“The Role of Oceans in Climate Regulation and Achieving Sustainable Development Goals: A Scientific Analysis of Challenges and Solutions”
If you look at planet Earth from an airplane window, you would call it a water planet rather than an earth planet, due to the vast expanse of water bodies covering approximately 71% of the Earth’s surface area, spanning about 361 million square kilometers. Land accounts for approximately 29%, covering about 149 million square kilometers. Ocean and sea waters represent the vast majority of Earth’s water, constituting alone approximately 96.5% to 97% of the Earth’s total hydrosphere.
On World Oceans Day, observed annually on June 8, we collectively affirm the importance of reimagining our relationship with the oceans as a fundamental pillar of life on planet Earth and a natural resource that demands greater responsibility and protection.
World Oceans Day is commemorated with the aim of highlighting the importance of oceans. This year’s celebrations focused on the theme “Reimagine” and the subject “Our Ocean, Our Future: Learning to Conserve Our Ocean.” All of this is crucial for preserving biodiversity in these oceans and their role in sustaining ecological systems on the Earth’s surface.
“The ocean is suffering a serious crisis – and we are demanding more than it can give. We cannot continue to treat the ocean as if it has limitless capacity. We must establish a new relationship with it, built on the basis of science and within the framework of international law.”
With these concise and impactful words, United Nations Secretary-General António Guterres, in his message on the occasion of World Oceans Day on June 8, 2025, called upon the international community to radically reassess its relationship with the oceans. This call comes at a critically sensitive time, as the oceans face a “global state of emergency” that threatens their ability to continue performing the vital functions upon which life on planet Earth depends.
The Ocean as a Regulator of Earth’s Climate: Facts and Figures
The ocean plays a pivotal role in regulating Earth’s climate, manifested in its exceptional capacity to absorb heat and carbon dioxide. Data released by the 2025 Ocean Conference indicates that the ocean has absorbed 30% of carbon dioxide emissions resulting from human activities since the industrial era. While this absorption protects us from the full impact of global warming, it comes at a significant cost: ocean acidification.
Since the industrial era, the pH of ocean waters has decreased by approximately 30%. This chemical shift is not merely a figure in a scientific equation; it represents a transformation that threatens marine organisms dependent on calcium carbonate to build their shells and skeletons, such as corals, mollusks, and plankton. Scientific models indicate that the ocean could become 150% more acidic by 2100 if emissions continue to grow.
The ocean is also recording unprecedented increases in temperature. The year 2024 recorded the highest ocean temperatures ever observed, with accelerating warming rates across all depths. This warming is responsible for approximately 40% of global sea-level rise. Sea level has risen by 9 centimeters over the past thirty years, with the rate of rise doubling during this period due to melting ice sheets in Greenland and West Antarctica.
The Ocean and Biodiversity: A Treasure Under Threat
The ocean is one of the largest reservoirs of biodiversity on Earth, containing an estimated between 500,000 and 10 million marine species, many of which remain undiscovered. The oceans encompass 32 of the 34 known phyla in the animal kingdom, with over 2,000 new species identified annually.
However, this unique biodiversity faces existential threats. According to the International Union for Conservation of Nature (IUCN), 46,300 species are threatened with extinction globally, representing 28% of all assessed species. Approximately 50% of live coral cover has been lost since the 1870s, and 44% of reef-building coral species are at risk of extinction. The World Meteorological Organization (WMO) has announced that over 90% of the ocean experienced heatwave conditions in 2023, leading to the fourth recorded global coral bleaching event.
Recent studies indicate that exposure to climate-related risks could double between 1.5°C and 2°C of warming, and double again between 2°C and 3°C. This places marine ecosystems under increasing pressure that may exceed their adaptive capacity.
The Ocean and Sustainable Development Goals: An Inseparable Interconnection
Sustainable Development Goal 14 (Life Below Water) constitutes a central focus of international efforts to protect the oceans. Nevertheless, this goal remains among the least funded of the seventeen Sustainable Development Goals. The third United Nations Ocean Conference was held in Nice, France, from June 9 to 13, 2025, with the participation of member states, civil society organizations, and the private sector, aiming to “accelerate action and mobilize all stakeholders to conserve and sustainably use the oceans.”
Statistics related to SDG 14 reveal significant challenges:
· Only 7% of fish stocks are fished within biologically sustainable levels (declining from 10% in 1974)
· 18,200 marine protected areas cover 8.12% of the oceans, still below the 10% target set by the 2030 Sustainable Development Agenda and the 30% ambition established by the Kunming-Montreal Global Biodiversity Framework
· Approximately 17 million tons of plastic enter the ocean annually, with projections of doubling or tripling by 2040 unless radical measures are implemented
An estimated 492 million people depend at least partially on small-scale fisheries, nearly half of whom are women. This illustrates the human and social dimension of the ocean crisis, as the degradation of marine ecosystems directly threatens the livelihoods of millions and global food security.
A New Legal Framework for the Oceans: From Nice to the Future
The 2025 Nice Conference marked a significant turning point in the trajectory of international ocean governance, with the adoption of the declaration “Our Ocean, Our Future: United for Urgent Action.” The declaration affirmed the necessity of strengthening coordinated global actions to address the interconnected threats facing the oceans, including climate change, biodiversity loss, and pollution.
Key commitments emerging from the conference included:
1. Integration of international frameworks: The declaration called for enhanced coordinated action between the United Nations Framework Convention on Climate Change (UNFCCC), the Convention on Biological Diversity (CBD), and the Agreement on Biodiversity Beyond National Jurisdiction (BBNJ)
2. 30×30 Target: Commitment to protect and manage at least 30% of marine and coastal areas by 2030, in alignment with the Kunming-Montreal Global Biodiversity Framework
3. Addressing plastic pollution: Recognition of the necessity to develop a legally binding international instrument on plastic pollution, including in the marine environment, addressing the full life cycle of plastics
4. Support for Small Island Developing States: Recognition that Small Island Developing States (SIDS), least developed countries (LDCs), and coastal communities are disproportionately affected by sea-level rise, with a call to strengthen international cooperation to support their adaptive capacities
Cascading Impacts: Findings from Recent Scientific Research
Recent scientific research demonstrates that the impacts of climate change on the oceans are not merely future projections but present and accelerating realities. In the Eastern Mediterranean Sea, identified as a climate change hotspot, marine heatwaves are projected to occur more than seven times more frequently and last three times longer by the end of the 21st century.
Ocean acidification is exacerbated in this region due to its high alkalinity, which enables greater absorption of carbon dioxide. Studies indicate that the combined effects of ocean warming and acidification lead to alterations in the distribution of marine species, the migration of non-indigenous species, and the degradation of vital ecosystems.
In a pioneering study published in July 2025, researchers investigated the effects of ocean acidification and rising temperatures on bryozoan colonies in volcanic carbon dioxide seeps on the island of Ischia, Italy. The results demonstrated that ocean acidification leads to:
· Weakening of calcareous structures of living organisms, making them more fragile
· Disruption of the associated microbiome, depriving these organisms of essential biological functions
· Exacerbated loss of live cover and mortality when acidification is coupled with marine heatwaves
These findings are particularly concerning because bryozoans are habitat-forming organisms that play important roles in sediment production and shoreline protection.
Conclusion: A New Relationship with the Ocean
The message of the United Nations Secretary-General brings us back to the heart of the challenge: we cannot continue to treat the ocean as if it were a system with infinite capacity for endurance. The call for a “new relationship” with the ocean, built on the “basis of science” and within the “framework of international law”, is an invitation to redefine humanity’s place within the planetary ecosystem.
Science today provides us with a precise understanding of the complex mechanisms linking the ocean to climate, biodiversity, the global economy, and food security. International law, represented by the United Nations Convention on the Law of the Sea, the BBNJ Agreement, and the Kunming-Montreal Framework, provides us with the necessary tools to translate this understanding into concrete actions.
Humanity’s choice is simple yet fateful: either we persist in the illusions of limitlessness, burdening the ocean beyond its capacity, and forever lose an invaluable biological, economic, and climatic treasure; or we summon the political and scientific courage to build this new relationship, wherein the ocean becomes a partner in sustainable development, not a repository for our waste and a victim of our unlimited ambitions. As the Secretary-General stated: “We must invest significantly in science, conservation, and the sustainable blue economy.” The ocean needs our help today, before it is too late.
References:
1. United Nations. (2025). Ocean Action Panel 7: Leveraging Ocean, Climate and Biodiversity Interlinkages. Concept paper for the 2025 UN Ocean Conference, Nice, France. A/CONF.230/2025/10.
2. United Nations Secretary-General. (2025, June 8). World Oceans Day Message. United Nations.
3. Figuerola, B., et al. (2025). Interactive effects of ocean acidification and warming disrupt calcification and microbiome composition in bryozoans. Communications Biology, 8, 1135. doi: 10.1038/s42003-025-08524-8.
4. United Nations Sustainable Development. (2025). Goal of the Month – Goal 14: Life below water. United Nations.
5. United Nations. (2025). Report of the 2025 United Nations Conference to Support the Implementation of Sustainable Development Goal 14. Nice, France, 9–13 June 2025. A/CONF.230/2025/16.
6. Christou, E. D., et al. (2025). Climate change in the “vulnerable” Eastern Mediterranean and adjacent areas: a literature review of ecological impacts and threats. Marine Environmental Research, 211, 107390. doi: 10.1016/j.marenvres.2025.107390.
7. United Nations. (2025). Ocean Action Panel 1: Conserving, sustainably managing and restoring marine and coastal ecosystems including deep-sea ecosystems. Concept paper for the 2025 UN Ocean Conference, Nice, France.
8. Schmidtko, S., Stramma, L., & Visbeck, M. (2017). Decline in global oceanic oxygen content during the past five decades. Nature, 542, 335–339.
9. Cheng, L., et al. (2025). Record high ocean temperatures in 2024.
10. IOC-UNESCO. (2024). State of the Ocean Report 2024.
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