British broadcaster Sir David Attenborough is leading a call from conservation groups for the world to invest $US500 billion ($700 billion) a year to halt the destruction of nature.

Sir David, whose latest film documents the dangers posed by climate change and the extinction of species, issued the call as the United Nations convened a one-day summit aimed at galvanising action to protect wildlife.

“Our natural world is under greater pressure now than at any time in human history, and the future of the entire planet – on which every single one of us depends – is in grave jeopardy,” Sir David, 94, said in a statement on Thursday (Australian time).

“We still have an opportunity to reverse catastrophic biodiversity loss, but time is running out.”

Opening the summit in New York, UN Secretary-General Antonio Guterres warned that a million species were at risk of extinction and that climate change and the loss of biodiversity were “destroying earth’s web of life”.

“We are part of that fragile web and we need it to be healthy so we and future generations may thrive,” Mr Guterres said.

Humanity is waging war on nature.

We need to rebuild our relationship with the natural world – to avert the worst impacts of the climate crisis and recharge biodiversity for the benefit of people and the planet.#ForNature https://t.co/nO573PQy9K pic.twitter.com/hv1DJXkN8F

— António Guterres (@antonioguterres) September 30, 2020

The call to redirect financing away from fossil fuels and other polluting industries and into locally led conservation was launched by environmental group Fauna & Flora International and backed by more than 130 organisations.

The world spends an estimated $US80-90 billion ($112-125 billion) on conservation each year, but studies show that hundreds of billions of dollars may be needed to save ecosystems from collapse.

The climate emergency is fully upon us, and we have no time to waste.

The answer to our existential crisis is swift, decisive, scaled up #ClimateAction – with at least a 45% reduction in greenhouse gas emissions below 1990 levels by 2030, and net zero emissions before 2050. pic.twitter.com/DzTu1nS7CY

— António Guterres (@antonioguterres) September 30, 2020

Britain, Canada and others joined the European Union on Monday in pledging to protect 30 per cent of their land and seas by 2030.

UN officials hope to secure a global agreement on that target at a major round of negotiations on biodiversity due to take place in China in 2021.

-AAP