從德國黑森Herbstlabyrinth洞穴的一株石筍以及格陵蘭的冰芯這兩種自然界不同的氣候紀錄得出了時間一致的數據，使研究人員對於歐洲中部的急遽氣候變遷的發生年代有了新的認知。位於現今德國萊茵蘭—普法爾茨州的拉赫湖(Laacher
See)火山曾經發生過劇烈的噴發，而這項分析顯示噴發年代比之前推論的還早，因此不可能引發距今13000年前左右突然開始的低溫時期。由德國海德堡大學與美因茲大學的地球科學家進行的研究證實了這項發現。除了對拉赫湖火山噴發進行精確的定年之外，研究團隊也估計了它對氣候造成的衝擊。
德國黑森Breitscheid的Herbstlabyrinth洞穴裡的一株石筍使研究人員精準定出拉赫湖火山噴發的時間。圖片來源：Ingo Dorsten, Speleological Working Group Hessen e.V. (SAH)
拉赫湖火山最近一次的噴發被認為是過去兩百萬年來最嚴重的噴發事件之一，其影響遠至義大利北部、斯堪地那維亞、俄羅斯……等地。不過這場噴發的確切發生時間，以及它是否直接促成了稱為「新仙女木期」的驟冷時期，一直以來都是個討論熱烈的科學議題。2021年一篇研究透過樹幹的放射性碳同位素定年結果來進行全新的時序分類，結果認為拉赫湖火山噴發的年代勢必比之前的推論還早了130年。而海德堡大學與美因茲大學的研究團隊運用德國布賴特沙伊德的Herbstlabyrinth洞內的一株石筍，佐證了這個新提出的年代。
由於火山噴發會釋放大量的硫，因而成為一種火山訊號呈現在石筍當中。Axel
Schmitt博士是澳洲伯斯科廷大學的研究人員與海德堡大學的名譽教授，他解釋：「海德堡大學的離子探針對於硫氧同位素所測得的高解析度結果，是我們做出這項結論的關鍵。」藉由此離子探針，他們可以用百萬分之一的精準度來測量許多同位素的比例與稀有元素的含量。
美因茲大學地球科學研究所的Denis
Scholz教授的專長是判定歷史上的氣候波動發生的年代，他主導了統計分析的部分。結果指出這份地球化學數據的年代可以對應至格陵蘭冰芯中之前一道成因不明的硫酸鹽峰值。「對於氣候與環境紀錄的定年來說，這兩份年代一致的數據是個重大突破，
因為在此之前，新仙女木冷化事件以前並沒有年代確切的時間標記，」海德堡大學地球科學與環境物理研究所的Sophie
Warken博士如此說明。她負責進行的研究是過去數千年的氣候變遷。
Warken博士表示判定出來的新年代，顯示拉赫湖火山噴發的時間比新仙女木冷期早了大概150年。「因此可以排除這場火山噴發與急遽的氣候變遷之間有因果關係，」這位海德堡大學的研究學者與論文第一作者如此解釋。從格陵蘭的冰芯辨識出硫酸鹽的峰值，也讓研究團隊可以對新仙女木期開始之際發生的氣候事件做出相關結論。新仙女木期是段為時1000年左右的冷期，在此之前，科學家一直不確定引發它的氣候變遷，究竟是同步發生於北大西洋地區和歐陸，或者是花費數十年甚至數百年的時間才從格陵蘭擴散至歐陸。「我們從結果推導出溫度大幅降低是同步發生的，意味著歐洲中部和北極的氣候之間有直接關聯，」Warken博士解釋。
這位地球科學家說研究結果也開創了新的角度來理解過去複雜的氣候關係。不只如此，Sophie Warken強調結果提供了堅實的基礎來更準確地預測氣候未來的發展。這篇研究是「陸上岩漿系統」聯合計畫的部分成果，該計畫由海德堡大學、法蘭克福大學與美茵茲大學共同執行，經費來源為萊茵蘭—普法爾茨州政府與其他單位。另外的經費來源包括了德國研究基金會與歐洲研究協會。研究成果發表於期刊《科學前緣》(Science Advances)。
Speleothem and
ice cores: Natural climate archives offer new insights into the climate history
of central Europe
The synchronization of data from two natural climate archives --
a speleothem from the Herbstlabyrinth Cave in Hesse (Germany) and ice cores
from Greenland -- offers new insights into the chronology of abrupt climate
changes in Central Europe. According to the analysis, the devastating eruption
of the Laacher See volcano in what is now Rhineland-Palatinate occurred earlier
than previously assumed and hence could not have triggered the sudden-onset
cold period of approximately 13,000 years ago. Research by geoscientists from
Heidelberg University and Mainz University has confirmed this finding. Along
with precisely dating the volcanic eruption, the research team also estimated
its climatic impact.
The last eruption of the
Laacher See volcano is considered to be one of the most devastating events of
the past two million years, with effects that reached as far as northern Italy,
Scandinavia, and Russia. Exactly when the eruption occurred and whether it was
directly connected to a sudden cold period termed the Younger Dryas has long
been a topic of scientific debate. A new temporal classification was undertaken
in 2021 using radiocarbon dating of tree trunks. The results suggest that the
volcanic eruption must have taken place 130 years earlier than previously
assumed. The research team from Heidelberg and Mainz were able to confirm this
new date using a speleothem from the Herbstlabyrinth Cave in Breitscheid,
Hesse.
Because a volcanic eruption is associated with high
sulfur emissions, this volcanic signal would also have to be present in the
speleothem. "The high-resolution sulfur and oxygen isotope measurements
taken by the ion probe in Heidelberg were pivotal in making this
determination," explains Prof. Dr Axel Schmitt, a researcher at Curtin
University in Perth (Australia) and honorary professor at Heidelberg
University. With the ion probe, it is possible to measure various isotope
ratios and trace elements at micrometer level.
The geochemical data could be synchronized with a
heretofore unattributed sulfate peak in Greenland ice cores. The statistical
analyses were performed under the direction of Prof. Dr Denis Scholz, an expert
in age determination of historical climate fluctuations at the Institute for
Geosciences at Mainz University. "This synchronization represents a
breakthrough for the dating of climate and environmental archives in that,
until now, no absolutely dated time marker before the Younger Dryas cooling was
known," states Dr Sophie Warken, who conducts research into the climatic
changes of past millennia at the Institutes of Earth Sciences and Environmental
Physics at Heidelberg University.
According to Dr Warken, the new age determination
shows that the eruption took place about 150 years prior to the Younger Dryas
cold period. "This therefore excludes a causal relationship between the
volcanic eruption and the abrupt change in climate," explains the Heidelberg
researcher and first author of the study. Identifying the sulphate spikes in
the Greenland ice cores allowed the research team to draw conclusions as to the
climatic events at the beginning of the Younger Dryas. Until now, it was
unknown whether the climatic changes associated with this approximately
1,000-year cold period arose simultaneously in the North Atlantic region and
Europe or whether it spread from Greenland to Central Europe over several
decades or even centuries. "Our results lead to the conclusion that a
significant drop in temperature occurred simultaneously, indicating that the
Central European and Arctic climates were directly linked," explains Dr
Warken.
The geoscientist adds
that the research results open up new perspectives for understanding complex
climatic relationships of the past. The results also offer a solid basis for
more precise predictions of future climate developments, as Sophie Warken emphasizes.
The research was part of the collaborative "Terrestrial Magmatic
Systems" (TeMaS) project carried out jointly by Heidelberg University,
Goethe University Frankfurt (Main) and Mainz University, with funding by the
state of Rhineland-Palatine, among others. Additional funding was provided by
the German Research Foundation and the European Research Council. The results
of the research were published in the journal "Science Advances."
原始論文：Sophie F.
Warken, Axel K. Schmitt, Denis Scholz, Andreas Hertwig, Michael Weber, Regina
Mertz-Kraus, Frederick Reinig, Jan Esper, Michael Sigl. Discovery of
Laacher See eruption in speleothem record synchronizes Greenland and central
European Late Glacial climate change. Science Advances, 2025;
11 (3) DOI: 10.1126/sciadv.adt4057
引用自：Heidelberg University. "Speleothem and ice
cores: Natural climate archives offer new insights into the climate history of
central Europe."
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