According to an analysis by experts from around the world, the ecologically extremely important coral reefs are under considerable threat.
Compared to a status report from 2008, the situation has deteriorated further, said the chairman of the conference, Bremen marine biologist Christian Wild, on Friday at the end of the 14th International Coral Reef Symposium ICRS.
The five-day conference with around 1,300 experts from 80 countries was organized digitally by the University of Bremen.
In a strategy paper developed by the International Coral Reef Society, the conference called for swift action.
She urged three measures to save the reefs.
The focus is on combating climate change, improving local living conditions for corals and actively reforesting reefs.
The paper is aimed at decision-makers in all countries from politics, administration, business and civil society.
Like tropical rainforests, coral reefs are part of the ecosystems of global importance.
Their occurrence extends along the equator between the 30th parallel north and south around the whole earth.
"Their economic value is 10 trillion US dollars a year," said Sebastian Ferse from the Leibniz Center for Tropical Marine Research in Bremen, who helped organize the conference.
Around 600 million people are economically directly dependent on functioning coral reefs.
Coral bleaching is a major threat to the reefs.
In most cases it leads to extensive death of the reef-forming corals and thus to the destruction of large ecosystems.
A key trigger for coral bleaching is global ocean warming, which is directly attributable to climate change.