Estimates of Pliocene Tropical Pacific Temperature Sensitivity to Radiative Greenhouse Gas Forcing
Estimates of Pliocene Tropical Pacific Temperature Sensitivity to Radiative Greenhouse Gas Forcing
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DOI：
10.1029/2018pa003461
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发表时间：
2019-01
影响因子：
3.5
通讯作者：
H. L. Ford;A. Ravelo
中科院分区：
文献类型：
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作者：
H. L. Ford;A. Ravelo
西赤道太平洋暖池表面温度>28 °C，具有深厚的温跃层，是全球气候系统潜热和感热的重要来源。由于热带地区对冰-冰反馈不敏感，WEP对辐射强迫的响应可以用来限制地球系统敏感性的最小估计。pCO 2-辐射变暖预测的气候模拟显示WEP变率几乎没有变化;在这里，我们使用单个地表和地下居住化石有孔虫的温度分布来评估过去的变率以及上新世更新世可能的辐射和动力气候强迫。我们研究了WEP暖池变化在成对的冰期-间冰期（IG）间隔四次：全新世末次冰期最大，~2，~3，和~4 Ma。我们的结果表明，这些表面和次表面温度分布对于所有IG对都是相似的，表明即使pCO 2辐射强迫和其他边界条件在IG时间尺度上发生变化，变化也没有变化。上新世-更新世海表温度（SST）分布与全新世相似，表明WEP SST响应于pCO 2辐射强迫和相关反馈。相比之下，上新世更新世地下温度分布表明地下温度对温跃层温度和深度的变化做出反应。我们使用我们的个体有孔虫SST数据集和先前发表的基于硼同位素的高分辨率pCO 2重建来估计上新世中期（~3 Ma）的热带温度敏感性。我们发现热带温度敏感性等于或小于晚更新世。
The Western Equatorial Pacific (WEP) warm pool, with surface temperatures >28 °C and a deep thermocline, is an important source of latent and sensible heat for the global climate system. Because the tropics are not sensitive to ice‐albedo feedbacks, the WEP's response to radiative forcing can be used to constrain a minimum estimate of Earth system sensitivity. Climate modeling of pCO2‐radiative warming projections shows little change in WEP variability; here we use temperature distributions of individual surface and subsurface dwelling fossil foraminifera to evaluate past variability and possible radiative and dynamic climate forcing over the Plio‐Pleistocene. We investigate WEP warm pool variability within paired glacial‐interglacial (G‐IG) intervals for four times: the Holocene‐Last Glacial Maximum, ~2, ~3, and ~4 Ma. Our results show that these surface and subsurface temperature distributions are similar for all G‐IG pairs, indicating no change in variability, even as pCO2‐radiative forcing and other boundary conditions changed on G‐IG timescales. Plio‐Pleistocene sea surface temperature (SST) distributions are similar to those from the Holocene, indicating WEP SSTs respond to pCO2‐radiative forcing and associated feedbacks. In contrast, Plio‐Pleistocene subsurface temperature distributions suggest subsurface temperatures respond to changes in thermocline temperature and depth. We estimate tropical temperature sensitivity for the mid‐Pliocene (~3 Ma) using our individual foraminifera SST data set and a previously published high‐resolution boron isotope‐based pCO2 reconstruction. We find tropical temperature sensitivity was equal to, or less than, that of the Late Pleistocene.