Scientists across the country are expressing alarm as the Trump administration dismantles another tool for understanding how the planet is changing.

Starting this month, more than 900 deep-sea ocean sensors will be pulled out of the Pacific and Atlantic oceans off the coasts of Washington, Oregon, Alaska, North Carolina, and Greenland.

Researchers say these are some of the most critical ocean observation tools we have.

William Brangham's here now to explain the latest.

William, what are these sensors and why do researchers tell you they're so important?

This was a decades-long, about $380 million research project.

Hundreds of sensors, you described.

Some of them set on the surface of the ocean,

some of them went down hundreds of feet.

The way to think about this is like an ongoing medical checkup

on the health of the oceans.

How salty is it? How warm is it?

How do the currents move in the ocean? Where are they moving? How are the fish doing down there? How is the ocean responding to climate change?

I think it's hard to overstate just how critical oceans are to life on Earth. They regulate our weather. They provide food for millions of people all over the world. Over the last few decades,

they have absorbed an enormous amount of the carbon pollution that we put up in the atmosphere

has been taken up by the oceans, thus delaying some of the more negative consequences of climate change against us.

These sensors were looking at all of those things, and now we are, in essence, stopping that research project totally.

So if this is such an important project, what exactly is the Trump administration's rationale for dismantling it?

I wish I could give you a clear answer on this.

The National Science Foundation, which runs this, put out a statement justifying this that is incredibly hard to parse.

Let me just read this statement.

Here's what they said.

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