[Un article de The Conversation écrit par Sabrina Speich – Professeure en océanographie et sciences du climat, École normale supérieure (ENS) – PSL]
Gradually, scientists from around the world have been able to put the ocean with an open heart. Today, scientists are unanimous: climate change is in progress, and it has dramatic consequences on the state of health of an ocean which has already absorbed 90 % of excess heat and 26 % of CO₂ emissions due to our human activities. For example, more acidic and warmer water threatens marine ecosystems such as corals, shells and the entire oceanic food chain.
Scientists also observe that three of the nine planetary limits are already crossed and that, among the ten main risks for the decade 2025-2035 to come, four of them are linked to the environment and the state of health of the ocean.
The ocean is the pillar of the climate machine
The climate system, supplied with energy by the sun, is mainly composed of tanks and flows between these tanks. The planet Earth thus has three large compartments that are the atmosphere, the continental surfaces and the oceans. The flows between these tanks are mainly flows of materials, energy and heat.
The oceans form one, connected to each other at the southern pole through the southern ring which encircles the Antarctic continent. This ocean is the unique fluid envelope on our planet, covering more than two -thirds of the surface of the globe and representing almost 96 % of the water available on earth. The ocean and the atmosphere are in permanent contact and air-mer exchanges are mainly on the basis of the water cycle, for example during precipitation or evaporation of seawater. These continuous exchanges allow the balance of the climate system by redistribution of flows and the installation of different climatic conditions in each region of the world.
In particular, heat and CO2 Atmospheric is absorbed by the ocean at the Air-Mer interface, then transported and redistributed on the globe thanks to sea currents and marine biological activity. This traffic is carried out in each of the ocean basins, from north to south and west to east. But it is also vertical, between the surface and the very great marine depths. Its average depth of 3,800 meters makes the ocean a huge heat tank with very strong thermal inertia, due to the physical properties of water.
By the capacity of its marine currents to absorb, to transport and to store in its greatest depths atmospheric signals and the many flows from other tanks, the ocean plays a key role in global climatic mechanisms and in planetary balance. It is one of the pillars of the climate system, so that scientists call it “thermostat of the planet”.
An open heart ocean thanks to the global ocean observation system, under the aegis of UNESCO
To understand the climate system, scientists are based on the combination of three types of ocean observations:
- the measures in situcollected at sea and which provide detailed data on the underwater layers to monitor the variability of the in-depth oceans and long-term changes;
- satellite observations, offering a spatial coverage extended by the first meters of the ocean surface to follow the elevation of sea level, ocean color, surface temperature and salinity or primary marine productivity;
- Digital models and assimilation of data which synthesize observations in order to describe the past, present and future evolution of the oceans.
Today, oceanic observations include a wide range of physical (temperature, salinity, etc.), biogeochemical (oxygen, dissolved carbon …) and biological (phytoplankton, zooplankton, etc.) parameters, essential to climate assessment, marine resources management and early alert systems. They are the only reliable source of information on the state of oceans and climate, and improve and validate digital models to refine their forecasts.
The Global Ocean Observing System (GOOS), an international program created in the early 1990s after the Second World Conference on the Geneva climate and the Earth Summit in Rio de Janeiro, coordinates the observation and surveillance of the ocean on a planet scale. Its objective is to better understand the state of the ocean, predict its evolution and support decisions in the face of climatic, environmental and societal issues.
It works as an integrated global network of ocean observations, combining data from satellites, buoys, profiling floats (such as the Argo program), ships and coastal stations.
The data collected by the Network of observations coordinated by Goos are free and open, accessible not only to researchers, but also to actresses and actors of civil society, to companies, to local authorities and to any organization involved in the management or protection of the ocean. This information is essential to monitor the health of marine ecosystems, anticipate extreme events, support climate policies and promote a sustainable blue economy.
Strengthen observation of oceans to shed light on climatic policies and management of marine ecosystems
A complete ocean observation system such as Goos meets multiple societal needs.
As we have seen, the ocean moderates global warming, therefore attenuating extreme weather phenomena. By improving the forecasting of marine heat waves, storm waves, proliferation of harmful algae and tsunamis, Goos contributes to the initiative “Early alerts for all”, launched in 2022 by the United Nations. Its objective is simple and ambitious: that each person on Earth is protected by an early alert system by 2027, a system which diffuses clear and accessible alerts to give time to prepare for the arrival of an extreme event.
While more than 90 % of world trade depends on maritime transport, fishing and aquaculture support billions of people, reinforced surveillance also supports a sustainable blue economy. In particular, ecosystem management, the planning of ocean uses and the sustainable exploitation of marine resources guarantee the resilience of ecosystems while promoting economic growth – mirror of the fourteenth objective of sustainable development (ODD 14) of the United Nations, “to keep and exploit in sustainable oceans, seas and marine resources for the purposes of sustainable development”.
The current Goos constitutes an essential infrastructure to follow the state of the ocean and inform public policies. But it still remains insufficient to fully meet the needs related to climate action, operational forecasts, digital ocean twins or sustainable ocean management and their resources.
Future efforts must aim to maintain and strengthen existing observation systems, while extending them to cover more complete all the physical, biogeochemical and biological dimensions of the ocean.
In priority, it will be:
- Develop observations in areas hitherto little covered, in particular observations in deep and polar waters;
- strengthen biogeochemical and biological observations so far less numerous and not very systematic;
- Improve the integration of ocean observations with ocean and climatic forecasting services in order to provide useful and usable information to decision -makers, economic players and coastal communities.
Finally, the sustainability of funding for long -term observation networks is a major challenge for the next decade. Without a lasting commitment, it will be difficult to maintain, adapt and develop these key infrastructure in the face of accelerating oceanic and climatic changes.
Refit the link between science and society to meet the challenges of the 21st century
Beyond research and politics, it is essential to raise awareness of the ocean so that society is better informed and aware of the links between ocean health, climate stability and human well-being.
To do this, global observation initiatives, for example adopt-a-float or Ocean Obomers, invite students, students and communities to follow oceanographic instruments and to contribute to environmental surveillance.
More generally, opening the doors of laboratories and putting science within everyone's reach is urgent.
As such, the collaboration between experts-scientific and journalists carrying information to the general public is a real issue, in particular in the current context of a society that is both superinformed, poorly informed and sometimes casual.
While thousands of scientists are at the bedside of the ocean health 24 hours a day, the continuous evolution of Goos, guided by scientific progress and political needs, will play an essential role in the construction of a lasting future and resilient for the oceans. A truly global and inclusive observation system, supported by collaborative governance and a fair allocation of resources, will be essential to meet the challenges and seize the opportunities of the XXIe century.
With an unwavering passion for local news, Christopher leads our editorial team with integrity and dedication. With over 20 years’ experience, he is the backbone of Wouldsayso, ensuring that we stay true to our mission to inform.
