A closing plenary session, scheduled for 6 p.m. Colombian time, had not started more than three hours later as smaller groups of negotiators huddled behind closed doors in a bid to iron out their differences.

The 16th Conference of Parties (COP16) to the United Nations' Convention on Biological Diversity (CBD) opened on Oct. 21 and was scheduled to close Friday, though many are now steeling themselves for a late night. 

The conference, the biggest-ever meeting of its kind with some 23,000 registered delegates, is a follow-up to an agreement reached two years ago in Canada.

The Kunming-Montreal Global Biodiversity Framework that emerged from COP15 identified 23 targets to halt humankind's rapacious destruction of nature's bounty.

These included placing 30 percent of land and sea areas under protection and 30 percent of degraded ecosystems under restoration by 2030, reducing pollution, and phasing out agricultural and other subsidies harmful to nature.

It had agreed on $200 billion per year to be made available to protect biodiversity by 2030, including $30 billion per year from rich to poor nations.

COP16 was tasked with assessing, and accelerating, progress.

But negotiations on funding have failed to advance, observers and delegates say, even as new research presented this week showed that more than a quarter of assessed plants and animals are now at risk of extinction.

The Colombian presidency of the summit proposed a raft of last-minute draft texts for negotiators to consider as a way to end the stalemate.

One option was for talks on financing to continue after the summit, and until the next one in Armenia in 2026, to find a "comprehensive financial solution to close the finance biodiversity gap."

Such talks would also assess the viability of creating a new, dedicated biodiversity fund; a key demand from developing countries who say they are not represented in existing mechanisms, which are also too onerous.

Another point of contention is on how best to share the profits of digitally sequenced genetic data taken from animals and plants with the communities they come from.

Such data, much of it from species found in poor countries, is notably used in medicines and cosmetics that can make their developers billions.

COP15 in Montreal had agreed on the creation of a "multilateral mechanism" for sharing the benefits of digitally sequenced genetic information, abbreviated as DSI, "including a global fund."

But negotiators still need to resolve such basic questions as who pays, how much, into which fund, and to whom the money should go.

In a draft text for negotiators, the COP16 presidency proposed creating a new "Cali Fund" for the equitable sharing of DSI benefits.

Negotiators also remain stuck on the nature of a mechanism for monitoring progress toward the UN goals.

'Everyone has to cede'

On Thursday, Colombian environment minister and COP16 president Susana Muhamad said the negotiations were "very complex."

UN chief Antonio Guterres, who stopped over in Cali for two days this week with five heads of state and dozens of ministers to add impetus to the talks, reminded delegates that humanity has already altered three-quarters of Earth's land surface and two-thirds of its waters.

"The clock is ticking. The survival of our planet's biodiversity, and our own survival, are on the line," he said.

Representatives of Indigenous peoples and local communities held demonstrations at COP16 to press for more rights and protections as delegates inside wrangled over a proposal to create a permanent representative body for them under the Convention on Biological Diversity.

On this, too, no agreement has been reached after nearly two weeks of talks.

The meeting was held amid a massive security deployment following threats from a Colombian guerrilla group with its base of operations near Cali.