Mackenzie Delta, NW Canada 750 Year Summer Temperature Reconstruction Porter, T.J.; Pisaric, M.; Kokelj, S.; deMontigny, P. Porter, T.J. Pisaric, M. Kokelj, S. deMontigny, P. Air Temperature Reconstruction earth science/paleoclimate/climate reconstructions|tree ring (age,null,null,year Common Era,null,climate reconstructions|tree ring,null,null,N,null) earth science/paleoclimate/climate reconstructions|tree ring (minimum surface temperature,ring width,null,degree Celsius,Jun-Jul,climate reconstructions|tree ring,null,regression analysis,N,1 standard error = +/- 0.86 deg C; simple linear regression) earth science/paleoclimate/tree ring (tree ring standardized growth index,null,null,null,null,tree ring,composited,null,N,Regional divergence-free tree-ring chronology) earth science/paleoclimate/instrumental (minimum surface temperature,null,null,degree Celsius,Jun-Jul,instrumental,null,null,N,Environment Canada regional compilation of local instrumental records) earth science/paleoclimate/reconstructions (Mackenzie Delta>LATITUDE >LONGITUDE ) We present a reconstruction of June-July minimum temperatures since AD 1245 for the Mackenzie Delta region based on a 29-site network of white spruce (Picea glauca) ring-width series. Most but not all trees experienced a divergent temperature-growth response, similar to the divergence that has affected other white spruce trees across Yukon and Alaska. However, divergence in the study region began as early as AD 1900 and we have documented our methods to avoid including divergent signals in the reconstruction. Calibration/verification testing based on local temperature data, and multi-century coherence with nearby and large-scale temperature proxy records, confirm that our reconstruction is robust. The reconstruction shows cool conditions in the late 13th, early 18th and early 19th centuries, corresponding with solar minima and increased volcanism. These cool periods are interrupted by warm periods consistent with early to mid-20th century warmth. The late 20th century is the warmest interval, and the last decade is estimated to be 1.4C warmer than any decade before the mid-20th century. The reconstructed climate history corroborates other proxy-based inferences and supports the notion that high-latitude regions such as the Mackenzie Delta have experienced rapid warming in recent decades that is exceptional in the last eight centuries. STUDY NOTES: A ring-width-based reconstruction of Summer (June-July) minimum temperatures since AD 1245 from white spruce stands in the Mackenzie Delta region, northwestern Canada. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Porter, T.J. Investigator : Pisaric, M. Investigator : Kokelj, S. Investigator : deMontigny, P. 2016-10-28 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/20652 https://www1.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/northamerica/canada/mackenzie2013temp.txt https://www1.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/northamerica/canada/mackenzie2013temp.txt English https://www.ncdc.noaa.gov/paleo/study/20652 https://www1.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/northamerica/canada/mackenzie2013temp.txt Trevor J. Porter, Michael F.J. Pisaric, Steven V. Kokelj, Peter deMontigny2013A ring-width-based reconstruction of June-July minimum temperatures since AD 1245 from white spruce stands in the Mackenzie Delta region, northwestern CanadaQuaternary Research802167-17910.1016/j.yqres.2013.05.004http://www.sciencedirect.com/science/article/pii/S0033589413000525 START YEAR: 1245 AD * END YEAR: 2007 AD -135.52 68.12 -132.22 69.13