森林と海洋は排出削減の対象外、研究が警告(Forests and oceans shouldn’t count toward emission reductions, study warns)

2024-11-18 インペリアル・カレッジ・ロンドン(ICL)

The world will keep heating after net zero is achieved if countries include natural carbon sinks in their emission targets, a new study warns.

＜関連情報＞

• https://www.imperial.ac.uk/news/258333/forests-oceans-shouldnt-count-toward-emission/
• https://www.nature.com/articles/s41586-024-08326-8

地質学的ネット・ゼロと炭素吸収源の分解会計の必要性 Geological Net Zero and the need for disaggregated accounting for carbon sinks

Myles R. Allen,David J. Frame,Pierre Friedlingstein,Nathan P. Gillett,Giacomo Grassi,Jonathan M. Gregory,William Hare,Jo House,Chris Huntingford,Stuart Jenkins,Chris D. Jones,Reto Knutti,Jason A. Lowe,H. Damon Matthews,Malte Meinshausen,Nicolai Meinshausen,Glen P. Peters,Gian-Kasper Plattner,Sarah Raper,Joeri Rogelj,Peter A. Stott,Susan Solomon,Thomas F. Stocker,Andrew J. Weaver & Kirsten Zickfeld
Nature Published:18 November 2024
DOI:https://doi.org/10.1038/s41586-024-08326-8

We are providing an unedited version of this manuscript to give early access to its findings. Before final publication, the manuscript will undergo further editing. Please note there may be errors present which affect the content, and all legal disclaimers apply.

Abstract

Achieving net zero global emissions of carbon dioxide (CO₂), with declining emissions of other greenhouse gases, is widely expected to halt global warming. CO₂ emissions will continue to drive warming until fully balanced by active anthropogenic CO₂ removals. For practical reasons, however, many greenhouse gas accounting systems allow some “passive” CO₂ uptake, such as enhanced vegetation growth due to CO₂ fertilisation, to be included as removals in the definition of net anthropogenic emissions. By including passive CO₂ uptake, nominal net zero emissions would not halt global warming, undermining the Paris Agreement. Here we discuss measures addressing this problem, to ensure residual fossil fuel use does not cause further global warming: land management categories should be disaggregated in emissions reporting and targets to better separate the role of passive CO₂ uptake; where possible, claimed removals should be additional to passive uptake; and targets should acknowledge the need for Geological Net Zero, meaning one tonne of CO₂ permanently restored to the solid Earth for every tonne still generated from fossil sources. We also argue that scientific understanding of net zero provides a basis for allocating responsibility for the protection of passive carbon sinks during and after the transition to Geological Net Zero.