While dozens of world leaders have pledged to halt the devastating destruction of biodiversity across the planet, observers say political momentum has yet to filter into negotiations that will set the stage for a major UN meeting later this year.

Countries have proposed to hold an extra biodiversity meeting in Nairobi in June as talks in Geneva involving nearly 200 countries — although without the United States — entered their final day Tuesday without fully discussing some major topics.

Negotiators have held talks since March 14 to thrash out details of a sweeping plan to "live in harmony with nature" by mid-century — with key milestones in 2030 — that will be adopted at the United Nations COP15 conference in China later this year.

The task is a daunting one because biodiversity is undermined by a host of human activities from intensive agriculture and overfishing, to mining and rapid urbanisation.

"Biodiversity is not restricted to one place, it is everywhere, it is life," said Ghanaian academic Alfred Oteng-Yeboah, who has played a key role in international efforts to protect wildlife and species diversity.

The imperative to set goals that will be acted upon is even more urgent because the world missed almost all the targets that were set for the last decade.

"We think that this is the last chance that we have and if we miss it we don't know what is going to happen," said Oteng-Yeboah.

After two years of pandemic delay, the in-person negotiations seek to pack in both technical scientific work as well as high-level negotiations on the overarching targets.

Delegates have concluded they need more time and a document uploaded on the conference website suggests a new meeting in the Kenyan capital between June 21 and 26 to "continue negotiations" on the draft text and other issues.

The decision is subject to official approval by the Geneva meeting before it wraps up later Tuesday.

– Funding question –

While more than 90 nations have signed up to a pledge to halt biodiversity loss by 2030, delegates said the weight of that political will has not been felt at the negotiations in Geneva.

"There's a disconnect between the lofty rhetoric and actions we're seeing in the negotiations," said Brian O'Donnell, director of Campaign for Nature.

Ten days of intensive work allowed the delegations to put their ideas on the table, without managing to wrangle a consensus.

The UN's Convention on Biological Diversity has "gone through an unprecedented period in its history with the impact of the pandemic", said the organisation's executive secretary Elizabeth Maruma Mrema.

While the priority is to reach an ambitious agreement at COP15, several delegates said the negotiations had not yet wrestled with the most difficult issues.

"We have not talked a lot about the transformation of production, agriculture, urban planning," said one.

The most emblematic goal in the draft text is the protection of 30 percent of land and oceans by 2030 globally.

It is supported by a growing number of countries, but delegates cautioned that even that cornerstone target was not yet certain to be part of the agreement in Kunming.

Experts say that while the major targets are important, they will not achieve much without effective and fair implementation — and sufficient funding.

Developed countries accept that more money is needed — from national, international and private sources — but they have baulked at increasing funding to the level sought by poorer nations.

Since most of the world's remaining biodiversity is in the developing world, there is a need for richer countries to step up their financial help, said one delegate from Latin America.

But for real progress there needs to be greater political momentum going into COP15, which is expected to take place in late August.

"We need to make sure that the negotiators are getting clear instructions from the capital," said Marco Lambertini, WWF director general.