The Legal Power of Highest Possible Ambition: Setting Legal and Scientific Indicators to Assess Highest Possible Ambition under Article 4(3) of the Paris Agreement

20892 7 111222 2 336440 document 111222 clla-article-p7_002.pdf application/pdf f98bc96a31fa2244211c42ec6a6fb3b3 MD5 674457 2025-09-24 08:57:34 https://pure.iiasa.ac.at/id/eprint/20892/1/clla-article-p7_002.pdf 20892 1 1 application/pdf text en public cc_by_4

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published 111228 2 336451 document 111228 lightbox.jpg image/png 58dfdf06d7776b30d25f31c6a1abf230 MD5 30930 2025-09-24 09:07:37 https://pure.iiasa.ac.at/id/eprint/20892/2/lightbox.jpg 20892 2 2 image/png other Thumbnails conversion from text to thumbnail_lightbox en public

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http://eprints.org/relation/isVersionOf https://pure.iiasa.ac.at/id/document/111222 http://eprints.org/relation/isVolatileVersionOf https://pure.iiasa.ac.at/id/document/111222 http://eprints.org/relation/isIndexCodesVersionOf https://pure.iiasa.ac.at/id/document/111222 archive 353 disk0/00/02/08/92 2025-09-24 08:59:03 2026-01-08 08:25:11 2025-09-24 08:59:03 article show Voigt C. Sauter P. Teixeira R.G Rogelj J. 8630 0000-0003-2056-9061 Schleussner C.-F. 9915 0000-0001-8471-848X Sulyok Katalin The Legal Power of Highest Possible Ambition: Setting Legal and Scientific Indicators to Assess Highest Possible Ambition under Article 4(3) of the Paris Agreement pub ECE IACC ICI TISS Paris Agreement; highest possible ambition; law and science; climate change; mitigation; due diligence The Paris Agreement requires each state party to submit a nationally determined contribution ( ndc ) every five years. Current ndc s fall short of limiting global warming to 1.5°C, making the 2025 submissions crucial. Against commonly held belief, the level of climate change mitigation ambition in ndc s does not entirely lie within the discretion of Parties. Article 4(3) of the Paris Agreement requires that each party’s successive ndc will reflect its ‘highest possible ambition’ ( hpa ); an important normative requirement crucial for raising mitigation ambition. This article examines hpa and provides legal and scientific indicators for assessing whether parties’ 2025 ndc s and subsequent submissions align with the hpa requirement in Article 4(3). In doing so, a comprehensive framework essential for ensuring that ndc s are ambitious, credible, and effective in reducing emissions and mitigating climate impacts is offered. The success of the global effort against climate change depends on parties reflecting their hpa in ndc s and implementing effective mitigation measures, highlighting the urgency of hpa in each party’s climate efforts. 2025-09-08 published Brill doi:10.1163/18786561-bja10063 254 3686 public Climate Law 15 7-30 24 TRUE 1878-6553 info:eu-repo/semantics/article