Paris (AFP)

Even if it has damaged the oceans, humans can hope to find solutions to fight against climate change and its impacts, provided it protects its weakened ecosystems.

From marine renewable energies to the restoration of coastal ecosystems, "the ocean is also a source of solutions that should be implemented", argues Jean-Pierre Gattuso, a CNRS researcher who participated in a study on the subject published in 2018 in the journal Frontiers in Marine Science.

Restoration and protection

Global warming, overfishing, pollution ... The ocean is sick, at the risk of not being able to ensure as effectively activities essential for the survival of humanity, such as the production of oxygen and the absorption of CO2 from activities human.

To help him regain his strength, many advocate for an increase in protected areas.

"At least 30% of the oceans must be placed under protection for ecosystems to be sufficiently resilient (...) and the remaining 70% must be managed in a prudent and sustainable manner," says Tom Dillon, vice president of the NGO Pew Charitable Trust.

According to the recent report by UN experts on biodiversity, 7% of the seas are now protected, and not necessarily effectively.

Protecting the oceans also means restoring coastal ecosystems such as mangroves or seagrass beds, which have significant carbon absorption capacity, a phenomenon known as "blue carbon".

The climate change mitigation potential of these ecosystems is "relatively modest globally (about 2% of emissions)," according to the UN climate experts' draft report discussed starting this Friday in Monaco.

But it's still better than nothing, especially if it is in good health, this marine vegetation also allows to "reduce the impacts of the rise of the sea level" and offers "co-benefits to the local communities "(food security, tourism ...), notes the study of Frontiers in Marine Science. Preserving them also reduces the emissions caused by their degradation.

Renewable energies

Marine renewable energies come from the wind (offshore wind turbines) or directly from the ocean, by waves, tides or currents.

In a study published in 2017, researchers at the Carnegie Institution for Science estimated that offshore wind farms would produce more energy than those installed on land, and even calculated that parks all over the North Atlantic could respond. to the current needs of humanity.

"It's a vision of the mind, it will never happen, but it shows the potential of this technique not sufficiently implemented," commented Jean-Pierre Gattuso.

In general, marine renewable energies are an "extraordinarily effective solution that could be put in place right away," he says, noting, however, the difficulties of developing technologies adapted to a "hostile environment" such as the 'ocean.

Geoengineering

Some scientists dismiss them immediately as sorcerer's apprentice techniques, highlighting the risks they imply, others work on geo-engineering, convinced that working on the only reduction of greenhouse gas emissions greenhouse will not be enough to protect the planet.

Part of these climate manipulation techniques are ocean-related, like fertilization. This involves introducing soluble iron into the sea to boost the production of phytoplankton that absorb CO2 during photosynthesis.

But some fear side effects. Even critical for other techniques like the idea of ​​deploying a large white foam on the surface of the oceans to reflect the sun's rays.

Other technologies are a bit more advanced, such as carbon capture and storage. Some companies are working to store CO2 at the bottom of the sea or under the oceans.

© 2019 AFP