title: Negative emissions physically needed to keep global warming below 2 °C.
abstract: To limit global warming to <2 °C we must reduce the net amount of CO2 we release into the atmosphere, either by producing less CO2 (conventional mitigation) or by capturing more CO2 (negative emissions). Here, using state-of-the-art carbon-climate models, we quantify the trade-off between these two options in RCP2.6: an Intergovernmental Panel on Climate Change scenario likely to limit global warming below 2 °C. In our best-case illustrative assumption of conventional mitigation, negative emissions of 0.5-3 Gt C (gigatonnes of carbon) per year and storage capacity of 50-250 Gt C are required. In our worst case, those requirements are 7-11 Gt C per year and 1,000-1,600 Gt C, respectively. Because these figures have not been shown to be feasible, we conclude that development of negative emission technologies should be accelerated, but also that conventional mitigation must remain a substantial part of any climate policy aiming at the 2-°C target.
authors.affiliation: Laboratoire des Sciences du Climat et de l'Environnement (LSCE), Institut Pierre-Simon Laplace (IPSL), CEA - CNRS - UVSQ, CEA l'Orme des Merisiers, 91191 Gif-sur-Yvette, France.|Centre International de Recherche sur l'Environnement et le Développement (CIRED), CNRS - Ecole des Ponts ParisTech - EHESS - AgroParisTech - CIRAD, Campus du Jardin Tropical, 45 bis avenue de la Belle Gabrielle, 94736 Nogent-sur-Marne, France.
authors.forename: T
authors.initials: T
authors.lastname: Gasser
authors.affiliation: Centre International de Recherche sur l'Environnement et le Développement (CIRED), CNRS - Ecole des Ponts ParisTech - EHESS - AgroParisTech - CIRAD, Campus du Jardin Tropical, 45 bis avenue de la Belle Gabrielle, 94736 Nogent-sur-Marne, France.
authors.forename: C
authors.identifier: http://orcid.org/0000-0002-9405-256X
authors.initials: C
authors.lastname: Guivarch
authors.affiliation: Japan Agency for Marine-Earth Science and Technology, 3173-25 Showa-machi, Kanazawa-ku, Yokohama, Kanagawa 236-0001, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Tachiiri
authors.affiliation: Met Office, Hadley Centre, FitzRoy Road, Exeter EX1 3PB, UK.
authors.forename: C D
authors.initials: CD
authors.lastname: Jones
authors.affiliation: Laboratoire des Sciences du Climat et de l'Environnement (LSCE), Institut Pierre-Simon Laplace (IPSL), CEA - CNRS - UVSQ, CEA l'Orme des Merisiers, 91191 Gif-sur-Yvette, France.
authors.forename: P
authors.initials: P
authors.lastname: Ciais