Oceanographer Josh Willis from NASA's Jet Propulsion Laboratory narrates this video about the causes of sea level rise and how sea level has changed over the last two decades as observed by the Jason series of satellite missions.


Hi, I'm Josh Willis the project scientist for the Jason-3 missions to measure sea level rise from space.

In some ways, sea level rise is really simple. As water heats up it takes it more room. This drives sea level rise, and in addition, as glaciers and ice sheets are melted, extra water is added to the ocean just like when you turn on your faucet in the bathtub.

Over ninety percent of the heat trapped by greenhouse gases is being absorbed by the oceans. When that happens, sea water expands and this helps drive sea level rise.

Hundreds of millions of people around the world live on coastlines that can be threatened by rising seas. This animation shows how sea levels have changed over the last 23 years. Globally, sea levels have gone up by about six centimeters during that time.

But it doesn't happen all at the same speed everywhere. Some places are rising faster than others, and some places are even falling. Orange and red colors mean that sea levels have gone up in these locations. And blue and white mean sea levels stayed the same or actually fallen.

You can see that most places in the ocean are orange meaning sea levels have risen over the last 23 years. In a few places, you can see blue where sea level has actually dropped. He we see the Gulf Stream. The red and blue indicate that this massive current has shifted slightly in the last 23 years.

Off the west coast of the United States, we've seen sea levels actually drop. This is because waters there have been cooling because of something called the Pacific decadal oscillation.

In the Western Pacific, sea levels have been rising very rapidly. This is because heat is being pushed from east to west across the Pacific.

Sea level rise is going to be a major impact of human caused climate change. And here at NASA, we're doing everything we can try to better understand it.

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