Final Report Summary - EU-ISOTREC (Climatic and environmental changes in the Eurasian Subarctic inferred from tree-ring and stable isotope chronologies for the past and recent periods)
(1) We developed a description of climatic and environmental changes in the eastern Taimyr (72 °N, 102 °E) using tree-ring width and stable isotope (d13C, d18O) data based on statistical verification of the relationships to climatic parameters (temperature and precipitation).
To answer the question 'Has the recent warming no analogues in the Siberian north?' we analysed larch tree samples (Larix gmelinii Rupr.) from the permafrost zone in Taymir using tree-ring and stable isotope analyses for the Climatic Optimum Period (COP) 4111 - 3806 BC and Medieval Warm Period (MWP) 917 - 1150 AD, in comparison to the recent period (RP) 1791 - 2008 AD (Sidorova et al. 2013).
We compared our new tree-ring and stable isotope data sets with earlier published July temperature and precipitation reconstructions inferred from pollen data of the Lama Lake, Taimyr Peninsula (Andreev et al. 2000), d18O ice core data from Akademii Nauk ice cap on Severnaya Zemlya (SZ) (Opel et al. 2013) and d18O ice core data from Greenland (GISP2) (Meese et al. 1994), as well as tree-ring width and stable carbon and oxygen isotope data from north-eastern Yakutia (Sidorova et al. 2008). We found that the COP in Taymir was warmer and drier compared to the MWP but rather similar to the RP. Our results indicate that the MWP in Taymir started earlier and was wetter than in Yakutia. Reconstructions of July precipitation obtained from pollen data of the Lama Lake, oxygen isotope data from SZ and our carbon isotopes in tree cellulose agree well and indicate wetter climate conditions during the MWP. Consistent large-scale patterns were reflected in significant links between oxygen isotope data in tree cellulose from Taymir and Yakuti, and oxygen isotope data from SZ and GISP2 during the MWP and the RP.
Finally, we showed that the recent warming is not unprecedented in the Siberian north. Similar climate conditions were recorded by tree-rings, stable isotopes, pollen, and ice core data 6 000 years ago (Sidorova et al. 2013).
(2) A spatial description of climatic changes along high-latitude north-eastern Yakutia (70 °N, 148 °E), eastern Taimyr (72 °N, 102 °E), Central Siberia, Tura (64 °N, 100 °E), Laanila, Finland (65 °N, 25 °E) and high-altitude Siberian Altai (49 °N, 86 °E), the Alps, Loetschental (46 °N, 8 °E), and Mor, Pakistan (33 °N, 73 °E) is presented based on d13C, d18O of larch cellulose chronologies for the period 1900 - 2006. The climatological analysis revealed that d13C and d18O of cellulose chronologies show significant relationships with July temperature and precipitation, which are not observed in tree ring parameters for all studied sites. An increasing trend for d13C and decreasing d18O values of cellulose chronologies were found for high-altitude regions, while the trends were opposite for high-latitude regions. The correlation analysis between d13C in cellulose chronologies and grid July temperature are well represented for all regions. The highest correlations were found for Yakutia, Finland, Loetschental, and Pakistan. For high-latitude sites the distribution represented from east to west and for high-altitude sites from north to south. The spatial distribution of correlation coefficients between d18O in cellulose and July precipitation showed negative relationships for all regions while no significant relationships with tree-ring width chronologies were found. The highest correlations were found for high-altitude sites and weaker for high-latitude sites. This is explained by mixture of temperature and precipitation signals captured by trees growing on the permafrost.
The carbon isotope chronologies from these sites represent the response of larch trees to a slow development of water shortage and carbon dioxide (CO2) effect, while, opposite to the high-latitude sites increasing trends for Altai, Pakistan and Loetschental were found. d18O in tree cellulose for the high-latitude sites: Yakutia, Taymir show increasing trends. For high-altitude sites Altai, Pakistan, Loetschental opposite decreasing trends were found. Declining oxygen trends could be explained by increasing relative humidity or precipitation (Sidorova et al. 2013 to be submitted GCB).
(3) Moreover, we focused our studies on the Siberian transect from north-eastern part of Siberia (Yakutia, Sakha Republic - Yakutia) to southern part (Khakasia). The effect of increasing atmospheric CO2 concentration is clearly visible in the changes of the intrinsic water use efficiency (WUEi) since the last hundred years. Starting in 1900 a steady increase WUEi can be observed with progressing time. Data show a clear transect from North to South with increasing values. Although WUEi in Khakasia, the most southern site, was already highest of all five sites at the beginning of the 20th century, and still increased until the beginning of the 21st century, its rate of change was rather low within the last 104 years. The most dramatic change in WUEi is found at Enisseysk (ENI), the next southernmost site. In Tura and Taimyr WUEi still increases but the curves tend towards a saturation, with a rate of change tending towards zero. Yakutia with the lowest WUEi values steadily increases, which is somewhat surprising as this is the most northern site, with the harshest environmental growth conditions characterised by a strong increase of atmospheric CO2, which clearly has physiological implications.
(4) Recently published, improved chronologies for volcanic sulfate in Greenland and Antarctic ice permit a comparison with the growth responses of absolutely dated tree rings at three locations in Siberia for a putative cluster of three climatically effective volcanic eruptions centered on AD 536. Tree-ring width, cell-wall thickness, cellulose d13C and d18O were measured on multiple samples of larch wood from two sites close to the northern limit of tree growth on the Taimyr Peninsula and in north-eastern Yakutia, and at a high-elevation, more southern, location in the Altai Mts. The AD 536 event was associated with different, but marked changes in tree-ring parameters at the high-latitude sites compared with the high elevation site. The volcanic events ending in AD 532 and AD 541 were associated with their own distinctive tree-ring responses across the three sites and multiple variables. The combination of improved chronologies for the climatically effective volcanic eruptions of this part of the 6th century AD, and an array of sites with different climates and multiple tree-ring variables permits a richer description of tree responses to this cluster of events (Sidorova et al. 2013 PLOS one, submitted).
(5) To simulate d13C data and compare results with measured d13C data (Sidorova et al. 2008) we used the ORCHIDEE model (Lafont et al. 2012), which was used to simulate ecosystem energy, water, and carbon fluxes at half-hourly to decadal time scales, the eco-physiological model (EPM) developed by Hemming et al. (2001) and the land surface processes (LPX) and exchanges model by Spahni et al. (2012). The mechanistic Roden-Lin-Ehleringer model (Roden et al. 2000) was used to quantify both the physical and biochemical fractionation events associated with hydrogen and oxygen isotope ratios in tree-ring cellulose.
Simulation results (Sidorova et al. in preparation, GRL) were compared with measured data (Sidorova et al. 2008, 2013). We found a good correspondence in the long-term trends between modelled and measured data. Predictions of carbon isotope ratios from models were consistent with measured data. The Roden-Lin-Ehleringer oxygen model allowed to predict humidity and source water enrichment as well as oxygen isotope effects associated with leaf water enrichment.
(6) Results of this project give new interesting insights on the problem of global warming in the north. In the context of past climatic changes, recent warming is not extraordinary in the Siberian north and has analogues in the past (Sidorova et al. 2013). However, during the last decades trees from Siberian north started to respond to developing of water shortage (Sidorova et al. 2009, 2011). If the warming trend will continuously increase, as it was during the recent decades, we could expect that trees would be exposed to severe drought stress; the number of fire events will increase as well as insect attacks. Our improved knowledge from this project gives us the tools to develop the right directions and strategies for the Russian forest management, which undoubtedly will impact the socio-economic environment.
References:
Andreev AA, Siegert C, Klimanov VA, et al. (2002) Late Pleistocene and Holocene vegetation and climate on the Taymirmyr lowland, northern Siberia. Quaternary research, 1, V. 57. p. 138-150
Hemming D, Fritts H, Leavitt SW, Wright W, Long A, Shashkin A (2001) Modeling tree-ring ?13 C. Dendrochronologia 19(1):23-38
Lafont, S., Zhao, Y., Calvet, J.-C. Peylin, P., Ciais, P., Maignan, F. and Weiss, M.: 2012, 'Modelling LAI, surface water and carbon fluxes at high-resolution over France: comparison of ISBA-A-gs and ORCHIDEE', Geophysical Research Biogeosciences 9, 439-456.
Meese DA, Alley RB, Gow AJ (1994) The accumulation record from the GISP2 core as an indicator of climate change throughout the Holocene, Science, 266: 1680-1682
Opel T, Fritzsche D, Meyer H, (2013) Eurasian Arctic climate over the past millennium as recorded in the Akademii Nauk ice core (Severnaya Zemlya). Climate of the Past Discussions 9, 2401-2413.
Roden JS, Lin G, Ehleringer JR (2000) A mechanistic model for interpretation of hydrogen and oxygen isotope ratios in treering cellulose. Geochimica et Cosmochimica Acta 64, 21-35. doi: 10.1016/S0016-7037(99)00195-7
Sidorova OV, Saurer M, Andreev A, Fritzsche D, Opel T, Naurzbaev M, Siegwolf R (2013) Is the 20th century warming unprecedented in the Siberian north? Quaternary Science Review, V.73 p. 93-102
Sidorova OV, Siegwolf R, Myglan VS, Bryukhanova MV, Kirdyanov AV, Treydte K, Kress A, Saurer M. Recent and past climatic changes in the high-latitude and high-altitude regions inferred from tree-rings and stable isotopes. Global Change Biology
Sidorova OV, Siegwolf R, Saurer M, Shashkin AV, Knorre AA, Prokushkin AS, Vaganov EA, Kirdyanov AA (2009) Do centennial tree-ring and stable isotope trends of Larix gmelinii (Rupr.) Rupr. indicate increasing water shortage in the Siberian north? Oecologia, 10.1007/s00442-009-1411-0 p. 1432-1939
Sidorova OV, Siegwolf RTW, Saurer MM, Naurzbaev MM, Shashkin AV, Vaganov EA (2011) Spatial patterns of climatic changes in the Eurasian north reflected in Siberian larch tree-ring parameters and stable isotopes. Global Change Biology, 10.1111/j.1365-2486.2009.02008.x 16, p. 1003-1018
Sidorova OV, Siegwolf RTW, Saurer MM, Naurzbaev MM, Vaganov EA (2008) Isotopic composition (d13C, d18O) in Siberian tree-ring chronology. J. Geophys. Res. Biogeoscinces, 113,G02019,doi:10.1029/2007JG000473
Spahni R, Joos F, Stocker BD, Steinacher M, Yu ZC (2012) Transient simulations of the carbon and nitrogen dynamics in northern peatlands: from the Last Glacial Maximum to the 21st century. Climate Past Discussion 8: 56335685
To answer the question 'Has the recent warming no analogues in the Siberian north?' we analysed larch tree samples (Larix gmelinii Rupr.) from the permafrost zone in Taymir using tree-ring and stable isotope analyses for the Climatic Optimum Period (COP) 4111 - 3806 BC and Medieval Warm Period (MWP) 917 - 1150 AD, in comparison to the recent period (RP) 1791 - 2008 AD (Sidorova et al. 2013).
We compared our new tree-ring and stable isotope data sets with earlier published July temperature and precipitation reconstructions inferred from pollen data of the Lama Lake, Taimyr Peninsula (Andreev et al. 2000), d18O ice core data from Akademii Nauk ice cap on Severnaya Zemlya (SZ) (Opel et al. 2013) and d18O ice core data from Greenland (GISP2) (Meese et al. 1994), as well as tree-ring width and stable carbon and oxygen isotope data from north-eastern Yakutia (Sidorova et al. 2008). We found that the COP in Taymir was warmer and drier compared to the MWP but rather similar to the RP. Our results indicate that the MWP in Taymir started earlier and was wetter than in Yakutia. Reconstructions of July precipitation obtained from pollen data of the Lama Lake, oxygen isotope data from SZ and our carbon isotopes in tree cellulose agree well and indicate wetter climate conditions during the MWP. Consistent large-scale patterns were reflected in significant links between oxygen isotope data in tree cellulose from Taymir and Yakuti, and oxygen isotope data from SZ and GISP2 during the MWP and the RP.
Finally, we showed that the recent warming is not unprecedented in the Siberian north. Similar climate conditions were recorded by tree-rings, stable isotopes, pollen, and ice core data 6 000 years ago (Sidorova et al. 2013).
(2) A spatial description of climatic changes along high-latitude north-eastern Yakutia (70 °N, 148 °E), eastern Taimyr (72 °N, 102 °E), Central Siberia, Tura (64 °N, 100 °E), Laanila, Finland (65 °N, 25 °E) and high-altitude Siberian Altai (49 °N, 86 °E), the Alps, Loetschental (46 °N, 8 °E), and Mor, Pakistan (33 °N, 73 °E) is presented based on d13C, d18O of larch cellulose chronologies for the period 1900 - 2006. The climatological analysis revealed that d13C and d18O of cellulose chronologies show significant relationships with July temperature and precipitation, which are not observed in tree ring parameters for all studied sites. An increasing trend for d13C and decreasing d18O values of cellulose chronologies were found for high-altitude regions, while the trends were opposite for high-latitude regions. The correlation analysis between d13C in cellulose chronologies and grid July temperature are well represented for all regions. The highest correlations were found for Yakutia, Finland, Loetschental, and Pakistan. For high-latitude sites the distribution represented from east to west and for high-altitude sites from north to south. The spatial distribution of correlation coefficients between d18O in cellulose and July precipitation showed negative relationships for all regions while no significant relationships with tree-ring width chronologies were found. The highest correlations were found for high-altitude sites and weaker for high-latitude sites. This is explained by mixture of temperature and precipitation signals captured by trees growing on the permafrost.
The carbon isotope chronologies from these sites represent the response of larch trees to a slow development of water shortage and carbon dioxide (CO2) effect, while, opposite to the high-latitude sites increasing trends for Altai, Pakistan and Loetschental were found. d18O in tree cellulose for the high-latitude sites: Yakutia, Taymir show increasing trends. For high-altitude sites Altai, Pakistan, Loetschental opposite decreasing trends were found. Declining oxygen trends could be explained by increasing relative humidity or precipitation (Sidorova et al. 2013 to be submitted GCB).
(3) Moreover, we focused our studies on the Siberian transect from north-eastern part of Siberia (Yakutia, Sakha Republic - Yakutia) to southern part (Khakasia). The effect of increasing atmospheric CO2 concentration is clearly visible in the changes of the intrinsic water use efficiency (WUEi) since the last hundred years. Starting in 1900 a steady increase WUEi can be observed with progressing time. Data show a clear transect from North to South with increasing values. Although WUEi in Khakasia, the most southern site, was already highest of all five sites at the beginning of the 20th century, and still increased until the beginning of the 21st century, its rate of change was rather low within the last 104 years. The most dramatic change in WUEi is found at Enisseysk (ENI), the next southernmost site. In Tura and Taimyr WUEi still increases but the curves tend towards a saturation, with a rate of change tending towards zero. Yakutia with the lowest WUEi values steadily increases, which is somewhat surprising as this is the most northern site, with the harshest environmental growth conditions characterised by a strong increase of atmospheric CO2, which clearly has physiological implications.
(4) Recently published, improved chronologies for volcanic sulfate in Greenland and Antarctic ice permit a comparison with the growth responses of absolutely dated tree rings at three locations in Siberia for a putative cluster of three climatically effective volcanic eruptions centered on AD 536. Tree-ring width, cell-wall thickness, cellulose d13C and d18O were measured on multiple samples of larch wood from two sites close to the northern limit of tree growth on the Taimyr Peninsula and in north-eastern Yakutia, and at a high-elevation, more southern, location in the Altai Mts. The AD 536 event was associated with different, but marked changes in tree-ring parameters at the high-latitude sites compared with the high elevation site. The volcanic events ending in AD 532 and AD 541 were associated with their own distinctive tree-ring responses across the three sites and multiple variables. The combination of improved chronologies for the climatically effective volcanic eruptions of this part of the 6th century AD, and an array of sites with different climates and multiple tree-ring variables permits a richer description of tree responses to this cluster of events (Sidorova et al. 2013 PLOS one, submitted).
(5) To simulate d13C data and compare results with measured d13C data (Sidorova et al. 2008) we used the ORCHIDEE model (Lafont et al. 2012), which was used to simulate ecosystem energy, water, and carbon fluxes at half-hourly to decadal time scales, the eco-physiological model (EPM) developed by Hemming et al. (2001) and the land surface processes (LPX) and exchanges model by Spahni et al. (2012). The mechanistic Roden-Lin-Ehleringer model (Roden et al. 2000) was used to quantify both the physical and biochemical fractionation events associated with hydrogen and oxygen isotope ratios in tree-ring cellulose.
Simulation results (Sidorova et al. in preparation, GRL) were compared with measured data (Sidorova et al. 2008, 2013). We found a good correspondence in the long-term trends between modelled and measured data. Predictions of carbon isotope ratios from models were consistent with measured data. The Roden-Lin-Ehleringer oxygen model allowed to predict humidity and source water enrichment as well as oxygen isotope effects associated with leaf water enrichment.
(6) Results of this project give new interesting insights on the problem of global warming in the north. In the context of past climatic changes, recent warming is not extraordinary in the Siberian north and has analogues in the past (Sidorova et al. 2013). However, during the last decades trees from Siberian north started to respond to developing of water shortage (Sidorova et al. 2009, 2011). If the warming trend will continuously increase, as it was during the recent decades, we could expect that trees would be exposed to severe drought stress; the number of fire events will increase as well as insect attacks. Our improved knowledge from this project gives us the tools to develop the right directions and strategies for the Russian forest management, which undoubtedly will impact the socio-economic environment.
References:
Andreev AA, Siegert C, Klimanov VA, et al. (2002) Late Pleistocene and Holocene vegetation and climate on the Taymirmyr lowland, northern Siberia. Quaternary research, 1, V. 57. p. 138-150
Hemming D, Fritts H, Leavitt SW, Wright W, Long A, Shashkin A (2001) Modeling tree-ring ?13 C. Dendrochronologia 19(1):23-38
Lafont, S., Zhao, Y., Calvet, J.-C. Peylin, P., Ciais, P., Maignan, F. and Weiss, M.: 2012, 'Modelling LAI, surface water and carbon fluxes at high-resolution over France: comparison of ISBA-A-gs and ORCHIDEE', Geophysical Research Biogeosciences 9, 439-456.
Meese DA, Alley RB, Gow AJ (1994) The accumulation record from the GISP2 core as an indicator of climate change throughout the Holocene, Science, 266: 1680-1682
Opel T, Fritzsche D, Meyer H, (2013) Eurasian Arctic climate over the past millennium as recorded in the Akademii Nauk ice core (Severnaya Zemlya). Climate of the Past Discussions 9, 2401-2413.
Roden JS, Lin G, Ehleringer JR (2000) A mechanistic model for interpretation of hydrogen and oxygen isotope ratios in treering cellulose. Geochimica et Cosmochimica Acta 64, 21-35. doi: 10.1016/S0016-7037(99)00195-7
Sidorova OV, Saurer M, Andreev A, Fritzsche D, Opel T, Naurzbaev M, Siegwolf R (2013) Is the 20th century warming unprecedented in the Siberian north? Quaternary Science Review, V.73 p. 93-102
Sidorova OV, Siegwolf R, Myglan VS, Bryukhanova MV, Kirdyanov AV, Treydte K, Kress A, Saurer M. Recent and past climatic changes in the high-latitude and high-altitude regions inferred from tree-rings and stable isotopes. Global Change Biology
Sidorova OV, Siegwolf R, Saurer M, Shashkin AV, Knorre AA, Prokushkin AS, Vaganov EA, Kirdyanov AA (2009) Do centennial tree-ring and stable isotope trends of Larix gmelinii (Rupr.) Rupr. indicate increasing water shortage in the Siberian north? Oecologia, 10.1007/s00442-009-1411-0 p. 1432-1939
Sidorova OV, Siegwolf RTW, Saurer MM, Naurzbaev MM, Shashkin AV, Vaganov EA (2011) Spatial patterns of climatic changes in the Eurasian north reflected in Siberian larch tree-ring parameters and stable isotopes. Global Change Biology, 10.1111/j.1365-2486.2009.02008.x 16, p. 1003-1018
Sidorova OV, Siegwolf RTW, Saurer MM, Naurzbaev MM, Vaganov EA (2008) Isotopic composition (d13C, d18O) in Siberian tree-ring chronology. J. Geophys. Res. Biogeoscinces, 113,G02019,doi:10.1029/2007JG000473
Spahni R, Joos F, Stocker BD, Steinacher M, Yu ZC (2012) Transient simulations of the carbon and nitrogen dynamics in northern peatlands: from the Last Glacial Maximum to the 21st century. Climate Past Discussion 8: 56335685