Collaborative Research: P2C2--Exploring the Early Anthropogenic Hypothesis

提供资金以进一步测试早期人为假设（EAH），即农业产生的温室气体排放量足以扭转数千年前二氧化碳和甲烷浓度的自然下降趋势，通过推动大气中这两种气体的水平上升并保持气候异常温暖。具体而言，研究人员计划：（1）重新检查人为限制积雪厚度的模型参数化，以确定这种限制如何影响永久积雪的范围;（2）使用现代日照但改变二氧化碳和甲烷水平的模型模拟，以确定当今冰川开始的阈值;（3）收集现代和小冰期山地冰川和冰盖的数据，与模型模拟进行比较;（4）收集南亚水稻灌溉和牲畜饲养传播的考古学数据;（5）使用NCAR CCSM 4模型进行实验，包括：（a）“非人为”实验，利用具有二氧化碳生理学和动态海洋的相互作用的植被，评估早期农业温室气体的全面气候影响;（B）模拟工业化前晚期的实验，以区分早期农业与工业时代人为气体的气候影响;以及（c）一项仅使用人类直接输入的二氧化碳和甲烷的实验，以确定来自海洋的二氧化碳反馈是否可以解释支持35-这项研究具有潜在的变革性，因为它提供了一个关于气候强迫的新视角，并挑战了更广泛的科学界对人类对气候影响程度的理解。该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。

Funding is provided to further test the early anthropogenic hypothesis (EAH) that agriculture produced greenhouse-gas emissions large enough to reverse natural downward trends in carbon dioxide and methane concentrations several thousand years ago by driving atmospheric levels of both gases upward and keeping the climate anomalously warm.Specifically, the researchers plan to: (1) re-examine a model parameterization that artificially limit snow thickness, in order to determine how this constraint affects the extent of permanent snow cover; (2) run model simulations with modern insolation but varying carbon dioxide and methane levels to determine the threshold for present-day glacial inception; (3) assemble data on modern and little ice age mountain glaciers and ice caps for comparison to the model simulations; (4) assemble archeological data on the spread of rice irrigation and livestock tending across southern Asia; and (5) conduct experiments with the NCAR CCSM4 model that include: (a) a 'no anthro' experiment using interactive vegetation with carbon dioxide physiology and a dynamical ocean to assess the full climatic impact of early agricultural greenhouse gases; (b) an experiment simulating late pre-industrial times in order to parcel out the climatic effects of early-agricultural versus industrial-era anthropogenic gases; and (c) an experiment using only direct carbon dioxide and methane inputs from humans to determine whether carbon dioxide feedbacks from the ocean can account for the full carbon budget needed to support a 35-40 parts per million atmospheric carbon dioxide anomaly.This research is potentially transformative because it provides a new perspective on climate forcing and challenges the broader science community's understanding of the extent of human impacts on climate. This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).