Recent Greenhouse Gas Concentrations

Gases typically measured in parts per million (ppm), parts per billion (ppb) or parts per trillion (ppt) are presented separately to facilitate comparison of numbers. Global Warming Potentials (GWPs) and atmospheric lifetimes are from the Intergovernmental Panel on Climate Change (IPCC, 2013, Table 8.A.1), except for the atmospheric lifetime of carbon dioxide (CO2) which is explained in footnote 4. Additional material on greenhouse gases can be found in CDIAC's Reference Tools. To find out how CFCs, HFCs, HCFCs, and halons are named, see Name that compound: The numbers game for CFCs, HFCs, HCFCs, and Halons. Concentrations given apply to the lower 75-80 percent of the atmosphere, known as the troposphere. Sources of the current and preindustrial concentrations of the atmospheric gases listed in the table below are given in the footnotes. Investigators at the National Oceanic and Atmospheric Administration have provided the recent concentrations. Much of the data provided results from the work of various investigators at institutions other than CDIAC, and represent considerable effort on their part. We ask as a basic professional courtesy that you acknowledge the primary sources, indicated in the footnotes below, or in the links given in the footnotes. Concentrations of ozone and water vapor are spatially and temporally variable due to their short atmospheric lifetimes. A vertically and horizontally averaged water vapor concentration is about 5,000 ppm. Globally averaged water vapor concentration is difficult to measure precisely because it varies from one place to another and from one season to the next. This precludes a precise determination of changes in water vapor since pre-industrial time. However, a warmer atmosphere will likely contain more water vapor than at present. For a more detailed statement on water vapor from the National Oceanic and Atmospheric Administration, see the "water vapor" page at http://lwf.ncdc.noaa.gov/oa/climate/gases.html

以百万分比浓度（parts per million, ppm）、十亿分比浓度（parts per billion, ppb）或万亿分比浓度（parts per trillion, ppt）计量的气体均单独列示，以便于数值间的对比分析。全球增温潜势（Global Warming Potentials, GWPs）与大气寿命数据均来自政府间气候变化专门委员会（Intergovernmental Panel on Climate Change, IPCC，2013年，表8.A.1），仅二氧化碳（carbon dioxide, CO₂）的大气寿命详见脚注4。有关温室气体的补充资料可查阅二氧化碳信息分析中心（Carbon Dioxide Information Analysis Center, CDIAC）的参考工具栏目。若需了解氯氟烃（CFCs）、氢氟烃（HFCs）、氢氯氟烃（HCFCs）及哈龙（halons）的命名规则，请参阅《化合物命名：氯氟烃、氢氟烃、氢氯氟烃与哈龙的数字游戏》一文。本文所列浓度值均适用于占大气总量75%~80%的下层大气，即对流层（troposphere）。下表所列大气气体的当前浓度与工业化前浓度的来源详见各脚注。美国国家海洋和大气管理局（National Oceanic and Atmospheric Administration, NOAA）的科研人员提供了近期的浓度观测数据。本数据集的多数数据源自CDIAC以外多家科研机构的研究人员，凝聚了他们的大量科研心血。作为基本的学术礼仪，我们恳请您在使用时引用脚注中注明的原始数据源，或脚注中提供链接的相关资源。臭氧与水汽的大气寿命较短，因此其浓度存在显著的空间与时间异质性。全球垂直与水平平均的水汽浓度约为5000 ppm。由于水汽浓度随地域与季节持续变化，精准测定全球平均水汽浓度极具挑战，这也使得我们无法精准确定自工业化时代以来水汽浓度的变化幅度。不过，气温升高的大气大概率会比当前大气容纳更多水汽。如需查阅美国国家海洋和大气管理局关于水汽的详细说明，请访问http://lwf.ncdc.noaa.gov/oa/climate/gases.html页面的"水汽"栏目。