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Future greenhouse Earth. Artwork of the surface of Earth in about one billion years time. The Sun is predicted to have heated up, becoming 10% brighter as helium ash (from nuclear fusion of its hydrogen fuel) accumulates in its core. The temperature rise will raise Earth's atmospheric water content, trapping the Sun's heat in a moist greenhouse effect. Runaway temperatures will cause most of Earth's water to boil away. It is thought that water may remain in deep ocean trenches (blue, red and green, lower centre), sustaining heat-loving bacteria. The continuing heating of the Sun, and the loss of all water, will lead to a Venus-like, lifeless Earth in about 3.5 billion years time. (KEYSTONE/SCIENCE PHOTO LIBRARY/LYNETTE COOK)