Collaborative Research: Testing Early Anthropogenic Effects on Climate

该奖项支持使用一般循环模型的研究，以验证自大约11,000年前出现管理农业以来人类所进行的活动已向地球大气中增加了大量二氧化碳（CO2）和甲烷的观点。研究人员将尝试模拟一个没有工业化前和工业化时代温室气体排放的更冷的世界。研究人员还将研究在工业化时期之前大规模砍伐欧亚森林的影响，并分析在一个更冷、温室气体浓度更低的世界中短期气候变化的影响。作者最近发表的研究表明，大约11000年前人类的活动向大气中增加了大量的二氧化碳和甲烷。人类大量排放这些气体的开始可以通过大气中气体浓度偏离已经存在了数千年的自然循环变化来检测。研究人员假设，如果二氧化碳和甲烷的自然减少在全新世中后期盛行，大气中的温室气体浓度将下降到其自然极限，地球将是一个比现在冷得多的地方。一项证据表明，今天加拿大东北部的冰盖正在扩大。这表明，工业化前人类活动的温室气体排放使气候过于温暖，导致冰川无法开始。

This award supports research using general circulation models to test the idea that activities undertaken by humans since the advent of managed agriculture approximately 11,000 years ago have added significant amounts of carbon dioxide (CO2) and methane into the Earth's atmosphere. The researchers will attempt to simulate a cooler world that would exist today in the absence of pre-industrial and industrial-era greenhouse emissions. The researchers will also examine the impacts of large-scale clearance of Eurasian forests prior to industrial periods and analyze the impact of short-term climatic variations in a cooler and lower greenhouse gas concentration world. Recently published research by the authors suggests that activities undertaken by humans about 11,000 years ago have added significant amounts of carbon dioxide and methane to the atmosphere. The onset of significant human emissions of these gases can be detected by the departure of atmospheric gas concentrations from natural cyclic variations that have prevailed for thousands of years.The researchers hypothesize that if natural decreases in CO2 and methane prevailed during the middle and late Holocene, greenhouse-gas concentrations in the atmosphere would have fallen toward their natural limit and the Earth would be a considerably cooler place than it is today. One line of evidence suggests an ice sheet would be growing today in northeast Canada. This suggests that greenhouse-gas emissions from pre-industrial human activities kept climate too warm for glaciation to begin.