The Biodiversity Crisis

ORIGINALLY WRITTEN JUNE 2025.

The climate crisis is often talked about. It is sometimes forgotten that we are facing another crisis: an unprecedented decline in biodiversity. These two crises are inextricably linked. Whilst overexploitation of biological resources has had the largest relative impact on marine biodiversity, climate change is also a direct driver of biodiversity loss. Here, we take a quick look at marine biodiversity, its decline, and efforts to address this.

Biodiversity can be defined as the variety and variability of living organisms, including diversity within species, between species and of ecosystems [1]. As the ocean represents approximately 99% of the Earth’s biologically habitable space, marine biodiversity is of extreme importance [2]. The Convention on Biological Diversity (CBD) (adopted in 1992) and the Kunming-Montreal Global Biodiversity Framework (adopted in 2022) both acknowledge that biodiversity is fundamental to human well-being, a healthy planet, and humanity’s economic and social development [1], [3].

Yet biodiversity is declining at unprecedented rates, and this trend is set to continue. The collapse in biodiversity is described as a loss of the number of species, as species extinction has accelerated over the last century, and around one million species face extinction, as well as a reduction in species abundance (number of individuals per species) [4], [5]. Even without extinction, species abundance may decline too much for that species to perform its ecological function. As such, the world is experiencing species homogenisation and ecosystem reorganisation with consequences on ecosystem functioning, and subsequently ecosystem services [4]. In fact, biodiversity loss was predicted to be one of the biggest threats facing humanity between 2020 and 2030 [6].

Combating biodiversity loss and reversing it to some degree requires mainstreaming biodiversity into relevant policies, strategies, and practices across sectors and at different policy levels [7]. International efforts have long been underway to address the issue of biodiversity loss:

1992 — The Convention on Biological Diversity (CBD) is a global agreement that aims to conserve biological diversity, ensure its sustainable use, and promote fair and equitable sharing of the benefits arising from genetic resources [1].
2011 — The Aichi Biodiversity Targets were strategic, global goals to halt biodiversity loss under the CBD as part of the Strategic Plan 2011–2020 [8].
2015 — The 2030 Agenda for Sustainable Development recognises the global threat to biodiversity and outlines that development should respect biodiversity to ensure long-term and sustainable benefits from natural resources [9].
2019 — The European Green Deal (EGD) is a growth strategy that aims for no net emissions of greenhouse gases in the EU by 2050 whilst preserving and restoring biodiversity [10].
2020 — The EU Biodiversity Strategy for 2030 sets out the ambition to scale up the restoration of ecosystems, ensuring resilience and adequate protection. Among other actions, the EC commit to protecting a minimum of 30% of the EU’s sea area (30×30 target) [6].
2021–2030 — The UN Decade on Ecosystem Restoration [11].
2022 — The Kunming-Montreal Global Biodiversity Framework sets out an ambitious goal to transform our societies’ relationship with biodiversity by 2030, in line with the 2030 Agenda for Sustainable Development. With the development of 23 action-oriented global targets, the Framework aims to catalyse urgent action by Governments to halt and reverse biodiversity loss over the decade to 2030 [3].
2024 — The EU Nature Restoration Regulation (NRR) outlines rules for Member States to contribute to long-term and sustained recovery of biodiverse and resilient ecosystems. Objectives include the effective and area-based restoration measures to cover at least 20% of sea areas by 2030, with specific objectives outlined in Article 5: Restoration of marine ecosystems [12].

The biodiversity crisis is driven by human-induced changes. In the marine environment, direct overexploitation of biological resources has had the largest relative impact on biodiversity, but climate change is also a direct driver of biodiversity loss [5]. As such, the biodiversity and climate change crises are inextricably linked [4] and ensuring effective preservation of marine ecosystems is even more important in this context [13].

References

[1] CBD, Secretariat, ‘Convention on Biological Diversity’. United Nations, 1992. Accessed: Feb. 11, 2025. [Online]. Available: https://www.cbd.int/doc/legal/cbd-en.pdf

[2] IPCC, The Ocean and Cryosphere in a Changing Climate: Special Report of the Intergovernmental Panel on Climate Change, 1st ed. Cambridge University Press, 2022. doi: 10.1017/9781009157964.

[3] Convention on Biological Diversity, ‘Kunming-Montreal Global Biodiversity Framework’, CBD/COP/DEC/15/4, 2022. [Online]. Available: https://www.cbd.int/doc/decisions/cop-15/cop-15-dec-04-en.pdf

[4] P. Jarne, ‘The Anthropocene and the biodiversity crisis: an eco-evolutionary perspective’, C. R. Biol., vol. 348, no. G1, pp. 1–20, Jan. 2025, doi: 10.5802/crbiol.172.

[5] E. Brondizio, S. Diaz, J. Settele, and H. Ngo, Global assessment report on biodiversity and ecosystem services of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. Bonn: Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), 2019. [Online]. Available: https://zenodo.org/records/6417333

[6] EC, ‘EU Biodiversity Strategy for 2030: Bringing nature back into our lives’, COM(2020) 380 final, 2020. Accessed: Feb. 11, 2025. [Online]. Available: https://eur-lex.europa.eu/legal-content/EN/ALL/?uri=celex:52020DC0380

[7] P. Haapasaari et al., ‘Deliverable 6.1 State of the art on key barriers and levers for policy coherence’, Project deliverable, Jan. 2024. [Online]. Available: https://msp4bio.eu/wp-content/uploads/2024/07/Deliverable-6.1_State-of-the-art-on-key-barriers-and-levers-for-policy-coherence-1.pdf

[8] CBD, ‘Strategic Plan for Biodiversity 2011–2020 and the Aichi Targets’, Secretariat of the Convention on Biological Diversity, 2010. [Online]. Available: https://www.cbd.int/doc/strategic-plan/2011-2020/aichi-targets-en.pdf

[9] UNGA, ‘Transforming our world: the 2030 Agenda for Sustainable Development’, Resolutions / Recommendations / Declarations / Decisions A/RES/70/1, 2015. [Online]. Available: https://docs.un.org/en/A/RES/70/1

[10] EC, Secretariat-General, ‘Communication from the Commission to the European Parliament, the European Council, the Council, the European Economic and Social Committee and the Committee of the Regions: The European Green Deal’, Communication COM/2019/640 final, 2019. [Online]. Available: https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=COM:2019:640:FIN

[11] IOC-UNESCO and EC, ‘Updated Joint Roadmap to accelerate Marine/Maritime Spatial Planning processes worldwide MSProadmap (2022–2027)’, France, Programme and meeting document IOC/2022/TS/182, 2022. [Online]. Available: https://unesdoc.unesco.org/ark:/48223/pf0000385718

[12] EP and Council of the EU, ‘Regulation (EU) 2024/1991 of the European Parliament and of the Council of 24 June 2024 on nature restoration’, Official Journal of the European Union, 2024/1991, 2024. [Online]. Available: https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A32024R1991&qid=1722240349976

[13] G. Rilov et al., ‘A fast‐moving target: achieving marine conservation goals under shifting climate and policies’, Ecological Applications, vol. 30, no. 1, p. e02009, Jan. 2020, doi: 10.1002/eap.2009.[2] R. Simmer, E. Jansen, K. Patterson, and J. Schnoor, ‘Climate Change and the Sea: A Major Disruption in Steady State and the Master Variables’, ACS Environ. Au, vol. 3, no. 4, pp. 195–208, Jul. 2023, doi: 10.1021/acsenvironau.2c00061.

References

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