Collaborative Research: Arctic Temperature Amplification during the Middle Pliocene (ArcAMP): Assessing the Interaction Among Feedback Mechanisms

北极目前的变暖速度比地球上任何地方都要快。这种所谓的北极表面温度放大是有充分记录的；然而，各种反馈机制以及它们如何合作放大北极温度仍然不确定。在上新世（260万至530万年前）可能会找到解决这些关于北极放大的基本气候问题的重要线索，这是地球历史上最后一次大气二氧化碳浓度与现代浓度相当，约为400ppm，但北极温度比现在高10至20摄氏度。本项目研究了上新世陆地反馈机制之间的相互作用及其在放大北极表面温度中的作用。特别地，它研究了植被反照率、大气水蒸气和火灾排放的黑碳对北极气候系统的净辐射强迫。这将通过对三个高北极地区的过去温度、大气二氧化碳和火灾进行高分辨率重建来完成，这些地点最近已经被地球宇宙核素确定了年代。为了弄清楚这些过程是如何相互作用而放大北极温度的，将使用社区地球系统模型进行一系列气候实验。

The Arctic is currently warming faster than anywhere else on Earth. This so-called Arctic Amplification of surface temperatures is well documented; however, the various feedback mechanisms and how they co-operate to amplify arctic temperatures remain uncertain. Important clues for solving some of these fundamental climate questions regarding arctic amplification may be found during the Pliocene (2.6 to 5.3 million years ago), which is the last time in Earth's history when atmospheric CO2 concentrations were comparable to modern concentrations of about 400 ppm, and yet arctic temperatures were 10 to 20 degrees C warmer. This project investigates the interactions among terrestrial feedback mechanisms during the Pliocene and their role in amplifying arctic surface temperatures. In particular, it investigates the net radiative forcing of vegetation albedo, atmospheric water vapor, and black carbon emitted from fire on the arctic climate system. This will be accomplished by conducting high-resolution reconstructions of past temperatures, atmospheric CO2, and fire for three high arctic sites that have been recently well-dated by terrestrial cosmogenic nuclides. To disentangle how these processes may have been interacting to amplify arctic temperatures, a series of climate experiments will be conducted using the Community Earth System Model.