Ce que les entreprises et les villes doivent faire pour rester dans des limites environnementales "sûres et justes" pour le carbone, l'eau, les nutriments, la terre et d'autres ressources naturelles fait l'objet d'une nouvelle série de recommandations d'experts de la Commission de la Terre.

Les auteurs, issus d'institutions universitaires telles que l'école de commerce de l'Université d'Exeter, ont publié dans la revue Nature les principales lacunes en matière de connaissances pour les chercheurs afin d'aider les villes et les entreprises à fonctionner dans les limites du système terrestre. .

Il précède un rapport de la Commission de la Terre qui doit paraître l'année prochaine et qui décrira une gamme de "limites du système terrestre" (ESB) basées sur les dernières évaluations scientifiques, de modélisation et de littérature.

Il y a dix ans, les scientifiques ont défini un ensemble de limites planétaires à l'intérieur desquelles l'humanité peut opérer « en toute sécurité » dans neuf domaines :le changement climatique, la biosphère, les nutriments, l'eau, l'utilisation des terres, l'acidification des océans, l'appauvrissement de la couche d'ozone, les aérosols et les nouvelles entités. -les ESB à définir ajouteront une dimension de justice sociale, pour garantir que les limites quantifiées sont "justes" ainsi que "sûres".

Les chercheurs soutiennent que des méthodes doivent être développées pour identifier ce que les villes et les entreprises doivent faire pour que le monde reste dans les ESB et pour les aider à évaluer leur part de responsabilité vis-à-vis des budgets mondiaux de carbone, d'eau, de nutriments, de terres et d'autres ressources naturelles, et fixez-vous des objectifs pour les protéger.

Les auteurs plaident pour des "objectifs basés sur la science" et affirment que les objectifs doivent être "mesurables, réalisables et limités dans le temps", soulignant que peu de villes et d'entreprises ont actuellement des objectifs basés sur la science et que parmi les 200 villes les plus émettrices, seules 110 ont des engagements "net zéro" qui s'alignent sur l'Accord de Paris.

L'auteur principal Xuemei Bai, professeur émérite à la Fenner School of Environment and Society de l'Université nationale australienne et membre de la Commission de la Terre, déclare que "c'est un long parcours, mais l'humanité doit rester dans les limites des budgets limités de notre planète". et des méthodes socialement justes pour allouer les ressources naturelles et les responsabilités sont essentielles pour les respecter."

"Les villes et les entreprises sont les principaux contributeurs aux changements planétaires, mais aussi des acteurs clés pour les solutions. Il existe des lacunes dans les connaissances sur la manière de traduire ces frontières en allocations concrètes pour les entreprises et les villes, et nos recommandations visent à combler ces lacunes."

La co-auteure Gail Whiteman, professeure de développement durable à l'école de commerce de l'Université d'Exeter, déclare que leur "travail plaide en faveur d'actions conjointes révolutionnaires des entreprises et des villes pour s'attaquer de manière synergique aux points chauds urbains dans les limites du système terrestre en utilisant des limites fondées sur la science. , corporate and urban targets are siloed. A key next step is for initiatives like the International Sustainability Standards Board and the Science Based Targets Network to integrate ESBs and encourage joint action."

Co-author Johan Rockström, co-chair of the Earth Commission and director of the Potsdam Institute for Climate Impact Research, says that "Earth system boundaries are linked, so targets need to be aligned. Measures that focus on one domain can be beneficial or detrimental to others."

"Climate change, for instance, depends on land-based processes—such as methane emissions from thawing permafrost and weakened carbon sinks through deforestation. Several pressure points can combine so that tipping points are reached sooner."

Co-author Şiir Kılkış, senior researcher at the Scientific and Technological Research Council of Turkey says that "cities exchange people, energy and goods with their local and global hinterlands. The top 200 cities with the largest greenhouse-gas emissions also host the headquarters of 360 of the top 500 emitting companies."

"Looking across domains, more than 50% of these cities and companies are in water-stressed areas, including Mexico City, Santiago, Beijing, Madrid, New Delhi, Rome, Istanbul in Turkey and Phoenix, Arizona."

Co-author Anders Bjørn, postdoctoral fellow at the Technical University of Denmark says that "it is encouraging that more and more companies are setting reduction targets for carbon emissions based on the 1.5-degree Paris goal. These science-based targets are typically more ambitious than national commitments and should inspire more action from policymakers at different levels. Now we need the biggest emitters and resource consumers to step up and do their part in limiting climate change and protecting all other Earth system boundaries."

Erin Billman, Executive Director of Science Based Targets Network advised that "Earth Commission's critical work on Earth system boundaries is directly informing Science Based Targets Network's development of environmental science-based targets (SBTs) for companies and cities, which build upon climate SBTs to cover freshwater, land, ocean and biodiversity."

The authors highlight seven recommendations for researchers aiming to translate ESBs into concrete steps for cities and businesses.

1. Develop common procedures

Principles and protocols must be developed, and methods, metrics, assumptions and uncertainties must be clear. Without such clarity, cities and companies may seek to minimize their own responsibility and maximize the resources they claim; powerful actors may exert undue influence.

2. Focus on interactions

Earth system boundaries are linked, so targets need to be aligned. Climate change, for instance, depends on land processes—from methane emissions from thawing permafrost to weakened carbon sinks through deforestation. Researchers should identify key activities that span several ESBs and evaluate what can be achieved by targeting them.

3. Acknowledge dynamics

Most targets focus on a particular date, like 2030 or 2050. But pathways are important. For example, reducing carbon emissions linearly to net zero by 2050 would result in less warming than keeping them high for the next decade and then dropping suddenly. Researchers must develop an agile approach—time-sensitive and dynamic goal setting that allows regular checking, adjustment and updating.

4. Allocate for justice and equity

Targets need to reflect socioeconomic contexts, such as income and consumption levels, environmental impacts or capabilities to act. For example, cities with high consumption levels, historical emissions or high revenues should arguably adopt more stringent targets than others.

5. Support monitoring and accountability

Much work needs to be done to support monitoring and accountability. We recommend that initiatives, such as the new International Sustainability Standards Board, engage with cross-disciplinary scientists to ensure that their proposed "global baseline of sustainability-related disclosure standards" explicitly link cities and companies with ESBs. Independent auditing systems are also needed.

6. Establish governance mechanisms

New policies and regulations will be needed to incentivize or mandate cities and companies to adopt targets. One approach is to recognize each of the ESB domains as a global commons. For climate change, the United Nations could initiate intergovernmental panels and call on governments to mandate science-based target setting for large cities and companies. There is no guarantee this would fix the problem, but it would put ESBs onto the policy agenda.

7. Design incentives

Widespread adoption of science-based target setting by cities and companies is essential, as they can also prompt and incentivize national governments to follow the suit. Quality trademarks for products and services, such as "kitemarks" or positive labels, could be issued to raise awareness and encourage others. Financial incentives should be scaled up and expanded. + Explorer plus loin

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