World Not Ending Soon

Two scientists in the United States say life on Earth may go on much longer than some now believe. Ken Caldeira and James Kasting believe that life on Earth has up to 1,500 million more years to go. Much longer than the British scientists proposed ten years ago. James Lovelock and M. Whitfield said that life on Earth will end in 100 million years.

Mr. Lovelock and Mr. Whitfield said that in about 5,000 million years the sun would burst into a giant red star. But long before that, the sun will get brighter, warming the Earth. As the Earth warms, silicate rocks would remove carbon dioxide from the air.

They said that in about 100 million years so little carbon dioxide would be left that plants would starve. If the plants starve, all other forms of life on Earth would die. Finally, they said, Earth would become like Venus. On Venus, the air is hot enough to melt lead.

The new study by Mr. Caldeira and Mr. Kasting appeared in the British publication, Nature. They do not dispute that the sun is getting hotter. But they believe that the temperature od the Earth's atmosphere will not rise much for 900 million years.

Mr. Caldeira and Mr. Kastings say that newer forms of plants, including corn, need less carbon dioxide in the air to survive. They say plants and trees will survive 500 millions more years. Grasslands and cornfields will survive almost 1,000 million years before the planet becomes like Venus.

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