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原文:Alfred Wegener Institute新聞稿  王珮玲 譯

If you want to know how the climate will change in the future, you need to look at the past. By looking at the climate changes that took place thousands of years ago, we can improve predictions for future climate. Comparing layers in the ice-core samples and ocean sediments has allowed researchers to deduce e.g. how the average temperature on Earth has changed over time, and also how great the variability was. From the height of the last glacial period 21,000 years ago to our current interglacial period, the Earth has warmed by an average of five degrees Celsius. In view of future global warming, it’s vital for today’s global population to know whether temperatures will rise steadily, or whether there will be sudden, major fluctuations. The frequency of extreme events represents an essential benchmark for climate change adaptation measures, since, when it comes to flood protection, transport and building materials, we need to be prepared for the worst-case scenario, and not just for “average” changes.


To date it has been assumed that temperatures varied greatly during the last glacial, while the current interglacial was largely characterised by small temperature variations. This interpretation was based on water isotope data from central Greenland ice cores.


Researchers from the Alfred Wegener Institute (AWI), Helmholtz Centre for Polar and Marine Research in Potsdam Germany compared the Greenland data with that from sediments collected in several ocean regions around the globe, as well as from ice-core samples gathered in Antarctica. Dr. Sze Ling Ho, who is currently a faculty member at the Institute of Oceanography NTU, contributed to the study by establishing the marine database. Together with climate and ice-core scientists, they have for the first time gathered and compared data from diverse climate archives and a total of 99 research sites. In the climate research community, ice cores are generally considered the gold standard, because their layers are highly consistent, unlike sediment layers from the seafloor, which are frequently marred by tectonic shifts, currents or marine organisms. They have devised mathematical methods that allow them to estimate the uncertainties and potential sources of error while assessing various paleoclimate archives, and to take these factors into account in their analyses. As such, they can compare the sediment samples with the ice cores for various epochs in the planet’s history.

德國波茨坦阿爾弗雷德·魏格納研究所 (Alfred Wegener Institute, AWI) 的研究團隊將格陵蘭的資料與收集自全球海域的海洋沉積物及南極冰芯樣本做比較。現為臺大海洋研究所助理教授的賀詩琳博士在團隊中致力於建立海洋的資料庫,她與其他氣候及冰芯科學家合作,首次蒐集並比較了總共99個研究地點中的多樣氣候指標資料。由於冰芯的層序不易受擾動且記錄具有較高的一致性,不像海床沉積物可能受到板塊移動、海流或海洋生物破壞,因此冰芯普遍被認為是氣候研究中的最為正確的記錄。根據這些資料,研究團隊建構數學方法來估計古氣候指標的不確定性及可能誤差來源,並進一步比較地球歷史中不同時代的沉積物與冰芯樣本。

They demonstrate that the phenomenon of major temperature fluctuations during glacial periods has by no means manifested uniformly worldwide, but has instead varied from region to region. For instance, in the Tropics the temperature variations were three times as intense as today at the height of the last glacial, whereas the ice cores from Greenland indicate variations that were 70 times as intense, suggesting that the conclusions regarding Greenland aren’t always representative of the entire world.


The more intensive variations during glacial periods are due to the greater difference in temperature between the ice-covered polar regions and the Tropics, which produced a more dynamic exchange of warm and cold air masses. Therefore, the variations will plausibly continue to lessen as global warming progresses, simply because the difference in temperature between the warming North and the Tropics will decline. However, data from this study cover timeframes spanning centuries and millennia, thus they can’t zoom in on just a handful of years, which means they can only draw indirect conclusions regarding the extreme events that shape weather.


Climate modellers had previously postulated the mechanism of reduced variability under warmer climatic conditions in 2014 (Schneider et al, 2015 https://doi.org/10.1175/JCLI-D-14-00632.1). Yet with their analysis, the AWI researchers are the first to reinforce this theory with global climate data from the past. In future, they plan to investigate in detail the changes in short-term variations in the past and their relation to long-term climate changes. To do so, they need reliable climate archives, and to improve the understanding of how they work. Increasing the accuracy to a level at which paleo-archives can also reflect extreme events will likely be one of the greatest challenges for the years to come.

氣候模擬學家曾提出在氣候變暖的情況下溫度變動減低的機制(Schneider等人, 2015年),根據他們的分析,AWI的研究人員首次利用過去的全球氣候資料來強化這項理論。未來,研究團隊計畫將檢視短時間尺度變化的細節,以及其與長時間氣候變遷的關聯。這項工作需要更可信的氣候記錄,因此提高古氣候記錄的準度使其能夠反映極端事件,可能是他們未來幾年來最大的挑戰之一。

(Modified from press release from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research https://www.awi.de/nc/en/about-us/service/press/press-release/klimaschwankungen-in-vergangenheit-und-zukunft.html)



Original publication:

Kira Rehfeld, Thomas Münch, Sze Ling Ho and Thomas Laepple: Global patterns of declining temperature variability from Last Glacial Maximum to Holocene (Nature, DOI: 10.1038/nature25454).


Kira Rehfeld, Thomas Münch, Sze Ling Ho and Thomas Laepple: Global patterns of declining temperature variability from Last Glacial Maximum to Holocene (Nature, DOI: 10.1038/nature25454).