Study: Nearly 1 billion trees threatened by California drought

SACRAMENTO -- While much of the country is dealing with rain and snow, California is still dry.

One hundred percent of the state is in some form of drought, and a new study just released by the Carnegie Institution for Science has now put a number on what the drought has done to California's iconic forests.

A high-tech flying laboratory has been soaring over California, measuring the impact of four years of drought.

"There's a lot of red on this screen, which is a sign that we're over an area that's in trouble," scientist Greg Asner told CBS News.

Asner says his team has made a startling discovery: 888 million trees in California's forests have seen measurable water loss since the drought began.

Basically, the drought has impacted nearly one billion trees in California.

They can be this precise because their plane is equipped with state-of-the-art lasers that scan 15 acres of forest every second. It's like having X-ray vision that produces first-of-their-kind 3D images of the health of every single tree in the forest.

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The Carnegie Institution for Science plane has lasers that produce 3D images detailing the health of the trees below

CBS News

The red areas show severely drought-stressed trees. Blue areas are healthier.

The equipment reads how much moisture is in each individual tree. "The measurement is focused on how much water is in the foliage itself," said Asner. "It's like getting a blood test. It's really one of the key indicators of the health of a tree."

The U.S. Forest Service says more than 29 million trees have already died. Asner's team has determined that 58 million more are on the brink.

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Greg Asner, right, looks at a map with a member of his team

CBS News

"We don't know whether a stressed tree is going to absolutely succumb and be gone or if it's going to bounce back over time," Asner explained.

The hope is that El Niño fueled storms will bring much needed rain. In the meantime, the new maps will help the forest service know which areas are most vulnerable, and wildfire officials know where the greatest risks are.