Collaborative Research: Arctic Temperature Amplification during the Middle Pliocene (ArcAMP): Assessing the interaction among feedback mechanisms

北极目前变暖的速度比地球上其他任何地方都快。这种所谓的北极放大地表温度是有充分证据的；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)，可能会找到解决与北极放大有关的一些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约400ppm的浓度相当，而北极温度却高出10至20摄氏度。该项目调查了上新世期间陆地反馈机制之间的相互作用，以及它们在放大北极表面温度方面的作用。特别是，它调查了植被反照率、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。这将通过对三个北极高地的过去温度、大气二氧化碳和火焰进行高分辨率重建来实现，这些地点最近已经被陆地宇宙成因核素测得很好的年代。为了弄清这些过程可能是如何相互作用放大北极温度的，将使用共同体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.