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In the paper, potential analysis of various growth parameters of Norway spruceare introduced at the macro and micro levels. Dendroecological measurements give information as to xylem growth ring widths, their density and content of stable isotopes in the xylem growth rings. Needle trace method of the terminal annual shoot allows retrospective view into needle density ofthe terminal annual shoot and consequently reconstruction of the several parameters linked to the needles and air pollution. Using pinning method, it is possible to follow intra-annual dynamics of the radial growth of trees at the cellular level and furthermore investigate the effect of climatic factorson cambial activity. V prispevku so predstavljene možnosti analize različnih rastnih parametrov navadne smreke na makro in mikro nivoju. Dendroekološke meritve nam dajo informacijo o širinah branik, gostotah branik in vsebnosti stabilnih izotopov ogljika v njih na nivoju branike ter jih retrospektivno povezati z različnimi okoljskimi informacijami. Metoda preučevanja sledi iglic terminalnega poganjkanam omogoča rekonstrukcijo gostote iglic terminalnega poganjka in posledično analizo številnih parametrov, vezanih na iglice in zračno polucijo.Z metodo pinning je mogoče slediti intraanualno dinamiko debelinske rasti drevesa na celičnem nivoju in nadalje raziskati vpliv klimatskih dejavnikov na kambijevo aktivnost.

The spatial context is critical when assessing present-day climate anomalies, attributing them to potential forcings and making statements regarding their frequency and severity in a long-term perspective. Recent international initiatives have expanded the number of high-quality proxy-records and developed new statistical reconstruction methods. These advances allow more rigorous regional past temperature reconstructions and, in turn, the possibility of evaluating climate models on policy-relevant, spatio-temporal scales. Here we provide a new proxy-based, annually-resolved, spatial reconstruction of the European summer (June–August) temperature fields back to 755 CE based on Bayesian hierarchical modelling (BHM), together with estimates of the European mean temperature variation since 138 BCE based on BHM and composite-plus-scaling (CPS). Our reconstructions compare well with independent instrumental and proxy-based temperature estimates, but suggest a larger amplitude in summer temperature variability than previously reported. Both CPS and BHM reconstructions indicate that the mean 20th century European summer temperature was not significantly different from some earlier centuries, including the 1st, 2nd, 8th and 10th centuries CE. The 1st century (in BHM also the 10th century) may even have been slightly warmer than the 20th century, but the difference is not statistically significant. Comparing each 50 yr period with the 1951–2000 period reveals a similar pattern. Recent summers, however, have been unusually warm in the context of the last two millennia and there are no 30 yr periods in either reconstruction that exceed the mean average European summer temperature of the last 3 decades (1986–2015 CE). A comparison with an ensemble of climate model simulations suggests that the reconstructed European summer temperature variability over the period 850–2000 CE reflects changes in both internal variability and external forcing on multi-decadal time-scales. For pan-European temperatures we find slightly better agreement between the reconstruction and the model simulations with high-end estimates for total solar irradiance. Temperature differences between the medieval period, the recent period and the Little Ice Age are larger in the reconstructions than the simulations. This may indicate inflated variability of the reconstructions, a lack of sensitivity and processes to changes in external forcing on the simulated European climate and/or an underestimation of internal variability on centennial and longer time scales., Support for PAGES 2k activities is provided by the US and Swiss National Science Foundations, US National Oceanographic and Atmospheric Administration and by the International Geosphere-Biosphere Programme. JPWacknowledges support from the Centre of Climate Dynamics (SKD), Bergen. The work of OB, SW and EZ is part of CLISAP. JL, SW, EZ, JPW, JGN, OB also acknowledge support by the German Science Foundation Project ‘Precipitation in the past millennia in Europe–Extensionback toRoman times’.MBacknowledges the Catalan Meteorological Survey (SMC), National Programme I+D, Project CGL2011-28255. PD and RB acknowledge support from the Czech Science Foundation project no. GA13-04291S. VK was supported by Russian Science Foundation (grant 14- 19-00765) and the Russian Foundation for Humanities (grants 15-07-00012, 15-37-11129). GH and AS are supported by the ERC funded project TITAN (EC- 320691). GH was further funded by the Wolfson Foundation and the Royal Society as a Royal Society Wolfson Research Merit Award (WM130060) holder. NY is funded by the LOEWEexcellence cluster FACE2- FACE of the Hessen State Ministry of Higher Education, Research and the Arts; HZ acknowledge support from the DFG project AFICHE. Lamont contribution #7961. The reconstructions can be downloaded from the NOAA paleoclimate homepage: www.ncdc.noaa. gov/paleo/study/19600. LFD, EGB and JFGR were supported by grants CGL2011-29677-c02-02 and CGL2014-599644-R. All authors are part of the Euro- Med 2kConsortium.

Cloud cover is one of the most important factors controlling the radiation balance of the Earth. The response of cloud cover to increasing global temperatures represents the largest uncertainty in model estimates of future climate because the cloud response to temperature is not well-constrained. Here we present the first regional reconstruction of summer sunshine over the past millennium, based on the stable carbon isotope ratios of pine treerings from Fennoscandia. Comparison with the regional temperature evolution reveals the Little Ice Age (LIA) to have been sunny, with cloudy conditions in the warmest periods of the Medieval at this site. A negative shortwave cloud feedback is indicated at high latitude. A millennial climate simulation suggests that regionally low temperatures during the LIA were mostly maintained by a weaker greenhouse effect due to lower humidity. Simulations of future climate that display a negative shortwave cloud feedback for high-latitudes are consistent with our proxy interpretation.

In the paper, potential analysis of various growth parameters of Norway spruceare introduced at the macro and micro levels. Dendroecological measurements give information as to xylem growth ring widths, their density and content of stable isotopes in the xylem growth rings. Needle trace method of the terminal annual shoot allows retrospective view into needle density ofthe terminal annual shoot and consequently reconstruction of the several parameters linked to the needles and air pollution. Using pinning method, it is possible to follow intra-annual dynamics of the radial growth of trees at the cellular level and furthermore investigate the effect of climatic factorson cambial activity. V prispevku so predstavljene možnosti analize različnih rastnih parametrov navadne smreke na makro in mikro nivoju. Dendroekološke meritve nam dajo informacijo o širinah branik, gostotah branik in vsebnosti stabilnih izotopov ogljika v njih na nivoju branike ter jih retrospektivno povezati z različnimi okoljskimi informacijami. Metoda preučevanja sledi iglic terminalnega poganjkanam omogoča rekonstrukcijo gostote iglic terminalnega poganjka in posledično analizo številnih parametrov, vezanih na iglice in zračno polucijo.Z metodo pinning je mogoče slediti intraanualno dinamiko debelinske rasti drevesa na celičnem nivoju in nadalje raziskati vpliv klimatskih dejavnikov na kambijevo aktivnost.

In southern Africa long-term regional rainfall data sets are very limited such that the variability of rainfall across the region is poorly understood. With available climate records so limited the development of strong proxy records are vital to develop drought management plans. In our continuing efforts to develop such proxy records we present the results of an investigation into the dendrochronological potential of Widdringtonia nodiflora and Widdringtonia schwarzii. We sampled W. schwarzii, from the area it is endemic to, the Baviaanskloof wilderness area, in the Langkloof region of the Eastern Cape Province. Widdringtonia nodiflora samples were collected from the Grootvadersbosch Nature Reserve near Heidelberg in the Western Cape Province. The results indicate that inconsistencies in ring width combined with poorly defined ring boundaries and converging rings make cross-dating between different trees from the same locality an impossible task for both species using manageable sample numbers. Without cross-dating, chronology development is an equally impossible task for both W. nodiflora and W. schwarzii. As with W. cedarbergensis, W. schwarzii may avoid drought stress by accessing deep water. This may explain the many false rings and poorly defined ring boundaries apparent in this species. This study concludes the dendrochronological assessment of all of the Widdringtonia species with only two South African conifers not evaluated (Podocarpus henkelii and P. elongatus). Widdringtonia cedarbergensis is the only South African conifer that has been successfully cross- dated, however, there are no significant correlations between ring width indices and climate variables for this species.

The spatial context is critical when assessing present-day climate anomalies, attributing them to potential forcings and making statements regarding their frequency and severity in a long-term perspective. Recent international initiatives have expanded the number of high-quality proxy-records and developed new statistical reconstruction methods. These advances allow more rigorous regional past temperature reconstructions and, in turn, the possibility of evaluating climate models on policy-relevant, spatio-temporal scales. Here we provide a new proxy-based, annually-resolved, spatial reconstruction of the European summer (June–August) temperature fields back to 755 CE based on Bayesian hierarchical modelling (BHM), together with estimates of the European mean temperature variation since 138 BCE based on BHM and composite-plus-scaling (CPS). Our reconstructions compare well with independent instrumental and proxy-based temperature estimates, but suggest a larger amplitude in summer temperature variability than previously reported. Both CPS and BHM reconstructions indicate that the mean 20th century European summer temperature was not significantly different from some earlier centuries, including the 1st, 2nd, 8th and 10th centuries CE. The 1st century (in BHM also the 10th century) may even have been slightly warmer than the 20th century, but the difference is not statistically significant. Comparing each 50 yr period with the 1951–2000 period reveals a similar pattern. Recent summers, however, have been unusually warm in the context of the last two millennia and there are no 30 yr periods in either reconstruction that exceed the mean average European summer temperature of the last 3 decades (1986–2015 CE). A comparison with an ensemble of climate model simulations suggests that the reconstructed European summer temperature variability over the period 850–2000 CE reflects changes in both internal variability and external forcing on multi-decadal time-scales. For pan-European temperatures we find slightly better agreement between the reconstruction and the model simulations with high-end estimates for total solar irradiance. Temperature differences between the medieval period, the recent period and the Little Ice Age are larger in the reconstructions than the simulations. This may indicate inflated variability of the reconstructions, a lack of sensitivity and processes to changes in external forcing on the simulated European climate and/or an underestimation of internal variability on centennial and longer time scales.

The spatial context is critical when assessing present-day climate anomalies, attributing them to potential forcings and making statements regarding their frequency and severity in a long-term perspective. Recent international initiatives have expanded the number of high-quality proxy-records and developed new statistical reconstruction methods. These advances allow more rigorous regional past temperature reconstructions and, in turn, the possibility of evaluating climate models on policy-relevant, spatio-temporal scales. Here we provide a new proxy-based, annually-resolved, spatial reconstruction of the European summer (June–August) temperature fields back to 755 CE based on Bayesian hierarchical modelling (BHM), together with estimates of the European mean temperature variation since 138 BCE based on BHM and composite-plus-scaling (CPS). Our reconstructions compare well with independent instrumental and proxy-based temperature estimates, but suggest a larger amplitude in summer temperature variability than previously reported. Both CPS and BHM reconstructions indicate that the mean 20th century European summer temperature was not significantly different from some earlier centuries, including the 1st, 2nd, 8th and 10th centuries CE. The 1st century (in BHM also the 10th century) may even have been slightly warmer than the 20th century, but the difference is not statistically significant. Comparing each 50 yr period with the 1951–2000 period reveals a similar pattern. Recent summers, however, have been unusually warm in the context of the last two millennia and there are no 30 yr periods in either reconstruction that exceed the mean average European summer temperature of the last 3 decades (1986–2015 CE). A comparison with an ensemble of climate model simulations suggests that the reconstructed European summer temperature variability over the period 850–2000 CE reflects changes in both internal variability and external forcing on multi-decadal time-scales. For pan-European temperatures we find slightly better agreement between the reconstruction and the model simulations with high-end estimates for total solar irradiance. Temperature differences between the medieval period, the recent period and the Little Ice Age are larger in the reconstructions than the simulations. This may indicate inflated variability of the reconstructions, a lack of sensitivity and processes to changes in external forcing on the simulated European climate and/or an underestimation of internal variability on centennial and longer time scales.