大気中のCO2の垂直プロファイルから弱い北方と強い熱帯の土地の炭素吸収
Britton B Stephens1, Kevin R Gurney, Pieter P Tans
1National Center for Atmospheric Research, Boulder, CO 80305, USA. stephens@ucar.edu
まとめ
大気中の二酸化炭素 (CO2) の測定はモデルに異議を唱え,北部の炭素吸収が弱く,熱帯の炭素吸収が潜在的に強いことを示唆しています. これは,以前考えられていたよりも,北部の陸地層が産業用CO2排出量を吸収する役割が小さいことを示している.
科学分野:
- 大気化学と炭素循環科学.
背景:
- 大気モデルでは,伝統的に,熱帯から北緯度への重要な陸上の炭素移転を推定しています.
- 以前の推定では,北部の炭素の吸収と熱帯の炭素の排出がかなり高いことが示唆されていた.
研究 の 目的:
- 大気モデルによるCO2転送の推定値と観測された垂直大気CO2分布を比較することによって,大気モデルの正確性を調査する.
- 世界的な炭素循環における熱帯と北部の生態系の役割を再評価する.
主な方法:
- 昼間の垂直大気中の二酸化炭素 (CO2) の分布の分析.
- 観測されたCO2のグラデーションを複数の大気モデルからの出力と比較.
- 熱帯地域と北部の地域のための炭素フロースの推定値の精製.
主要な成果:
- 観測された年間平均の垂直CO2グラデーションは,熱帯から北への大規模な炭素移転を予測するモデルと矛盾しています.
- 観測されたグラデントを最もよく再現するモデルは,北部の炭素吸収が弱く (-1,5 Pg C year ((-1)) と熱帯の排出が弱く (+0.1 Pg C year ((-1)) と推定しています.
- これらの改訂された推定値は,以前のコンセンサスの数字 (-2.4 Pg C年 ((-1) 摂取量, +1.8 Pg C年 ((-1) 排出量) と著しく異なる.
結論:
- 産業用CO2排出量の北部の陸上吸収は,以前に推定されたより少ない役割を果たしているようです.
- 土地利用による排出量を考慮すると,熱帯の生態系は,重要な炭素吸収源として機能する可能性があります.
- 大気中のCO2輸送モデルの見直しは,世界の炭素動態を正確に理解するために極めて重要です.
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