| 1. |
- Ahmed, Moinuddin, et al.
(author)
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Continental-scale temperature variability during the past two millennia
- 2013
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In: Nature Geoscience. - 1752-0894 .- 1752-0908. ; 6:5, s. 339-346
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Journal article (peer-reviewed)abstract
- Past global climate changes had strong regional expression. To elucidate their spatio-temporal pattern, we reconstructed past temperatures for seven continental-scale regions during the past one to two millennia. The most coherent feature in nearly all of the regional temperature reconstructions is a long-term cooling trend, which ended late in the nineteenth century. At multi-decadal to centennial scales, temperature variability shows distinctly different regional patterns, with more similarity within each hemisphere than between them. There were no globally synchronous multi-decadal warm or cold intervals that define a worldwide Medieval Warm Period or Little Ice Age, but all reconstructions show generally cold conditions between ad 1580 and 1880, punctuated in some regions by warm decades during the eighteenth century. The transition to these colder conditions occurred earlier in the Arctic, Europe and Asia than in North America or the Southern Hemisphere regions. Recent warming reversed the long-term cooling; during the period ad 1971–2000, the area-weighted average reconstructed temperature was higher than any other time in nearly 1,400 years.
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| 2. |
- Büntgen, Ulf, et al.
(author)
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Cooling and societal change during the Late Antique Little Ice Age from 536 to around 660 AD
- 2016
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In: Nature Geoscience. - 1752-0894 .- 1752-0908. ; 9:3, s. 231-236
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Journal article (peer-reviewed)abstract
- Climatic changes during the first half of the Common Era have been suggested to play a role in societal reorganizations in Europe and Asia. In particular, the sixth century coincides with rising and falling civilizations, pandemics, human migration and political turmoil. Our understanding of the magnitude and spatial extent as well as the possible causes and concurrences of climate change during this period is, however, still limited. Here we use tree-ring chronologies from the Russian Altai and European Alps to reconstruct summer temperatures over the past two millennia. We find an unprecedented, long-lasting and spatially synchronized cooling following a cluster of large volcanic eruptions in 536, 540 and 547 AD, which was probably sustained by ocean and sea-ice feedbacks, as well as a solar minimum. We thus identify the interval from 536 to about 660 AD as the Late Antique Little Ice Age. Spanning most of the Northern Hemisphere, we suggest that this cold phase be considered as an additional environmental factor contributing to the establishment of the Justinian plague, transformation of the eastern Roman Empire and collapse of the Sasanian Empire, movements out of the Asian steppe and Arabian Peninsula, spread of Slavic-speaking peoples and political upheavals in China.
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| 3. |
- Büntgen, Ulf, et al.
(author)
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Recent European drought extremes beyond Common Era background variability
- 2021
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In: Nature Geoscience. - : Springer Science and Business Media LLC. - 1752-0894 .- 1752-0908. ; 14:4, s. 190-196
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Journal article (peer-reviewed)abstract
- Europe's recent summer droughts have had devastating ecological and economic consequences, but the severity and cause of these extremes remain unclear. Here we present 27,080 annually resolved and absolutely dated measurements of tree-ring stable carbon and oxygen (delta C-13 and delta O-18) isotopes from 21 living and 126 relict oaks (Quercus spp.) used to reconstruct central European summer hydroclimate from 75 bce to 2018 ce. We find that the combined inverse delta C-13 and delta O-18 values correlate with the June-August Palmer Drought Severity Index from 1901-2018 at 0.73 (P < 0.001). Pluvials around 200, 720 and 1100 ce, and droughts around 40, 590, 950 and 1510 ce and in the twenty-first century, are superimposed on a multi-millennial drying trend. Our reconstruction demonstrates that the sequence of recent European summer droughts since 2015 ce is unprecedented in the past 2,110 years. This hydroclimatic anomaly is probably caused by anthropogenic warming and associated changes in the position of the summer jet stream. European summer droughts in recent years are anomalously severe compared with those of the previous 2,000 years, according to a synthesis of annually resolved tree-ring carbon and oxygen isotope records.
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| 4. |
- Büntgen, Ulf, et al.
(author)
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Reply to 'Limited Late Antique cooling'
- 2017
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In: Nature Geoscience. - : Springer Science and Business Media LLC. - 1752-0894 .- 1752-0908. ; 10:4, s. 243-243
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Journal article (other academic/artistic)
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