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全球碳循环研究计划强调两个基本问题。第一个是关于碳系统对人为扰动的直接响应,即化石燃烧和土地利用变化排放出的过多的CO_2如何分布在大气、陆地和海洋中,以及这种分布如何随时间而变化?第二个问题是反馈问题,即气候变化如何反过来影响自然界碳循环并导致大气CO_2浓度的变化?本文评述解决这些问题的观测约束条件:①记录最近100年来CO_2浓度增加的大气直接观测和冰芯测量;②用观察氧和碳同位素的新方法和模型模拟都得到当前大气CO_2的收支估值,在此估值中海洋的作用如何?③通过CO_2全球监测网揭示的空间分布信息。100年前Arrhenius与他的同事(地质学家Hogbom)都注意到了控制大气中CO_2浓度的主要过程,然而他们的兴趣在于长期特征而没有察觉工业排放对全球气候的直接威胁。今天,我们能够定量确定和模拟人为扰动的直接影响,尽管大量不确定因素依然存在,特别是在地球生物圈过程方面。然而,我们对许多碳循环气候反馈的理解还是很有限的,这个问题在未来几十年里将始终是一个具有挑战性的课题。
The Global Carbon Cycle Research Program emphasizes two basic issues. The first is a direct response to anthropogenic disturbances of the carbon system, ie, how is excess CO 2 emitted from fossil fuel combustion and land-use changes distributed over the atmosphere, land and oceans and how this distribution varies over time? The questions are the feedback problem, that is, how climate change in turn affects the carbon cycle in the natural world and leads to the change of atmospheric CO 2 concentration. This paper reviews the observation constraints for solving these problems: ① direct observations of the atmospheric CO 2 concentration and ice core measurements ; ② The current estimation of the CO 2 budget is based on new methods and modeling of oxygen and carbon isotope observations. What is the role of the oceans in this valuation? ③ Spatial distribution information revealed through the CO_2 Global Monitoring Network. 100 years ago Arrhenius and his colleague Hogbom both noticed the main process of controlling CO 2 concentration in the atmosphere. However, their interest was in long-term characteristics without the direct threat of industrial emissions to the global climate. Today, we can quantify and simulate the direct effects of anthropogenic disturbance quantitatively, albeit with a large number of uncertainties, especially in the Earth’s biosphere process. However, our understanding of many of the carbon cycle climate feedbacks is still limited and will remain a challenging issue for decades to come.