Journal cover Journal topic
Climate of the Past An interactive open-access journal of the European Geosciences Union
doi:10.5194/cpd-4-741-2008
© Author(s) 2008. This work is distributed
under the Creative Commons Attribution 3.0 License.
 
11 Jun 2008
Review status
A revision of this discussion paper for further review has not been submitted.
Eliminating the "divergence problem" at Alaska's northern treeline
M. Wilmking and J. Singh Institute of Botany and Landscape Ecology, Grimmer Strasse 88, Greifswald University, 17487 Greifswald, Germany
Abstract. Recently, an increasing off-set between tree-ring based temperature reconstructions and measured temperatures at high latitudes has been reported, the so called "divergence problem" (here "divergence effect"). This "divergence effect" seriously questions the validity of tree-ring based climate reconstructions, since it seems to violate the assumption of a stable response of trees to changing climate over time. In this study we eliminated the "divergence effect" in northern Alaska by careful selection of individual trees with consistently significant positive relationships with climate (17% of sample) and successfully attempted a divergence-free climate reconstruction using this sub-set. However, the majority of trees (83%) did not adhere to the uniformitarian principle as usually applied in dendroclimatology. Our results thus support the notion, that factors acting on an individual tree basis are the primary causes for the "divergence effect" (at least in northern Alaska). Neither different detrending methods nor factors acting on larger scales such as global dimming or an increase in UV-B radiation could explain our results. Our results also highlight the necessity to adapt the methods of paleoreconstruction using tree rings to account for non-stable climate growth relationships as these are found in the vast majority of sampled trees and seem to be the norm rather than the exception.

Citation: Wilmking, M. and Singh, J.: Eliminating the "divergence problem" at Alaska's northern treeline, Clim. Past Discuss., 4, 741-759, doi:10.5194/cpd-4-741-2008, 2008.
M. Wilmking and J. Singh
M. Wilmking and J. Singh

Viewed

Total article views: 3,988 (including HTML, PDF, and XML)

HTML PDF XML Total BibTeX EndNote
629 3,311 48 3,988 37 51

Views and downloads (calculated since 01 Feb 2013)

Cumulative views and downloads (calculated since 01 Feb 2013)

Saved

Discussed

Latest update: 28 Apr 2017
Publications Copernicus
Download
Share