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

目前，北极变暖的速度比地球上任何其他地方都快。 这种所谓的北极表面温度放大现象有据可查;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。解决一些关于北极放大的基本气候问题的重要线索可能在上新世（260万至530万年前）发现，这是地球历史上最后一次大气中二氧化碳浓度与现代浓度相当，约为400 ppm，但北极温度高出10至20摄氏度。本项目研究上新世期间陆地反馈机制之间的相互作用及其在放大北极表面温度方面的作用。 特别是，它调查了净辐射强迫的植被CO2，大气水蒸气和黑碳排放的火灾对北极气候系统。这将通过对过去的温度，大气CO2和火灾进行高分辨率重建来实现，这三个高北极地区最近已经被陆地宇宙成因核素确定了日期。 为了解开这些过程如何相互作用以放大北极温度，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.