Christopher Joyce

A rain forest sings with the sounds of insects, birds, maybe a howler monkey or two. But scientists are discovering that some forest dwellers also communicate in ways humans usually can't hear — via ultrasound.

A team from Dartmouth College has recorded these signals in treetops on a pristine Panamanian island called Barro Colorado, and slowed them down to make sense of them.

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Here in Washington this week, President Trump signed an order to start undoing some key climate change regulations. The president says they're hurting business.

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Sea ice in the Arctic has been melting at a record-breaking pace. Scientists blame a warming climate for most of that, but researchers have now teased out a natural cycle for how Arctic sea ice melts year-to-year.

Based on that cycle, they conclude that 30 percent to 50 percent of the melting is due to natural causes, while human-caused warming is responsible for the rest.

Wildfires can start when lightning strikes or when someone fails to put out a campfire. New research shows that people start a lot more fires than lightning does — so much so that people are drastically altering wildfire in America.

Fire ecologist Melissa Forder says about 60 percent of fires in national parks are caused by humans: "intentionally set fires, buildings burning and spreading into the forest, smoking, equipment malfunctions and campfires."

An "atmospheric river" is a colorful term for a sinuous plume of moisture that travels up from the tropics — a single plume can carry more water than the Mississippi River at its mouth. But new research shows that atmospheric rivers are also among the most damaging weather systems around.

The atmospheric rivers that soaked California this winter did some good — they ended an epic drought in the state.

The Mariana Trench in the northern Pacific is the deepest part of the world's oceans. You might think a place that remote would be untouched by human activity.

But the Mariana Trench is polluted.

At its deepest — about 7 miles down — the water in the trench is near freezing. The pressure would crush a human like a bug. Scientists have only recently explored it.

This week, President Trump's transition team put new restrictions on government scientists' freedom to communicate. The restrictions are being characterized as temporary, and some have already been lifted.

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It's been more than 10 years since the U.S. was hit by a major hurricane. Scientists mark that up to chance. But as NPR's Christopher Joyce reports, new research suggests a reason for our good fortune.

There's more methane gas in the atmosphere than there used to be, by every scientific measure. The Obama administration has been trying to stem the increase of this powerful greenhouse gas, but the incoming Trump administration appears bent on keeping the government's hands off methane.

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