Some 30 world leaders, officials and heads of worldwide organisations attended the summit by video link, and they agreed that protecting nature is key to human survival.
"Protecting 30% of the planet will undoubtedly improve the quality of life of our citizens, and help us achieve a fair, decarbonised, and resilient society", said Andrea Meza, minister of environment and energy for Costa Rica, which co-chairs the coalition with France and Britain.
We have been poisoning air, land and water - and filling oceans with plastics. "And now nature is striking back", he said, pointing to the Covid crisis as a case in point.
UN Secretary-General António Guterres told the summit that 2021 must be the year to "reconcile humanity with nature", and that the world can not afford to "revert to the old normal".
But he added that "biodiversity is facing a financial gap of $711 billion per year until 2030".
Key to protecting natural areas will be indigenous people, "the custodians of 80 per cent of the world's biodiversity", said Karl Burkhardt, Managing Director of One Earth initiative that is pushing for protecting 50 per cent of the planet.
"We can move the dial if we decide to do so".
Wildlife populations have plummeted almost 70 per cent in less than 50 years due to human activity, and scientists have warned that urgent efforts to restore and protect nature and biodiversity are required to prevent further destruction of ecosystems that support human life.
The aim of the meeting was to chart a path for the coming year in terms of joint climate action and biodiversity conservation.
Speaking at the summit via video link from Beijing, China's Vice-Premier Han Zheng called for global cooperation to protect the world's biodiversity.
Their boundaries also contain 28% of ocean areas that are most important to preserve global marine biodiversity, and more than a third of carbon stocks in the Earth's seas. "This year, against the backdrop of the COVID-19 pandemic, we must be innovative in our discussions", he said.
He also called on all parties to strengthen communication, meet each other halfway, and jointly promote the framework negotiation process; study and formulate the post-2020 action targets scientifically to ensure they are rational and enforceable; strengthen enforcement of resource mobilization and guarantees, and effectively enhance the implementation capabilities of developing countries. "We must accelerate talks on the post-2020 global biodiversity framework", he added.
The UN's next major climate summit, COP26, was also postponed because of the pandemic and is now due to be held in November.
"Obviously it is right to focus on climate change", said UK Prime Minister Boris Johnson.
"We have an enormous opportunity at this year's [UN COP15] Biodiversity Conference in China to forge an agreement to protect at least 30 per cent of the world's land and ocean by 2030", he said.
The chancellor added that Germany would join the "High Ambition Coalition for Nature and People (HAC)", a group of 50 countries committed to protecting 30% of land and sea habitats over the next 10 years to halt species extinction while addressing climate change issues.
Swedish climate activist Greta Thunberg threw cold water on the Paris meet in tweet, under the heading "LIVE from #OnePlanetSummit". He urged leaders to act decisively, stating that they have the means to tackle the crisis in the natural world.