Today is the final day of the UN Ocean Conference, which has seen hundreds of leaders, activists and scientists descend on the Portuguese capital, Lisbon, to work on solutions to restore the ocean’s health and protect its future. A large part of this will be to scale up ocean action based on science and innovation for the implementation of Sustainable Development Goal 14: Life Below Water.

Life in the ocean makes up the vast majority of the planet's biosphere. It covers 70 per cent of the Earth’s surface, and is home to up to 80 per cent of all life in the world. It nurtures unimaginable biodiversity, produces food, and provides jobs, mineral and energy resources needed for life on the planet to survive and thrive.

The ocean is of course vast, and the threats it faces are myriad and complex: from overfishing and dumping of toxic waste and plastic waste to rising sea levels and increased acidification, The ocean is also is a major part of the planet’s climate system, and must be protected if it is to play a critical role in regulating our climate.

Andrew Hudson is the head of Head of the United Nations Development Programme’s Water and Ocean Governance Programme, and a man deeply familiar with both the ocean’s importance to humanity and the challenges it is currently facing.

He mentions four big issues around the ocean: sea level rises, ocean acidification, ocean deoxygenation, and ocean warming.

Hudson uses global warming to illustrate the importance of the ocean to the survival of humankind. “91 per cent of the extra heat caused by climate change is absorbed by the ocean and 7 per cent by the atmosphere."

Ocean warming accounted for 91 per cent of the heating in the climate system, with land warming, ice loss and atmospheric warming accounting for about 5 per cent, 3 per cent and 1 per cent, respectively.

 "The atmosphere has warmed about 1 degree so far. If that 7 per cent caused one degree of warming, and the other 93 per cent is in the ocean [the top 700m of which has also warmed up about one degree. It is more difficult to measure below that on a global scale], imagine if we didn’t have the ocean?" Without the ocean, Hudson explains, global warming would already be far beyond manageable levels.

“The pH level of the ocean – its acidity level – has been remarkably stable for tens of millions of years, having a pH level of about 8.2, or 8.3. In the past hundred years of industrialization, we have knocked that down by 30 per cent; so, the ocean is 30 per cent more acidic than it was 50 or 100 years ago,” Hudson says.

“The ocean has not acidified this fast or close to this fast for 55 million years.” And, 55 million years ago was not a great time to be on the planet. “That event was associated with a huge mass extinction on Earth, particularly of marine species. This is an indicator of how important and how profound this change is to the ocean.”

This rising acidification affects the ocean in a number of ways. Firstly, shell-forming animals such as corals, oysters, crabs and urchins are unable to form shells when the water is too acidified.

Scientists have already seen evidence of this in Antarctica’s Southern Ocean, where due to the water being colder, the ocean’s acidity level is rising faster – due to the C02 dissolving faster – than elsewhere in the world. “We see that Pteropods (tiny planktonic sea snails) ­– which are a key part of the food chain ­– are already experiencing difficulty forming their shells, and have deformed shells in some instances, which really is a canary in the coalmine. Ocean acidification an existential threat to some very important organisms in the ocean.”

While these organisms may be small, they are an important part of the marine ecosystem. “If certain species go extinct that would ripple up and down the food chain. So, for example, zooplankton feed on phytoplankton, which are fed on by small fish and larger organisms, so any extinction would lead to complete restructuring of some marine ecosystems, ultimately simplifying and making the ecosystem less complex and less resilient.”

Despite the doom and gloom around the ocean, Hudson is optimistic that change is possible, and indeed is happening right now. “Every positive step towards the Paris Agreement has a corresponding effect on the ocean: it reduces the rate of ocean acidification, it reduces the rate of ocean warming and it reduces the rate of ocean deoxygenation.

“Recently, we saw the UNEA Convention on plastics and the introduction of Extended Producer Responsibility in Europe [where producers are responsible for the entire life cycle of the products that they introduce on the market, from their design until end of life including waste collection and recycling], both of which are very positive steps.”

UNDP too has been making changes. “We are taking part in UN’s Greening the Blue initiative [which is supported by the UNFCCC], and we have been offsetting which is fine, but we made a commitment to literally reduce our emissions by 50 per cent by 2030. We have been investing a couple of million or more each year, so we have lowered facilities GHG emissions by 8 per cent and are also working on reducing emissions from mission travel and vehicles.”

Hudson also cites the importance of the UN Ocean Conference. “It raises the ocean’s profile, it helps get a lot of attention and it increases political ambition around the ocean,” he says. “There are also hundreds of side-events happening that share good practice and build partnerships.”

Given the multiple, interconnected threats the ocean now faces, it’s never been more important to use whatever tools we have to save them – and ourselves.