Biodiversity is under dire threat from global warming, habitat loss, pollution and over-exploitation, all largely the fault of humans, the head of world-renowned Kew Gardens said on Thursday.

"First-aiders always check the ABC - Airway, Breathing and Circulation - of a patient to see if anything needs immediate attention," Stephen Hopper said in an interview in his office overlooking the lush Royal Botanic Gardens at Kew, west London.

"Biodiversity is the ABC of life on the planet - and it is showing it is in deep trouble," he told Reuters.

World experts will gather in Germany next month to try to work out what to do to stop the dramatic increase in the rate of loss of plants, animals and insects in what many see as the start of the sixth great species wipe-out in the Earth's history.

The last one was in the age of the dinosaurs which first appeared 230 million years ago and dominated the Earth for 100 million years. By comparison, human domination has so far lasted the equivalent of the blink of an eye.

"The challenge for us is to find a way of slowing down or preferably stopping all this destruction. We need to ensure the maximum options for the future," Hopper said.

"Globally we use 30,000 species of plants as edible but we base most of our western agriculture on just a dozen. As the environment changes, who knows which of the other 29,988 are going to emerge as the most important in a future world?"

A species of food crop that produces bounty now may be rendered useless in the future because of climate change-induced droughts, floods or changes in soil salinity or acidity.

Many modern medicines are derived from plants and new uses are being discovered regularly to treat cancers, pain and organ failure, among a host of ailments, Hopper said.

The animal world is also being exploited for food and medicines, but the threat there is no less significant than for plants. Humans shouldn't imagine that the planet and its abundance of life is all theirs for the taking, he said.

"There is that utilitarian argument. But there is also another about our ethical responsibilities. We share this planet with other species. Surely they have a right to exist as much as we do," said Hopper.

"Then there is another aspect that I think is very important to many people. The sheer joy and wonderment of the natural world. It is a bit like walking in the garden here. Most people's shoulders tend to relax a bit and unwind."

Kew is doing its part through the Millennium Seed Bank project, which is well on the way to collecting and storing safely 10 percent of the world's wild plants.

The next goal - as yet a wish without any financial backing - is to raise that total to 25 percent by 2020.

Not only may they be used at some stage in the future to repopulate decimated plant populations in the wild but they might also one day come into their own as sources of new foods, medicines, fuels or even clothes.

Zoos around the world are making similar efforts to conserve members of the animal kingdom through sperm and egg banks.

"I am an optimist," Hopper said. "We may have already lost a lot but we are capable of protecting what is still left out there. But we have to act quickly to stop climate change and end habitat loss. We only have a few decades to make a difference."

"I for one want to leave a living planet for our children."