2012 Articles

Proxy-to-proxy calibration: Increasing the temporal resolution of quantitative climate reconstructions

Gunten, Lucien von; D'Andrea, William Joseph; Bradley, Raymond S.; Huang, Yongsong

High-resolution paleoclimate reconstructions are often restricted by the difficulties of sampling geologic archives in great detail and the analytical costs of processing large numbers of samples. Using sediments from Lake Braya Sø, Greenland, we introduce a new method that provides a quantitative high-resolution paleoclimate record by combining measurements of the alkenone unsaturation index (UK 37) with non-destructive scanning reflectance spectroscopic measurements in the visible range (VIS-RS). The proxy-to-proxy (PTP) method exploits two distinct calibrations: the in situ calibration of UK 37 to lake water temperature and the calibration of scanning VIS-RS data to down core UK 37 data. Using this approach, we produced a quantitative temperature record that is longer and has 5 times higher sampling resolution than the original UK 37 time series, thereby allowing detection of temperature variability in frequency bands characteristic of the AMO over the past 7,000 years.