Visitors attend the launch of The Blue Paradox, an immersive experience exploring the ocean plastic pollution crisis hosted by SC Johnson in partnership with Conservation International at Exhibition London, the UK, on Tuesday. Photo: VCG

A long-delayed UN conference on how to restore the faltering health of global oceans kicks off in Lisbon, Portugal Monday, with thousands of policymakers, experts and advocates on the case.

Humanity needs healthy oceans. They generate 50 percent of the oxygen we breathe and provide essential protein and nutrients to billions of people every day.

Covering more than two-thirds of Earth's surface, the seven seas have also softened the impact of climate change for life on land. 

But at a terrible cost.

Absorbing around a quarter of carbon dioxide pollution - even as emissions increased by half over the last 60 years - has turned seawater acidic, threatening aquatic food chains and the ocean's capacity to pull down carbon. 

And soaking up more than 90 percent of the excess heat from global warming has spawned massive marine heat waves that are killing off precious coral reefs and expanding dead zones bereft of oxygen.

"We have only begun to understand the extent to which climate change is going to wreak havoc on ocean health," said Charlotte de Fontaubert, the World Bank's global lead for the blue economy.

Making things worse is an unending torrent of pollution, including a garbage truck's worth of plastic every minute, according to the UN Environment Programme (UNEP). 

On current trends, yearly plastic waste will nearly triple to 1 billion tons by 2060, according to a recent OECD report.

Microplastics - found inside Arctic ice and fish in the ocean's deepest trenches - are estimated to kill more than a million seabirds and over 100,000 marine mammals each year.

Solutions on the table range from recycling to global caps on plastic production. 

Global fisheries will also be under the spotlight during the five-day UN Ocean Conference, originally slated for April 2020 and jointly hosted by Portugal and Kenya. 

"At least one-third of wild fish stocks are overfished and less than 10 percent of the ocean is protected," Kathryn Matthews, chief scientist for US-based NGO Oceana, told AFP.

"Destructive and illegal fishing vessels operate with impunity in many coastal waters and on the high seas."

One culprit is nearly $35 billion in subsidies. Baby steps taken last week by the WTO to reduce handouts to the industry will hardly make a dent, experts said.

The conference will also see a push for a moratorium on deep-sea mining of rare metals needed for a boom in electric vehicle battery construction.

Scientists say poorly understood seabed ecosystems are fragile and could take decades or longer to heal once disrupted.

Another major focus will be "blue food," the new watchword for ensuring that marine harvests from all sources are sustainable and socially responsible. 

AFP