This is scientific American's 60 second science. I'm Christopher Intalyata. Got a minute?

Climate scientists forecast sea levels to rise anywhere from 1 to 4 feet by the end of the century. That's a pretty big range and

there's a good reason for that. There's a lot of uncertainty baked into climate

models. Take for example the way climate models predict how trees respond to drought.

Drought in these models is treated as a light switch either on or off.

But in the real world we know that drought can damage trees and that it takes some time for trees to repair this damage and recover.

William Andareg, an ecologist at Princeton University.

He and his colleagues examined tree ring data from more than 1,300 sites around the world.

And by comparing the rings with known drought records, they found that trees don't simply kick

back into gear as soon as rains return.

Drought actually puts the tree's water transport systems under a huge amount of tension, he says,

causing air bubbles to leak in, which damages or blocks those pipes.

I often compare this to a sort of a heart attack for a tree that in some cases it can be

lethal and in some cases they can repair that blockage.

And that drought hangover causes tree growth to lag 5 to 10 percent below normal for several years following a dry spell.

This is a problem because forests currently take up about 25 percent of human emissions of CO2,

which is an incredible break on climate change.

And the less CO2 the trees are able to take up, the warmer it gets.

The findings appear in the journal Science.

The thing this study makes clear is that predicting

climate change is hard. It's really hard. These models have a incredibly

challenging task of representing processes that occur from a leaf scale to a

...