Dr. Ben Gaglioti (Lamont-Doherty Tree Ring Laband University of Alaska – Fairbanks) just published an article entitled: Timing and Potential Causes of 19th-Century Glacier Advances in Coastal Alaska Based on Tree-Ring Dating and Historical Accounts. Three of the coauthors include Wooster Earth Scientists and Tree Ring Labworkers, Josh Charlton (’19), Nick Wiesenberg (Department technician) and Dr. Wiles (Earth Sciences faculty). This contribution describes the Little Ice Glacier History of LaPerouse Glacier on the outer coast of Glacier Bay National Park and Preserve.
Dr Gaglioti did a great job putting together the glacial chronology for the site, and then coming up with some new ideas explaining why this glacier advanced to its Holocene maximum between CE 1850 and 1890. This was a time when it was not as cold as some other times within this broad interval (~ CE 1250-1850) we call the Little Ice Age. Dr. Gaglioti draws on some new and not-so-new proxy records that show a strengthening of the Aleutian Low over the past several 100 years and he suggests that the cooler summer temperatures aided by increased winter snowfall forced this glacier to its maximum extent. His methods and presentation in this paper are new and provide some excellent possibilities for future work by Wooster students. We look forward to continuing our collaboration with Dr. Gaglioti.
The photos below are from Dr. Gaglioti and show (top) the location of the glacier, (middle) the setting of the buried forest he discovered, and (bottom) what the amazing pristine trees look like as the ice retreats. Within this buried forest is also the first Alaskan Cedar paleo-forest that has been discovered. Here is a linkto a National Geographic sponsored blog describing some of the field work. Special thanks to Lauren Oakes for her excellent blog. The project was partially supported by the National Geographic Society, the Lamont-Doherty Earth Observatory and the National Science Foundation.
The Wooster Tree Ring Lab collaborated on a publication describing the recent thermal history of the Lidder Valley, Northwest Himalaya. Dr. Santosh Shah, the lead author, is a multitalented paleoclimatologist at the Birbal Sahni Institute of Palaeosciences in Locknow, India. He and his colleagues led the study that appeared in Climate Dynamics and is titled: A winter temperature reconstruction for the Lidder Valley, Kashmir, Northwest Himalaya based on tree-rings of Pinus wallichiana. Here is the abstract from the study:
Abstract: A regional, 175 year long, tree-ring width chronology (spanning 1840–2014 C.E.) was developed for Pinus wallichiana A. B. Jacks. (Himalayan Blue pine) from the Lidder Valley, Kashmir, Northwest Himalaya. Simple and seasonal correlation analysis (SEASCORR) with monthly climate records demonstrates a significant direct positive relationship of tree growth with winter temperature. A linear regression model explains 64% of the total variance of the winter temperature and is used to reconstruct December–March temperatures back to 1855 C.E. The most noticeable feature of the reconstruction is a marked warming trend beginning in the late twentieth century and persisting through the present. This reconstruction was compared with instrumental records and other proxy based local and regional temperature reconstructions and generally agrees with the tree-ring records and is consistent with the marked loss of glacial ice over the last few decades. Spectral analysis reveals a periodicity likely associated with the Atlantic Multidecadal Oscillation and El Niño–Southern Oscillation. Spatial cor- relation patterns of sea surface temperatures with the observed and reconstructed winter temperatures are consistent with larger scale warming in the region.
Map showing the location of the study in the Lidder Valley in Kashmir, Northwest India.
The rivers of the Lidder Valley are fed by glaciers from the Himalaya, which are becoming increasingly impacted by climate change and population pressures. The people within the valley depends on the water from the rivers and managing the water in this rapidly warming region is an increasing challenge. The results in this work show the increasing pace of the recent warming (see figure below).
Temperature reconstructions (above) based on tree-rings for the Himalaya. The curve on the top is from the new publication.
Dr. Shah is now working on using tree-rings to reconstruct river flow in the region. This is work that he presented last year at World Dendro in Bhutan and which we are are also collaborators. We are grateful to Dr . Shah for introducing us to climate change research in the Himalaya AND for his help to our former students of the Wooster Tree Ring Lab.
Jeff Gunderson, who recently completed his masters thesis at The Ohio State University in Geography used tree-rings from the Peruvian Andes to reconstruct climate. Jeff collaborated with Dr. Shah who shared his computer code and guidance in calibrating his Peruvian tree-ring records.
Jeff Gunderson, who recently completed his masters thesis at The Ohio State University in Geography used tree-rings from the Peruvian Andes to to tell us about past temperature changes in another region of the world that depends, in large part, on the melting glaciers for water. Jeff collaborated with Dr. Shah who shared his computer code and guidance in calibrating his tree-ring records.
A new article by researchers at the WTRL describing a bit about the history of tree-ring dating in Ohio is now out in
The Ohio Woodland Journal. A pdf can be found here.
The Wooster Tree Ring Lab is part of the international tree-ring community, that investigated the global extent and seasonal timing of the rapid increase in atmospheric 14C concentrations from the two largest cosmogenic events in 774 and 993 CE. The initiative named “COSMIC” is lead by Ulf Büntgen (Cambridge University), Lukas Wacker, and J. Diego Galván (Swiss Federal Research Institute WSL) and measured these two cosmogenic events in 44 of the world’s longest tree-ring chronologies. These events are now key marker years and a powerful dating tool. The study was published in Nature Communication and can be found here.
A recent publication that includes the Wooster Tree Ring Lab was published in Nature Communications. See this press release from Cambridge University who lead the effort.