Reconstructing 800 years of summer temperatures in Scotland from tree rings

• Published in: Climate Dynamics
• Main Authors: Rydval, Miloš, Loader, Neil J., Gunnarson, Björn E., Druckenbrod, Daniel L., Linderholm, Hans W., Moreton, Steven G., Wood, Cheryl Victoria, Wilson, Rob
• Other Authors: NERC, University of St Andrews. Earth and Environmental Sciences, University of St Andrews. Scottish Oceans Institute, University of St Andrews. St Andrews Sustainability Institute
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2017
• Subjects: Temperature reconstruction; Subfossil; Tree-ring; Scots pine; Scotland; GE Environmental Sciences; QH301 Biology; NDAS; GE; QH301; North Atlantic; North Atlantic oscillation
• Online Access: http://hdl.handle.net/10023/10093; https://doi.org/10.1007/s00382-016-3478-8

We thank The Carnegie Trust for the Universities of Scotland for providing funding for Miloš Rydval’s PhD. The Scottish pine network expansion has been an ongoing task since 2007 and funding must be acknowledged to the following projects: EU project ‘Millennium’ (017008-2), Leverhulme Trust project ‘RELiC: Reconstructing 8000 years of Environmental and Landscape change in the Cairngorms (F/00 268/BG)’ and the NERC project ‘SCOT2K: Reconstructing 2000 years of Scottish climate from tree rings (NE/K003097/1)’. This study presents a summer temperature reconstruction using Scots pine tree-ring chronologies for Scotland allowing the placement of current regional temperature changes in a longer-term context. ‘Living-tree’ chronologies were extended using ’subfossil’ samples extracted from nearshore lake sediments resulting in a composite chronology > 800 years in length. The North Cairngorms (NCAIRN) reconstruction was developed from a set of composite blue intensity high-pass and ring-width low-pass chronologies with a range of detrending and disturbance correction procedures. Calibration against July-August mean temperature explains 56.4% of the instrumental data variance over 1866-2009 and is well verified. Spatial correlations reveal strong coherence with temperatures over the British Isles, parts of western Europe, southern Scandinavia and northern parts of the Iberian Peninsula. NCAIRN suggests that the recent summer-time warming in Scotland is likely not unique when compared to multi-decadal warm periods observed in the 1300s, 1500s, and 1730s, although trends before the mid-16th century should be interpreted with some caution due to greater uncertainty. Prominent cold periods were identified from the 16th century until the early 1800s – agreeing with the so-called Little Ice Age observed in other tree-ring reconstructions from Europe - with the 1690s identified as the coldest decade in the record. The reconstruction shows a significant cooling response one year following volcanic eruptions although this result is sensitive to the datasets used to identify such events. In fact, the extreme cold (and warm) years observed in NCAIRN appear more related to internal forcing of the summer North Atlantic Oscillation. Publisher PDF Peer reviewed