The Earthshot Prize will be awarded to five people every year over the next decade, and aims to provide at least 50 answers to some of the greatest problems facing the planet by 2030.

They include promoting new ways of addressing climate change and issues surrounding energy, nature and biodiversity, the oceans, air pollution and fresh water.

The prize, inspired by US president John F. Kennedy's ambitious "Moonshot" lunar programme in the 1960s, promises "a significant financial award", a statement said.

William, a grandson of Queen Elizabeth II and second in line to the throne after his father Prince Charles, said the Earth was "at a tipping point" and faced a "stark choice".

"Either we continue as we are and irreparably damage our planet or we remember our unique power as human beings and our continual ability to lead, innovate and problem-solve.

"Remember the awe-inspiring civilisations that we have built, the life-saving technology we have created, the fact that we have put a man on the moon. People can achieve great things.

"The next 10 years present us with one of our greatest tests -- a decade of action to repair the Earth," he said.

The award, which will be launched later next year and be bestowed from 2021, is open to individuals as well as to communities and businesses.

It has the backing of conservation campaigners, groups and scientists, including the veteran British natural history broadcaster David Attenborough.

"The spirit of the Moonshot can guide us today as we confront the serious challenges we face on Earth," Attenborough said in a film to mark the launch.

"This year Prince William and a global alliance launch the most prestigious environment prize in history... designed to motivate and inspire a new generation of thinkers, leaders and dreamers to think differently."

Both William's father and his grandfather, Prince Philip, have campaigned for environmental causes and against the illegal trade in wildlife around the world.

The young royal is hoping to build on their work through the prize, which will initially be run by his and his wife's own charitable foundation.