‘Watching the Sea Rise’

Every day brings something new to report about the weather conditions of planet Earth. Scientists call it climate change, and they are studying it very closely. World leaders are discussing it. Students and teachers are learning about it. If weather conditions are going to change the Earth in a big way, then we want to know about it! We hear about glaciers and ice sheets melting. And we hear about the sea level rising higher and higher all over the Earth.

For now, let’s just talk about sea level rise. Did you know that the level of the sea has risen all over the world more than 3 millimeters per year since 1992? That’s a little bit more than 2 inches in 17 years. Two more inches of water over almost three-fourths of Earth’s surface is a lot of water!

How do we know this? Since 1992, NASA and the French Space Agency (called CNES) have been using satellites with radar to measure the height of the sea’s surface.

Radar is a device that uses radio waves to detect objects like airplanes. Only now we are using radar in a new way: to find out how high the sea level is rising. These radar devices are attached to satellites. A satellite is a man-made object that orbits the Earth. So the radar really gets a bird’s eye view of the whole planet.

Two things cause sea level to rise: First, scientists have been studying the temperature of Earth very closely, and they have found that Earth has warmed rapidly over the last 200 years. So the ocean is getting warmer too. Warming makes the water expand, which makes the sea level higher. Second, more water is being added to the ocean because glaciers and ice sheets are melting.

But, you’re probably wondering, “What’s the big deal about sea level rise? Two inches in 17 years doesn’t seem like very much.” But sea level has risen 6.7 inches in the last 100 years. In the last 10 years, it has risen twice as fast as in the previous 90 years. If Greenland’s ice sheet were to melt completely, sea level all over the world would rise by 5 to 7 meters (16 to 23 feet).

No one knows exactly how much the sea level will rise over the next century. Scientists want to know, “Will the sea level continue to rise? And if it does, how will that change the Earth?”

A scientist needs to ask a lot of questions. And even more important, a scientist needs to be able to figure out the answers to those questions. That’s where you come in. We need many more new scientists to help answer questions about our changing planet. For that a scientist needs to have a reasoning mind. Could you be one of them?

You can create your own map of the bumps in the ocean, then eat the map for dessert! Check out the “El Niño Pudding” page at

This article was provided through the courtesy of the Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, under a contract with the National Aeronautics and Space Administration.

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