CCC Stability and Change Liquid water has existed on Earth's surface for at least 4 billion years, even as the sun's energy output has continued to increase. The total area of continents (now 39% of Earth's surface) may have grown in size over Earth's history. Think about what you know about the albedos of land and water. Does an increase in land area explain why Earth's surface hasn't heated to a point that the ocean has boiled away? Why or why not?