Seasonal origin of the thermal maxima at the Holocene and the last interglacial
Seasonal origin of the thermal maxima at the Holocene and the last interglacial
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DOI：
10.1038/s41586-020-03155-x
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发表时间：
2021-01-28
期刊：
影响因子：
64.8
通讯作者：
Yan, Mi
中科院分区：
文献类型：
--
作者：
Bova, Samantha;Rosenthal, Yair;Yan, Mi
海洋沉积物岩心的代用重建表明，最后一次和当前间冰期（全新世时期的最高温度，10，000年至6，000年前，以及最后一次间冰期，128，000年至123，000年前）的前半部分温度可以说超过了现代的温暖（1-3）。相比之下，气候模式模拟了整个两个时期的单调变暖（4-7）。这种巨大的模型数据差异破坏了对代用重建和气候模型的信心，并抑制了对近期气候变化的机械理解。在这里，我们表明，以前的全球重建的温度在全新世（1-3）和末次间冰期（8）反映了季节性的演变，而不是每年的温度，我们开发了一种方法，将它们转换为平均年温度。我们进一步证明，自全新世开始（约12，000年前）以来，全球年平均海面温度一直在稳步上升，首先是对冰盖退缩（12，000年至6，500年前）的反应，然后是温室气体浓度上升（在过去6，500年左右的时间里为0.25 +/- 0.21摄氏度）。然而，在最后一次间冰期的年平均温度是稳定的，比估计的温度在全新世温暖，我们把这归因于接近恒定的温室气体水平和冰盖的减少程度。因此，我们认为，全新世的气候不同于最后一个间冰期在两个方面：第一，更大的残留冰川冰盖的作用，以冷却全新世早期，第二，在全新世晚期温室气体水平上升温暖了地球。此外，我们的重建表明，现代全球温度已经超过了过去12，000年的年度水平，可能接近末次间冰期（128，000至115，000年前）的温暖程度。
Proxy reconstructions from marine sediment cores indicate peak temperatures in the first half of the last and current interglacial periods (the thermal maxima of the Holocene epoch, 10,000 to 6,000 years ago, and the last interglacial period, 128,000 to 123,000 years ago) that arguably exceed modern warmth(1-3). By contrast, climate models simulate monotonic warming throughout both periods(4-7). This substantial model-data discrepancy undermines confidence in both proxy reconstructions and climate models, and inhibits a mechanistic understanding of recent climate change. Here we show that previous global reconstructions of temperature in the Holocene(1-3) and the last interglacial period(8) reflect the evolution of seasonal, rather than annual, temperatures and we develop a method of transforming them to mean annual temperatures. We further demonstrate that global mean annual sea surface temperatures have been steadily increasing since the start of the Holocene (about 12,000 years ago), first in response to retreating ice sheets (12 to 6.5 thousand years ago), and then as a result of rising greenhouse gas concentrations (0.25 +/- 0.21 degrees Celsius over the past 6,500 years or so). However, mean annual temperatures during the last interglacial period were stable and warmer than estimates of temperatures during the Holocene, and we attribute this to the near-constant greenhouse gas levels and the reduced extent of ice sheets. We therefore argue that the climate of the Holocene differed from that of the last interglacial period in two ways: first, larger remnant glacial ice sheets acted to cool the early Holocene, and second, rising greenhouse gas levels in the late Holocene warmed the planet. Furthermore, our reconstructions demonstrate that the modern global temperature has exceeded annual levels over the past 12,000 years and probably approaches the warmth of the last interglacial period (128,000 to 115,000 years ago).