CMIP5模式对未来升温情景下全球陆地生态系统净初级生产力变化的预估

doi:10.12006/j.issn.1673-1719.2017.042

摘要/Abstract

摘要：

针对《巴黎协定》提出的温控目标,利用耦合模式比较计划第五阶段（CMIP5）模式在RCP2.6、RCP4.5和RCP8.5情景下的模拟结果,初步分析了全球升温情景下陆地生态系统净初级生产力（NPP）相对于参考时段（1986—2005年）的变化,重点分析了1.5℃和2℃升温时NPP相对于参考时段的变化量,并探讨了大气CO₂浓度、气温、降水和辐射的变化及其对NPP变化的影响。CMIP5基于各典型浓度路径模拟的全球陆地生态系统NPP均呈增加趋势,且NPP增加量与升温幅度成正比。在相同的升温幅度下,基于各典型浓度路径模拟的各环境因子和NPP的变化量较为一致。陆地生态系统NPP总量增加主要由大气CO₂浓度上升驱动,其他环境因子的影响相对较弱。中国东南部、非洲中部、美国东南部和亚马孙雨林西部地区NPP增加最明显。NPP变化量的空间格局主要由大气CO₂浓度增加和升温控制,降水和辐射的影响相对较小。具体而言,大气CO₂浓度上升对中低纬度的NPP变化贡献最大,对北方高纬度地区NPP变化贡献较小。温度上升有利于促进北方高纬度地区和青藏高原地区NPP,但对中低纬度地区的NPP有较强的抑制作用。鉴于既有典型浓度路径和地球系统模型的限制,本文对未来升温情景下陆地生态系统NPP的预估仍存在较大的不确定性,需要在未来的研究中进一步改进。

关键词: 净初级生产力（NPP), 全球变暖, CMIP5, 典型浓度路径, 大气CO₂浓度

Abstract:

We tentatively analyzed differences between global terrestrial net primary productivity (NPP) under global warming by the targeting temperature of the Pairs Agreement and that during 1986-2005. We addressed the changes in global terrestrial NPP, changes inrelating environmental factors (atmospheric CO₂ concentration, temperature, precipitation, and radiation), and their contribution to the NPP changes under global warming of 1.5℃ and 2℃. The projected global terrestrial NPP increases in proportion to the warming magnitude based on the results from CMIP5 models that runs under the three representative concentration pathways (RCP2.6, RCP4.5 and RCP8.5). Changes in the projected environmental factors and NPP at given warming magnitude are generally consistent across the three RCPs. The increasing atmospheric CO₂ concentration is the dominant factor that drives the total amount of global terrestrial NPP, while the contributions of other environmental factors are relatively small. The most notable increases in NPP locate in southeast China, central Africa, southeast U.S. and western Amazonia. The spatial pattern of NPP changes are mainly controlled by atmospheric CO₂ concentration increase and warming, while precipitation and radiation contribute much fewer. The effects of increasing atmospheric CO₂ concentration on NPP are stronger at lower latitudes but weaker at northern high latitudes. Warming benefits ecosystem NPP at northern high latitudes and Tibetan Plateau but strongly depletes ecosystem NPP at lower latitudes. Our analyses of global terrestrial ecosystem NPP changes under future global warming scenarios still have significant uncertainties due to limitations of current RCPs and earth system models, which needs further refinements.

Key words: Net primary productivity (NPP), Global warming, CMIP5, RCP, Atmospheric CO₂ concentration

朱再春, 刘永稳, 刘祯, 朴世龙. CMIP5模式对未来升温情景下全球陆地生态系统净初级生产力变化的预估[J]. 气候变化研究进展, 2018, 14(1): 31-39.

Zai-Chun ZHU, Yong-Wen LIU, Zhen LIU, Shi-Long PIAO. Projection of changes in terrestrial ecosystem net primary productivity under future global warming scenarios based on CMIP5 models[J]. Climate Change Research, 2018, 14(1): 31-39.

图/表 5

表1 15个CMIP5地球系统模式的基本特征

Table 1 The characteristics of 15 CMIP5 models used in this study

图1 全球陆地生态系统NPP、大气CO2浓度、降水和辐射随全球升温的变化注：图中, 绿色、橙色和紫色数字分别代表RCP2.6、RCP4.5 和RCP8.5 情景下达到一定增温幅度（1.5℃、2℃、2.5℃和3℃）的年份。绿色、橙色和紫色阴影以及黑色误差条分别代表RCP2.6、RCP4.5 和RCP8.5 情景下CMIP5 各模式模拟结果的不确定性范围（标准差)。

Fig. 1 Changes in global terrestrial ecosystem NPP, atmospheric CO2concentration, precipitation and radiation with future global warming

图2 全球升温1.5℃时CMIP5模式在RCP2.6、RCP4.5和RCP8.5情景下预估的全球年总NPP、年均温度、年总降水、年均辐射相对于参考时段（1986—2005年）的变化量的空间分布注：白色区域是非植被区域,主要是沙漠和冰雪覆盖地区。

Fig. 2 Spatial pattern of changes in annual total NPP, annual mean temperature, annual total precipitation and annual mean down welling shortwave radiation under global warming of 1.5℃ relative to the reference period 1986 to 2005 based on CMIP5 simulations under RCP2.6, RCP4.5 and RCP8.5

图3 全球升温2℃时CMIP5模式在RCP2.6、RCP4.5和RCP8.5情景下预估的全球年总NPP、年均温度、年总降水、年均辐射相对于参考时段（1986—2005年）的变化量的空间分布

Fig. 3 Spatial pattern of changes in annual total NPP, annual mean temperature, annual total precipitation and annual mean down welling shortwave radiation under global warming of 2℃ relative to the reference period 1986 to 2005 based on CMIP5 simulations under RCP2.6, RCP4.5 and RCP8.5

图4 全球升温1.5℃和2℃时CMIP5在RCP2.6情景下预估的大气 CO2浓度、温度、降水和辐射对全球年总NPP变化量贡献的空间分布

Fig. 4 Spatial pattern of contribution of changes in atmospheric CO2 concentration, temperature, precipitation and down welling shortwave radiation to the changes in annual total NPP under global warming of 1.5℃ and 2℃ based on CMIP5 simulations under RCP2.6

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