By Dr. Kirsten Isensee, Dr. Katherina School, Professor Steve Widdicombe and Jeremy Sterling*
PARIS | 11 November 2024 (IDN) — Governments meeting in Baku for the COP29 Climate Summit have many mountains to climb in their quest to raise ambitions and accelerate action. They must not, however, forget about the ocean. Because the blue part of our planet plays a dual role in climate change, as both the scene of escalating climate impacts, and the source of promising climate solutions.
To get on track to meeting their 1.5oC targets, delegates at COP29 need to make sure the ocean is fully accounted for and prioritized across climate change research and forecasting, and addressed across Parties’ engagement with the UNFCCC process, e.g. in National Adaptation Plans, Biennial Reports, National Communications, and Nationally Determined Contributions (NDCs).
The ocean is our planet’s greatest climate ally. It absorbs one-quarter of humanity’s CO2 emissions and 90% of the excess heat this generates, however this comes at a high cost. Marine ecosystems are paying the price in the form of three interconnected climate stressors: warming, acidification, and deoxygenation.
And the impacts—along with others, such as sea level rise—are already affecting the growing blue economy, putting the livelihoods and food security of millions of people at risk, and helping to drive extreme weather and ocean events.
One climate hotspot—the Mediterranean region—is warming 20% faster than the global average. The past two summers have seen record-breaking temperatures in the Mediterranean Sea, wreaking havoc on marine biodiversity and accelerating the region’s hydrological cycle, with tragic consequences.
Last month’s catastrophic flooding in Spain’s Valencia region was a painful reminder of what can happen when exceptionally high ocean temperatures lead to a warmer atmosphere able to hold more moisture. A year’s worth of rain fell in just 8 hours, fuelling flash floods and devastation.
On track to be the warmest year on record
COP29 comes at the end of what is firmly on track to be the warmest year on record. As the last major global gathering before the February 2025 deadline for States to submit their new NDCs, it is crucial that COP29 boosts momentum for far more ambitious national commitments to cut CO2 emissions.
This is the only real solution to the unprecedented rates of ocean warming, acidification and deoxygenation documented in IOC-UNESCO’s 2024 State of the Ocean Report.
Ocean warming is accelerating from the surface down to the abyss. The rate of warming in the top 2,000 metres of the ocean has doubled in the past two decades. As well as impacting storm patterns, this is driving rising sea levels, alterations in ocean currents, and dramatic changes in marine ecosystems.
Meanwhile, the continued absorption of large quantities of carbon is predicted to increase ocean acidification by more than 100% by the end of the century, threatening marine organisms, degrading habitats, and endangering fisheries and aquaculture. And to add insult in injury, as its acidity increases, the ocean’s capacity to absorb CO2 decreases, impeding its role in moderating climate change.
To complete this triad of climate stressors, the ocean’s oxygen content is diminishing, caused by a complex combination of climate change impacts and feedback. Worsening hypoxia and expanding low oxygen areas are a problem for aerobic ocean life, which needs dissolved oxygen to survive.
State of the Ocean Report
While the latest data and trends indicate a relatively rapid ocean response to recent climate change, one of the most important messages of the State of the Ocean Report is that we urgently need more and better distributed observation systems to discern and map ocean warming, acidification and deoxygenation. Integrating these observations with forecasting models will improve our understanding of the patterns, drivers and biological impacts of these changes both now and in the future.
As the State of the Ocean Report makes clear, we cannot address climate change without putting the ocean front and centre. That means States should include ocean-based solutions in the climate adaptation and mitigation plans presented in their new NDCs. It also means that the next edition of the Intergovernmental Panel on Climate Change (IPCC) assessment report (AR7) needs to improve the data and information related to ocean warming, acidification and deoxygenation, and account for these stressors correctly in their climate scenarios.
There is a major potential in AR7 to address ocean-climate issues as an interdisciplinary topic in integrated, cross-working group assessments.
We also urge the governments and other key stakeholders gathered in Baku to allocate the necessary resources to expand and enhance the observation systems for monitoring acidification, warming and deoxygenation across the ocean.
This will enhance our understanding of ocean-climate impacts and allow governments to develop effective strategies for mitigation and adaptation at relevant scales. It will also allow more accurate forecasting of extreme events like the one just experienced in Valencia.
While the delegates at COP29 jostle over climate finance, they must remember to invest in ocean research and resilience as key components of both global action to combat climate change and local mitigation strategies.
*Dr. Kirsten Isensee is Programme Specialist Ocean Carbon and Sinks at the Intergovernmental Oceanographic Commission of UNESCO; Dr. Katherina School is Associate Project Officer – Ocean Acidification – Ocean Science Section Intergovernmental Oceanographic Commission of UNESCO; Jeremy Sterling is Consultant Ocean Science – Intergovernmental Oceanographic Commission of UNESCO; Professor Steve Widdicombe is Director of Science and Deputy Chief Executive, Plymouth Marine Laboratory, UK. [IDN-InDepthNews]
Image: Sea turtle at surface. Credit: Gregory Piper | Ocean Image Bank
