The one-day event had been scheduled to take place in the southern French port city of Marseille in 2020, but was postponed due to the coronavirus pandemic.
Addressing world leaders at the One Planet Summit, the United Nations chief said that the process of recovery from the coronavirus pandemic offers the chance "to change course, and put humanity on a path on which it is not in conflict with nature", while urging greater efforts by everyone to protect biodiversity and step up climate action.
Indigenous peoples in particular are wary over the proposed expansion of protected areas, pointing to cases in Africa and Asia where such measures have led to eviction from their ancestral lands.
But the global community has not met any of its biodiversity targets set for 2020, and biodiversity is facing a financing gap of 711 billion US dollars per year until 2030, the United Nations chief said.
United Nations Secretary-General Antonio Guterres on January 11 called for greater efforts to protect biodiversity and step up climate action.
"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.
About 30 leaders, government officials and heads of global organizations were participating in the One Planet Summit on Monday, which was being held by videoconference because of the coronavirus pandemic.
"On the other hand, the Covid-19 pandemic has shown even more clearly that the biodiversity crisis is a major political issue".
The French leader said the world is seeing the impacts of overexploitation of natural resources including rising poverty, inequality, public health crises and security concerns.
What issues were on the summit agenda?
Promoting agroecology - a term describing a more sustainable way to grow food. "This year, against the backdrop of the COVID-19 pandemic, we must be innovative in our discussions", he said.
The 50 countries that joined the High Ambition Coalition for Nature and People together hold 30% of global terrestrial biodiversity and 1/4th of the world's terrestrial carbon stores, and 28% of ocean diversity, according to Campaign Fortunate Organization.
Around 30 leaders, government officials and heads of global organizations were scheduled to attend. China will be represented by Vice Premier Han Zheng.
U.S. president-elect, Joe Biden, who does not take office until 20 January, pledged during his campaign to better preserve 30 per cent of American lands and waters by 2030.
"We know there is no pathway to tackling climate change that does not involve a massive increase in our efforts to protect and restore nature", United Kingdom environment minister Zac Goldsmith said.
Other notable absences included the leaders of Russia, India and Brazil.
The Prince of Wales is also addressing the One Planet Summit, urging the private sector to sign up to a Terra Carta, or Earth Charter, to safeguard the Earth by adopting sustainability and investing 10 billion dollars (£7.3 billion) in "natural capital" such as clean air and water and fertile soils.
So far there have been meetings in Paris in 2017, NY in 2018 and Nairobi in 2019.
UK Prime Minister Boris Johnson said the UK will commit at least GBP 3 billion (USD 4 billion) to climate change solutions that protect and restore nature and biodiversity over five years.