Stable carbon isotopes from Torneträsk, northern Sweden provide a millennial length reconstruction of summer sunshine and its relationship to Arctic circulation

Loader, Neil J.; Young, Giles H.F.; Grudd, Håkan; McCarroll, Danny

doi:10.1016/j.quascirev.2012.11.014

Cited by 120 publications

(120 citation statements)

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“…In both steps (3) and (4), atmospheric CO 2 is prescribed following Law Dome data (Etheridge et al, 1996;MacFarling Meure et al, 2006) and atmospheric samples; prescribed atmospheric δ 13 C is a combination of data from Rubino et al (2013) and, from 1993 on, White et al (2015) ( Fig. 1).…”

Section: Spin-up and Transient Simulations And Model Forcingsmentioning

confidence: 99%

20th century changes in carbon isotopes and water-use efficiency: tree-ring-based evaluation of the CLM4.5 and LPX-Bern models

et al. 2017

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Abstract. Measurements of the stable carbon isotope ratio (δ 13 C) on annual tree rings offer new opportunities to evaluate mechanisms of variations in photosynthesis and stomatal conductance under changing CO 2 and climate conditions, especially in conjunction with process-based biogeochemical model simulations. The isotopic discrimination is indicative of the ratio between the CO 2 partial pressure in the intercellular cavities and the atmosphere (c i /c a ) and of the ratio of assimilation to stomatal conductance, termed intrinsic wateruse efficiency (iWUE). We performed isotope-enabled simulations over the industrial period with the land biosphere module (CLM4.5) of the Community Earth System Model and the Land Surface Processes and Exchanges (LPX-Bern) dynamic global vegetation model. Results for C3 tree species show good agreement with a global compilation of δ 13 C measurements on leaves, though modeled 13 C discrimination by C3 trees is smaller in arid regions than measured. A compilation of 76 tree-ring records, mainly from Europe, boreal Asia, and western North America, suggests on average small 20th century changes in isotopic discrimination and in c i /c a and an increase in iWUE of about 27 % since 1900. LPXBern results match these century-scale reconstructions, supporting the idea that the physiology of stomata has evolved to optimize trade-offs between carbon gain by assimilation and water loss by transpiration. In contrast, CLM4.5 simulates an increase in discrimination and in turn a change in iWUE that is almost twice as large as that revealed by the tree-ring data. Factorial simulations show that these changes are mainly in response to rising atmospheric CO 2 . The results suggest that the downregulation of c i /c a and of photosynthesis by nitrogen limitation is possibly too strong in the standard setup of CLM4.5 or that there may be problems associated with the implementation of conductance, assimilation, and related adjustment processes on long-term environmental changes.

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Section: Spin-up and Transient Simulations And Model Forcingsmentioning

confidence: 99%

20th century changes in carbon isotopes and water-use efficiency: tree-ring-based evaluation of the CLM4.5 and LPX-Bern models

et al. 2017

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“…In addition to providing reconstructions of local warm-season temperature variability (Grudd 2008;Gunnarson et al 2011;Melvin et al 2013) and past changes in cloud cover and sunshine (Young et al 2012;Loader et al 2013) from single-site data, some of these chronologies have been included in multi-site studies to infer past regional climates (Büntgen et al 2011b;Esper et al 2012;McCarroll et al 2013). Still, looking at the spatial expression of the above mentioned "supra long" chronologies as well as regional reconstructions based on trees from northernmost Sweden, it is evident that they mainly represent their own regions and not the whole of Fennoscandia.…”

Section: Introductionmentioning

confidence: 99%

Fennoscandia revisited: a spatially improved tree-ring reconstruction of summer temperatures for the last 900 years

et al. 2014

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of the forcings of JJA mean temperatures in the region shows an association with sea-surface temperature over the eastern North Atlantic, but also the subpolar and subtropical gyres. Moreover, using Superposed Epoch Analysis, a significant cooling in the year following a volcanic eruption was noted, and for the largest explosive eruptions, the effect could remain for up to 4 years. This new improved reconstruction provides a mean to reinforce our understanding of forcings on summer temperatures in the North European sector.

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“…Waterhouse et al, 2000;Holzkämper et al, 2008;2012;Sidorova et al, 2008;Porter et al, 2009). The combination of long-lived trees, robust dendrochronologies and excellent sample preservation both on land and in lakes have facilitated the development of several multi-centennial to millennial length isotopic records (Boettger et al, 2003;Kremenetski et al, 2004;Sidorova et al, 2008;Young et al, 2010;Gagen et al, 2011;Loader et al, 2013;Porter et al, 2014). However, because moisture is rarely the dominant tree-growth limiting factor across much of the Arctic region, there 10 is a limitation of the hydroclimate information that can be reconstructed using the isotopic approach.…”

Section: Stable Isotopes In Tree Rings 20mentioning

confidence: 99%

“…However, because moisture is rarely the dominant tree-growth limiting factor across much of the Arctic region, there 10 is a limitation of the hydroclimate information that can be reconstructed using the isotopic approach. Using a multiparameter approach several studies (Loader et al, 2013;Young et al, 2010;2012;Gagen et al, 2011) provided sunshine/cloud estimates and were able to demonstrate large-scale shifts in the dominance of Arctic and Maritime air masses over the Northern Fennoscandian region during the Little Ice Age and Mediaeval period. Such multi-parameter studies are potentially very powerful as they help to develop testable hypotheses relating to the future response of the Arctic atmosphere 15 and provide a foundation for developing a circum-polar isotope network to track changes in atmospheric circulation and its relationship to climate throughout the Common Era.…”

Section: Stable Isotopes In Tree Rings 20mentioning

confidence: 99%

Arctic hydroclimate variability during the last 2000 years – current understanding and research challenges

Linderholm¹,

Nicolle²,

Francus³

et al. 2017

Preprint

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Abstract. Along with Arctic amplification, changes in Arctic hydroclimate have become increasingly apparent. Reanalysis data show increasing trends in Arctic temperature and precipitation over the 20 th century, but changes are not homogenous 30 across seasons or space. The observed hydroclimate changes are expected to continue, and possibly accelerate, in the coming century, not only affecting pan-Arctic natural ecosystems and human activities, but also lower latitudes through changes in atmospheric and oceanic circulation. However, a lack of spatiotemporal observational data makes reliable quantification of Arctic hydroclimate change difficult, especially in a long-term context. To understand hydroclimate variability and the mechanisms driving observed changes, beyond the instrumental record, climate proxies are needed. Here we bring together 35 the current understanding of Arctic hydroclimate during the past 2000 years, as inferred from natural archives and proxies and palaeoclimate model simulations. Inadequate proxy data coverage is apparent, with distinct data gaps in most of Eurasia and parts of North America, which makes robust assessments for the whole Arctic currently impossible. Hydroclimate proxies and climate models indicate that the Medieval Climate Anomaly (MCA) was anomalously wet, while conditions Clim. Past Discuss., doi:10.5194/cp-2017Discuss., doi:10.5194/cp- -34, 2017 Manuscript under review for journal Clim. Past Discussion started: 17 March 2017 c Author(s) 2017. CC-BY 3.0 License. 2 were in general drier during the Little Ice Age (LIA), relative to the last 2000 years. However, it is clear that there are large regional differences, which are especially evident during the LIA. Due to the spatiotemporal differences in Arctic hydroclimate, we recommend detailed regional studies, e.g. including field reconstructions, to disentangle spatial patterns and potential forcing factors. At present, it is only possible to carry out regional syntheses for a few areas of the Arctic, e.g. Fennoscandia, Greenland and western North America. To fully assess pan-Arctic hydroclimate variability for the last two 5 millennia additional proxy records are required.

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Stable carbon isotopes from Torneträsk, northern Sweden provide a millennial length reconstruction of summer sunshine and its relationship to Arctic circulation

Cited by 120 publications

References 105 publications

20th century changes in carbon isotopes and water-use efficiency: tree-ring-based evaluation of the CLM4.5 and LPX-Bern models

20th century changes in carbon isotopes and water-use efficiency: tree-ring-based evaluation of the CLM4.5 and LPX-Bern models

Fennoscandia revisited: a spatially improved tree-ring reconstruction of summer temperatures for the last 900 years

Arctic hydroclimate variability during the last 2000 years – current understanding and research challenges

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