Lamont dendrochronologist Gordon Jacoby collected this sample of tree rings from a Siberian pine in Mongolia, which records the years 534-539 C.E. (left to right). The narrow, distorted rings for 536 and 537 indicate a drastic cooling in the northern hemisphere that froze sap in the cells during the growing season. Evidence for this abrupt climate change points to a massive eruption of the volcanic precursor of Krakatoa. Another theory invokes a cosmic impact that possibly triggered the eruption. Photo by Dee Breger

This five-year study will apply the science of tree-ring analysis (dendrochronology) and its application to the study of past climate to key questions regarding the processes that drive the development of the monsoon and its various characteristics through different regions.

“This is the single largest award for tree-ring research from the NSF and represents an aggressive investment in tree-ring research. The aim is to create opportunities that enhance creativity and provide for leaps in understanding of the monsoon,” says David Verardo, Director of the NSF’s Paleoclimate Program, which funded the project. “The science questions being asked are important, the region being studied is vital to understanding fundamental climate processes at the planetary scale, and the research team is top notch,” adds Verardo.

The Asian monsoon is one of the most important modes of natural climate variability on Earth, with differing regional impacts over areas extending from Africa to Australasia, northward into central Asia, and to the Pacific Ocean. Dozens of countries and nearly half the global population are affected by the climate variability it brings. Due to its considerable importance to global climate and implications for the world’s population, there is an urgent need for greater understanding of this system, with the ultimate goal being improved prediction on annual to decadal and longer time scales.

“The application of tree-ring analysis to climate studies is essential. Tree-ring records provide absolutely-dated, quantitative estimates of past climate on a year-by-year time scale.This allows us to reconstruct more complete records of variations and interrelationships between the components of the Asian monsoon system, and its impacts on related environments,” said Ed Cook, Doherty Senior Scholar, Lamont-Doherty Earth Observatory, and Principle Investigator for this study.

Analysis of tree ring data throughout ‘Monsoon Asia’ will enable scientists to reconstruct and analyze regional climate histories over timeframes of centuries to millennia. The data will also reveal information on three major process regions that collectively drive much of the variability of the Asian monsoon: 1) Asian land surface air temperatures, 2) sea surface temperatures in the Indian Ocean, and 3) tropical Pacific sea-surface temperatures associated with ENSO. Identifying interrelationships between these three major process regions, and how the Asian monsoon manifests itself in different regions across the globe, will lead to the development of improved models for better long-term forecasting. With approximately one half the world’s population impacted by the Asian monsoon, long-term forecasting will have profound social and economic impacts (e.g. long-term agricultural planning and improved risk assessment).

Scientists from the Tree-Ring Laboratory (TRL) are actively involved in pioneering research projects in many parts of the globe, from the high latitudes of both hemispheres to the low-latitude tropics of Asia and the Americas. Many of these studies have successfully developed and used tree-ring analyses to reconstruct and produce better understanding of both continental and oceanic climate variations.

Tree-Ring Reconstructions of Asian Monsoon Climate Dynamics is funded by The National Science Foundation and led by Drs. Edward R. Cook, Rosanne D. D’Arrigo, Brendan M. Buckley, and Gordon C. Jacoby, all of the Tree-Ring Laboratory, Lamont-Doherty Earth Observatory at Columbia University.

The Lamont-Doherty Earth Observatory, a member of The Earth Institute at Columbia University, is one of the world’s leading research centers examining the planet from its core to its atmosphere, across every continent and every ocean. From global climate change to earthquakes, volcanoes, environmental hazards and beyond, Observatory scientists provide the basic knowledge of Earth systems needed to inform the future health and habitability of our planet.

The Earth Institute at Columbia University is among the world’s leading academic centers for the integrated study of Earth, its environment, and society. The Earth Institute builds upon excellence in the core disciplines—earth sciences, biological sciences, engineering sciences, social sciences and health sciences—and stresses cross-disciplinary approaches to complex problems. Through its research training and global partnerships, it mobilizes science and technology to advance sustainable development, while placing special emphasis on the needs of the world’s poor.