Response of Central European SST to atmospheric pCO2 forcing during the Oligocene – A combined proxy data and numerical climate model approach
Response of Central European SST to atmospheric pCO2 forcing during the Oligocene – A combined proxy data and numerical climate model approach
复制标题
DOI：
10.1016/j.palaeo.2016.07.033
复制
发表时间：
2016-10
期刊：
影响因子：
--
通讯作者：
E. Walliser;Gerrit Lohmann;I. Niezgodzki;T. Tütken;B. Schöne
中科院分区：
文献类型：
--
作者：
E. Walliser;Gerrit Lohmann;I. Niezgodzki;T. Tütken;B. Schöne
二氧化碳引起的全球变暖将影响季节至年代际温度模式。预期的变化在温带地区将特别强烈，那里的气温上升速度将快于低纬度地区。尽管如此，在一个普遍变暖的世界，特别是在温带近岸地表水，即许多人类社会所依赖的海洋中生态最丰富的地区，短期气候动态究竟会发生怎样的变化，目前仍然知之甚少。具体来说，详细了解二氧化碳和季节性海温之间的关系对于理解海洋和大气之间的相互作用至关重要。在目前的研究中，我们首次研究了中渐新世（约31至25 Ma）期间，大气中二氧化碳水平的上升如何迫使中欧（古纬度~ 45°N）的地表温度变化，在这段地球历史时间间隔中，全球条件与未来几个世纪的预测相当。为此，我们计算了渐新世（冬季、夏季、年平均值）的数值气候模式，假设大气二氧化碳分别从400 ppm上升到560ppm（当前水平为工业化前水平PAL的两倍）和从400 ppm上升到840ppm（= 3倍PAL）。这些模型与双壳类化石（Glycymeris planicostalis，G.）的δ18O值重建的季节分辨海表温度（SST）进行了比较。鲨鱼牙齿（Carchariascuspidata，C.）；从美因茨和卡塞尔盆地（德国）的浅水沉积物中采集的一种鱼。基于多分类单元的氧同位素重建表明，表层水（30 ~ 40米以上）的温度逐渐上升，在鲁伯利期平均上升4°C，随后在Chattian期下降4°C。在鲁伯利期最温暖的时间间隔内，季节温度幅值增加了约2°C，夏季（5°C）的变暖比冬季（3°C）更为明显。根据数值气候模拟，渐新世早期地表水的变暖需要二氧化碳至少增加160 ppm，即400 ppm至560 ppm。考虑到在不久的将来预测的大气二氧化碳水平可能会大大超过这个值，早渐新世的变暖暗示了二氧化碳水平升高下中欧未来可能的气候。
CO2-induced global warming will affect seasonal to decadal temperature patterns. Expected changes will be particularly strong in extratropical regions where temperatures will increase at faster rates than at lower latitudes. Despite that, it is still poorly constrained how precisely short-term climate dynamics will change in a generally warmer world, particularly in nearshore surface waters in the extratropics, i.e., the ecologically most productive regions of the ocean on which many human societies depend. Specifically, a detailed knowledge of the relationship betweenpCO2and seasonal SST is crucial to understand interactions between the ocean and the atmosphere. In the present investigation, we have studied for the first time how rising atmosphericpCO2levels forced surface temperature changes in Central Europe (paleolatitude ~ 45 °N) during the mid-Oligocene (from ca. 31 to 25 Ma), a time interval of Earth history during which global conditions were comparable to those predicted for the next few centuries. For this purpose, we computed numerical climate models for the Oligocene (winter, summer, annual average) assuming an atmospheric carbon dioxide rise from 400 to 560 ppm (current level to two times pre-industrial levels, PAL) and from 400 to 840 ppm (= three times PAL), respectively. These models were compared to seasonally resolved sea surface temperatures (SST) reconstructed from δ18O values of fossil bivalve shells (Glycymeris planicostalis,G. obovata,Palliolum pictum,Arctica islandicaandIsognomon maxillata sandbergeri) and shark teeth (Carchariascuspidata,C. acutissimaandPhysogaleus latus) collected from the shallow water deposits of the Mainz and Kassel Basins (Germany). Multi-taxon oxygen isotope-based reconstructions suggest a gradual rise of temperatures in surface waters (upper 30 to 40 m), on average, by as much as 4 °C during the Rupelian stage followed by a 4 °C cooling during the Chattian stage. Seasonal temperature amplitudes increased by ca. 2 °C during the warmest time interval of the Rupelian stage, with warming being more pronounced during summer (5 °C) than during winter (3 °C). According to numerical climate simulations, the warming of surface waters during the early Oligocene required a CO2increase by at least 160 ppm, i.e., 400 ppm to 560 ppm. Given that atmospheric carbon dioxide levels predicted for the near future will likely exceed this value significantly, the Early Oligocene warming gives a hint of the possible future climate in Central Europe under elevated CO2levels.