日本地球惑星科学連合2016年大会

講演情報

インターナショナルセッション(ポスター発表)

セッション記号 A (大気水圏科学) » A-CG 大気水圏科学複合領域・一般

[A-CG09] Development and application of land and ocean biogeochemistry components of Earth system models

2016年5月23日(月) 17:15 〜 18:30 ポスター会場 (国際展示場 6ホール)

コンビーナ:*河宮 未知生(海洋研究開発機構)、立入 郁(海洋研究開発機構)、羽島 知洋(独立行政法人 海洋研究開発機構)、アローラ ビベック(カナダ気候モデル解析センター)

17:15 〜 18:30

[ACG09-P07] On constraining the strength of the terrestrial CO2 fertilization effect in an Earth system model

*Vivek Arora1John Scinocca1 (1.Canadian Centre for Climate Modelling and Analysis, Environment and Climate Change Canada)

キーワード:Earth system models, CO2 fertilization effect, Land carbon uptake

Earth system models (ESMs) explicitly simulate the interactions between the physical climate system components and biogeochemical cycles. Physical and biogeochemical aspects of ESMs are routinely compared against their observation-based counterparts to assess model performance and to evaluate how this performance is affected by ongoing model development. Here, we assess the performance of version 4.2 of the Canadian Earth system model against four, land carbon cycle focused, observation-based determinants of the global carbon cycle and the historical global carbon budget over the 1850–2005 period. Our objective is to constrain the strength of the terrestrial CO2 fertilization effect which is known to be the most uncertain of all carbon cycle feedbacks. The observation-based determinants include (1) globally-averaged atmospheric CO2 concentration, (2) cumulative atmosphere–land CO2 flux, (3) atmosphere–land CO2 flux for the decades of 1960s, 1970s, 1980s, 1990s and 2000s and (4) the amplitude of the globally-averaged annual CO2 cycle and its increase over the 1980 to 2005 period. The optimal simulation that satisfies constraints imposed by the first three determinants yields a net primary productivity (NPP) increase from ~ 58 Pg C yr−1 in 1850 to about ~ 74 Pg C yr−1 in 2005; an increase of ~ 27 % over the 1850–2005 period. The simulated loss in the global soil carbon amount due to anthropogenic land use change over the historical period is also broadly consistent with empirical estimates. Yet, it remains possible that these determinants of the global carbon cycle are insufficient to adequately constrain the historical carbon budget, and consequently the strength of terrestrial CO2 fertilization effect as it is represented in the model, given the large uncertainty associated with LUC emissions over the historical period.