All forms of animal and plant life will disappear from the Earth within the next 2.8 billion years, due to the presence of too little carbon dioxide in the atmosphere, says a study conducted by the astrobiologist Jack O'Malley James of the University of St Andrews.

The study also revealed that microbes will be the dominant life-form as they have the ability to survive on a hotter Earth with minimal levels of carbon dioxide.

"The far-future Earth will be very hostile to life by this point. All living things require liquid water, so any remaining life will be restricted to pockets of liquid water, perhaps at cooler, higher altitudes or in caves or underground. This life will need to cope with many extremes like high temperatures and intense ultraviolet radiation and only a few microbial species known on Earth today could cope with this," said James.

According to the researchers, increased evaporation rates and chemical reactions with the rainwater would lead to loss of carbon dioxide and depletion of oxygen, resulting in the disappearance of the plants and animals.

The main cause for the possible disappearances of plants and animals will be the Sun. As the sun gets older, it will become hotter, warming other planets and leading to the evaporation of the oceans.

The hot surface will be difficult even for microbes to survive, only the most hardy life forms who find pockets of water in higher, cooler spots may be able to exist.

The study also said that while researching other inhabitant planets, scientists should concentrate on other forms of living organisms rather than focusing on higher life-forms that we are used to seeing around us because life on other planets evolved billions of years ago and its inhabitants might be now unrecognizable to us.

"Life in the Earth's far future will be very different to this, which means, to detect life like this on other planets we need to search for a whole new set of clues," O'Malley-James added.

"We have now simulated a dying biosphere composed of populations of the species that are most likely to survive to determine what types of gases they would release to the atmosphere. By the point at which all life disappears from the planet, we're left with a nitrogen:carbon-dioxide atmosphere with methane being the only sign of active life," James said.