Constraining carbon cycle processes over the last glacial cycle

人为气候变化是我们面临的最大全球环境挑战之一。我们燃烧化石燃料产生的排放物正在改变大气中的温室气体水平，使地球气候变暖。这一点很清楚--但从长远来看，地球将如何对这些排放作出反应仍存在相当大的不确定性。这种不确定性的主要来源之一是碳循环将如何应对更高水平的二氧化碳和气候变化。气候模式是研究气候变化的重要工具之一，然而，气候系统是复杂的，气候模式远非完美。我们可以通过比较气候模拟与过去气候和当前观测的重建来验证模拟的气候系统响应。从长远来看，一些最重要和最可靠的气候数据重建来自南极洲和格陵兰岛的冰芯。这些冰芯记录了温室气体的变化和几个冰川周期的气候代理。最近开发的复杂的气候-碳循环模型和数据重建的最后一个冰川周期提供了一个独特的机会，量化的重要性，气候-碳循环反馈在很长的时间尺度。

Anthropogenic climate change is one of the greatest global environmental challenges we face. The emissions we generate from burning fossil fuels are changing the levels of greenhouse gases in the atmosphere and warming the Earth's climate. This is clear - yet there is still considerable uncertainty in how the Earth will react to these emissions over the longer term. One of the major sources of this uncertainty is how the carbon cycle will respond, both to higher levels of carbon dioxide and to the changing climate. Climate models are one of the most important tools we have for studying climate change, however, the climate system is complex and climate models are far from perfect. We can validate the modelled climate system response by comparing climate simulations to reconstructions of past climate and current observations. Over the long-term, some of the most important and reliable climate data reconstructions come from ice cores in Antarctica and Greenland. These ice cores record changes in greenhouse gases and proxies for climate over several glacial cycles. Recently developed complex climate-carbon cycle models and data reconstructions over the last glacial cycle provide a unique opportunity to quantify the importance of climate-carbon cycle feedbacks over very long time scales.