Global Carbon Budget 2019
Global Carbon Budget 2019
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DOI：
10.5194/essd-11-1783-2019
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发表时间：
2019-12-04
影响因子：
11.4
通讯作者：
Zaehle, Sonke
中科院分区：
文献类型：
--
作者：
Friedlingstein, Pierre;Jones, Matthew W.;Zaehle, Sonke
准确评估人为二氧化碳(CO2)排放及其在大气、海洋和陆地生物圈之间的重新分配--“全球碳预算”--对于更好地理解全球碳循环、支持气候政策的制定和预测未来的气候变化非常重要。在这里，我们描述了量化全球碳预算的五个主要组成部分及其不确定性的数据集和方法。化石二氧化碳排放量(E-FF)基于能源统计数据和水泥生产数据，而土地利用变化排放量(E-LUC)，主要是砍伐森林，基于土地利用和土地利用变化数据和簿记模型。直接测量大气CO2浓度，并根据浓度的年变化计算其增长率(G(Atm))。利用带观测约束的全球过程模式估算了海洋CO2汇(S-海洋)和陆地CO2汇(S-陆地)。由此产生的碳收支失衡(B-IM)，即估计的总排放量与大气、海洋和陆地生物圈的估计变化之间的差额，是对当代碳循环的不完善数据和理解的衡量标准。所有不确定性均报告为+/-1西格玛。在过去十年(2009年至2018年)，E-FF9.5+/-0.5GTC yr1，E-LUC 1.5+/-0.7GTC yr 1，G(ATM)4.9+/-0.02GTC yr(-1)(2.3+/-0.01ppm yr(-1))，S-Ocean 2.5+/-0.6GTC yr(-1)，S-LAND 3.2+/-0.6GTC yr(-1)，预算失衡B-IM为0.4GTC Yr(-1)，表明高估了排放量和/或低估了汇。仅就2018年而言，E-FF的增长约为2.1%，化石排放量增加到10.0+/-0.5GTC年1，历史上首次达到10GTC年(-1)，E-LUC为1.5+/-0.7GTC年(-1)，人为二氧化碳排放总量为11.5+/-0.9GTC年(-1)(42.5+/-3.3 GtCO(2))。同样在2018年，G(ATM)为5.1+/-0.2GTC年(-1)(2.4+/-0.1ppm年(-1))，S-海洋为2.6+/-0.6GTC年(-1)，S-LAND为3.5+/-0.7GTC年(-1)，B-IM为0.3GTC。2018年全球大气二氧化碳浓度平均达到407.38+/-0.1ppm。2019年前6-10个月的初步数据显示，基于中国、美国、欧盟和印度的国家排放预测，以及对世界其他地区国内生产总值(GDP)最近碳强度变化的修正，E-FF增长率下降了+0.6%(范围为-0.2%至1.5%)。总体而言，在1959-2018年期间，全球碳预算五个组成部分的平均值和趋势是一致估计的，但在表示二氧化碳通量的半十年变异性方面，差异一直存在，最高可达1GTC yr(-1)。单个估计值之间的详细比较和广泛观测的引入表明：(1)过去十年土地利用变化排放的平均值和趋势没有达成共识，(2)不同方法之间对北部外热带陆地CO2通量大小的一致程度持续较低，以及(3)热带以外海洋模型对CO2变异性的明显低估。这一活生生的数据更新记录了新的全球碳预算中使用的方法和数据集的变化，以及与该数据集以前的出版物(Le Quere等人，2018a，b，2016,2015a，b，2014,2013)相比，在理解全球碳循环方面取得的进展。
Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere - the "global carbon budget" - is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe data sets and methodology to quantify the five major components of the global carbon budget and their uncertainties. Fossil CO2 emissions (E-FF) are based on energy statistics and cement production data, while emissions from land use change (E-LUC), mainly deforestation, are based on land use and land use change data and bookkeeping models. Atmospheric CO2 concentration is measured directly and its growth rate (G(ATM)) is computed from the annual changes in concentration. The ocean CO2 sink (S-OCEAN) and terrestrial CO2 sink (S-LAND) are estimated with global process models constrained by observations. The resulting carbon budget imbalance (B-IM), the difference between the estimated total emissions and the estimated changes in the atmosphere, ocean, and terrestrial biosphere, is a measure of imperfect data and understanding of the contemporary carbon cycle. All uncertainties are reported as +/- 1 sigma. For the last decade available (2009-2018), E-FF was 9.5 +/- 0.5 GtC yr 1, E-LUC 1.5 +/- 0.7 GtC yr 1, G(ATM) 4.9 +/- 0.02 GtC yr(-1) (2.3 +/- 0.01 ppm yr(-1)), S-OCEAN 2.5 +/- 0.6 GtC yr(-1), and S-LAND 3.2 +/- 0.6 GtC yr(-1), with a budget imbalance B-IM of 0.4 GtC yr(-1) indicating overestimated emissions and/or underestimated sinks. For the year 2018 alone, the growth in E-FF was about 2.1% and fossil emissions increased to 10.0 +/- 0.5 GtC yr 1, reaching 10 GtC yr(-1) for the first time in history, E-LUC was 1.5 +/- 0.7 GtC yr(-1), for total anthropogenic CO2 emissions of 11.5 +/- 0.9 GtC yr(-1) (42.5 +/- 3.3 GtCO(2)). Also for 2018, G(ATM) was 5.1 +/- 0.2 GtC yr(-1) (2.4 +/- 0.1 ppm yr(-1)), S-OCEAN was 2.6 +/- 0.6 GtC yr(-1), and S-LAND was 3.5 +/- 0.7 GtC yr(-1), with a B-IM of 0.3 GtC. The global atmospheric CO2 concentration reached 407.38 +/- 0.1 ppm averaged over 2018. For 2019, preliminary data for the first 6-10 months indicate a reduced growth in E-FF of +0.6% (range of -0.2% to 1.5 %) based on national emissions projections for China, the USA, the EU, and India and projections of gross domestic product corrected for recent changes in the carbon intensity of the economy for the rest of the world. Overall, the mean and trend in the five components of the global carbon budget are consistently estimated over the period 1959-2018, but discrepancies of up to 1 GtC yr(-1) persist for the representation of semi-decadal variability in CO2 fluxes.A detailed comparison among individual estimates and the introduction of a broad range of observations shows (1) no consensus in the mean and trend in land use change emissions over the last decade, (2) a persistent low agreement between the different methods on the magnitude of the land CO2 flux in the northern extra-tropics, and (3) an apparent underestimation of the CO2 variability by ocean models outside the tropics. This living data update documents changes in the methods and data sets used in this new global carbon budget and the progress in understanding of the global carbon cycle compared with previous publications of this data set (Le Quere et al., 2018a, b, 2016, 2015a, b, 2014, 2013).