21世紀における人類による海洋酸性化とそのカルシ化する生物への影響

James C Orr¹, Victoria J Fabry, Olivier Aumont

¹Laboratoire des Sciences du Climat et de l'Environnement, UMR CEA-CNRS, CEA Saclay, F-91191 Gif-sur-Yvette, France. orr@cea.fr

Nature

|September 30, 2005

まとめ

二酸化炭素の上昇による海洋酸化は,海洋生物を脅かしています. 予測によると,2050年までに南洋の過飽和が危機的になり,鳥類やサンゴなどの貝殻形成生物に影響を及ぼすことになる.

科学分野:

海洋化学と海洋学
気候変動が海洋生態系に及ぼす影響
バイオジオケミカルサイクルとは

背景:

地表の海洋は現在,炭酸カルシウムで飽和しています.
大気中の二酸化炭素の増加は,海洋のpHと炭酸イオン濃度を下げます.
この傾向は,サンゴやプランクトンを含む海洋の化生物が骨格を維持するのを妨げています.

研究の目的:

将来の海洋カルシウム炭酸の飽和度レベルを予測するために.
人為的な二酸化炭素排出量の影響を,通常通り事業を続けるシナリオで評価する.
海洋生態系における有害な条件のタイムラインを評価する.

主な方法:

13の海洋-炭素サイクルモデルを利用した.
IS92aの排出シナリオでシミュレートされたカルシウム炭酸の飽和度.
船上で実験を行い,活体鳥類を予測された飽和不足レベルに晒した.

主要な成果:

南洋の地表水は,2050年までにアラゴニットに関して不飽和になると予測されています.
低飽和は2100年までに南洋全体と亜北極太平洋に広がる可能性がある.
プテロポッドの殻は,予測された過飽和に曝されたときに,著しい溶解を示した.

結論:

高緯度海洋生態系にとって有害な条件は,数十年以内に発生する可能性があります.
以前の推定では,これらの変化は何世紀にもわたって起こると示唆されていました.
生態系の被害を軽減するために,二酸化炭素排出量に対する緊急の行動が示唆されています.

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