It's the bean you really want in your morning Joe.

Sweet rather than bitter, flavoursome rather than overpowering, Arabica is strong but not too strong.

Yet scientists are warning that the world's favourite coffee is now at risk of extinction, at least in the wild.

The destruction of highland forests, climate change and pests are conspiring to kill off the coffea species in its native Ethiopia.

This despite the fact that its commercially planted relatives - thriving from Brazil to Java, now account for nearly two of of three cups of coffee drunk.

But it is not just Arabic that is at risk. Researchers at the Royal Botanic Gardens, Kew, have found that 75 of the world's 124 wild coffee species are endangered.

Dr Davis, lead author of the study said: "What we're saying is 60 per cent is just really high, that's a real wake-up call. For a major global commodity, that starts ringing alarm bells.

"It's a tragedy losing any wild species, whether it's a bird or plant or animal, that's bad enough.

"But when you've got a crop that supports the livelihoods of 100 million people just in production in coffee farming, then you look at value of high street coffee chains and supermarket coffee, it's enormous."

Coffea plants - the little flowering shrubs or trees which produce beans - were first cultivated in Ethiopia and native Yemen in the Middle Ages.

Europeans later picked up the habit from Arabs - coffee is from the Arabic qahwah - and transplanted coffea plants to their colonies in the East Indies and South America.

Arabica - along with its more bitter rival robusta - were the most common species.

Scientists, however, stress that wild coffea plants are still needed to develop and protect one of the world's most popular drink. Researchers are Kew, for example, have found African species which are naturally caffeine free. Wild plants may hold the secret of developing coffees that can survive climate change.

Coffee farmers, whether they grow Arabica or Robusta , have already begun to report their crops being affected by changing weather patterns, rising temperatures and new pests and diseases.

The variety of traits found in wild species are likely to be even more important in the future to develop plants that can cope with threats such as longer dry seasons caused by climate change or the spread of pests.

Kew's head of coffee research Dr Aaron Davis warned: "If you start to lose these species the options for developing resilient coffee for the future diminishes very rapidly."

Less than half of the wild coffee species are held in seed banks or living plant collections and more than a quarter are not known to occur in any protected areas, the scientists also warn.

They called for increased conservation in the natural environment as well as in seed banks and plant collections, and urged support for the African countries where most wild species are found to help them protect their coffee resources.

The new study, published in Science Advances, used criteria of the Red List of Threatened Species to measure the risk to coffee. The level of risk for coffee is much higher than for plants as a whole, with an estimated 22 per cent of plant species worldwide threatened with extinction.

A second study from Kew, published in Global Change Biology, looked specifically at wild Arabica, exports of which are worth more than £10 billion a year.

It found that when climate change was taken into consideration, wild Arabica, which is only found in the humid forests of Ethiopia and a small area of South Sudan, moves from being classed as "not threatened" to "endangered".

Kew's Dr Justin Moat, one of the authors of the paper, said: "These findings are so important as they indicate that the extinction risk to many other coffee species could be much worse if we consider climate change."