The planet is drying at an unprecedented pace, presenting a critical threat to humanity.

That's according to a new study published in the journal Scientific Advances.

Researchers found that continental drying is having profound global impacts that threaten water availability across the globe.

For part of our tipping point coverage, I spoke recently with Abram Lustgarten,

climate investigations editor at ProPublica, and began by asking him why so much of the earth is

drying out. It's a mixture of climate change and a massive overuse of water resources by people

that appears to be drying out the continents, according to a new study

out of Arizona State University.

And it basically found that rising temperatures are leading to less precipitation in certain places

and faster evaporation from both the soil and from rivers and surface waters.

At the same time that over pumping of groundwater aquifers is quickly

depleting the resources that are held in those underground reservoirs.

Who's driving this problem?

It's difficult to parse out the difference between climate change as in effect and the

human over pumping of groundwater, but those are the two factors.

And of course, it's the emissions from the burning of

fossil fuels that is driving the rising temperatures on the planet. And so that is really contributing

to a water loss or a water reportioning across the globe. And the groundwater pumping is driven

by individual use, by farmers, by corporations, by cities

around the world.

It is becoming the fallback kind of bank account, if you will, of water resources that people

and groups are turning to as their surface waters are diminished or as droughts deplete those

...