Lake Silvaplana, Switzerland 765 Year Summer Temperature Reconstruction Trachsel, M.; Grosjean, M.; Larocque-Tobler, I.; Schwikowski, M.; Blass, A.; Sturm, M. Trachsel, M. Grosjean, M. Larocque-Tobler, I. Schwikowski, M. Blass, A. Sturm, M. Air Temperature Reconstruction Medieval Climate Anomaly (MCA) earth science/paleoclimate/climate reconstructions|insect|paleolimnology (surface temperature,midge assemblage,null,degree Celsius,Jun-Aug,climate reconstructions|insect|paleolimnology,filtered,null,N,9-100 year band pass filtered; based on chironomids and biogenic silica) earth science/paleoclimate/climate reconstructions|insect|paleolimnology (surface temperature,midge assemblage,null,degree Celsius,Jun-Aug,climate reconstructions|insect|paleolimnology,anomalized|filtered,null,N,9-100 year band pass filtered; anomalized with respect to 1961-1990 AD; based on chironomids and biogenic silica) earth science/paleoclimate/climate reconstructions|insect|paleolimnology (age,null,null,year Common Era,null,climate reconstructions|insect|paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology earth science/paleoclimate/paleolimnology earth science/paleoclimate/paleolimnology (Lake Silvaplana>LATITUDE 46.45>LONGITUDE 9.8) High-resolution quantitative temperature records are needed for placing the recent warming into the context of long-term natural climate variability. In this study we present a quantitative high-resolution (9-year) summer (June-August) temperature reconstruction back to AD 1177 for the south-eastern Swiss Alps. This region is a good predictor for summer temperatures in large parts of western and central Europe. Our reconstruction is based on a combination of the high-frequency component of annually resolved biogenic silica (bSi flux) data and the low-frequency component of decadal chironomid-inferred temperatures from annually laminated well dated sediments (varves) from proglacial Lake Silvaplana, eastern Swiss Alps. For the calibration (period AD 1760-1949) we assess systematically the effects of six different regression methods (Type I regressions: Inverse Regression IR, Inverse Prediction IP, Generalised Least Squares GLS; Type II regressions: Major Axis MA, Ranged Major Axis RMA and Standard Major Axis SMA) with regard to the predicted amplitude and the calibration statistics such as root-mean-square error of prediction (RMSEP), reduction of error (RE) and coefficient of efficiency (CE). We found a trade-off in the regression model choice between a good representation of the amplitude and good calibration statistics. The band-pass filtered bSi flux record is in close agreement both in the structure and the amplitude with two fully independent reconstructions spanning back to AD 1500 and AD 1177, respectively. All known pulses of negative volcanic forcing are represented as cold anomalies in the bSi flux record. Volcanic pulses combined with low solar activity (Spörer and Maunder Minimum) are seen as particularly cold episodes around AD 1460 and AD 1690. The combined chironomid and bSi flux temperature record (RMSEP = 0.57°C) is in good agreement with the glacier history of the Alps. The warmest (AD 1190) and coldest decades (17th century; 1680-1700) of our reconstruction coincide with the largest anomalies in the Alpine tree-ring based reconstruction; both records show in the decadal variability an amplitude of 2.8°C between AD 1180 and 1950, which is substantially higher than the amplitude of hemispheric reconstructions. Our record suggests that the current decade is slightly warmer than the warmest decade in the pre-industrial time of the past 800 years. STUDY NOTES: 765 year summer (JJA) temperature reconstruction for the Swiss Alps based on biogenic silica and chironomids from Lake Silvaplana, Switzerland. Lake Silvaplana, Switzerland: 46°27'N, 9°48'E, 1800m NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Trachsel, M. Investigator : Grosjean, M. Investigator : Larocque-Tobler, I. Investigator : Schwikowski, M. Investigator : Blass, A. Investigator : Sturm, M. 2012-06-13 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/13015 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/switzerland/silvaplana2010b.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/switzerland/silvaplana2010b.xls https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/switzerland/silvaplana2010b.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/switzerland/silvaplana2010b.xls English https://www.ncdc.noaa.gov/paleo/study/13015 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/switzerland/silvaplana2010b.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/switzerland/silvaplana2010b.xls Trachsel, M., M. Grosjean, I. Larocque-Tobler, M. Schwikowski, A. Blass, and M. Sturm. 2010. Quantitative summer temperature reconstruction derived from a combined biogenic Si and chironomid record from varved sediments of Lake Silvaplana(south-eastern Swiss Alps) back to AD 1177. Quaternary Science Reviews, Vol. 29, pp. 2719-2730. doi:10.1016/j.quascirev.2010.06.026 START YEAR: 1181 AD * END YEAR: 1945 AD 9.8 46.45 9.8 46.45