratory activities. Dr. Nicole Davi, mentored by Rosanne D'Arrigo, was a post-doctoral fellow who served as an investigator for this project. The investigators also participated in various educational activities, including teaching of an online course on climatic change and participating in Open House exhibitions for the public and greater community.
