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Why does global warming cause ocean levels to rise? Wouldn’t the extra heat make the water evaporate?

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Dear Tom,
Why does global warming cause ocean levels to rise? Wouldn’t the extra heat make the water evaporate?
— Salome, Batavia
Dear Salome,
The amount of water that can be stored in the atmosphere (as water vapor) is minimal compared with the total amount of water on the planet. Meteorologists use “precipitable water” to measure the total amount of water vapor in the atmosphere above a point, and that value is rarely above 3 inches. Even if the entire atmosphere’s precipitable water were at that extreme level, the atmosphere would contain only 3 inches of water, an amount equal to sea level rise in just the past 35 years. Water from melting ice on land and increased water volume in the oceans from a gradually warming world ocean account for the rising sea level, and the rise continues (and the rate of rise is itself increasing).

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