Attention at all passengers. You can now book your train tickets on Uber and get 10% back in Uber credits to spend on your next train journey.

So no excuses not to visit your in-laws this Christmas.

Trains now on Uber. T's and C's apply check the Uber app. This is

Scientific American's 60 Second Science.

I'm Christopher Intagata.

Greenland is the biggest island in the world

and the ice sheet that sits atop it is massive. is the

island in the world and the ice sheet that sits atop it is massive. The pile of ice is so thick that it extends more than 10,000 feet

above the ocean and if all that ice were to melt and go into the ocean

global sea levels would rise by 24 feet everywhere around the world.

Jason Briner a geologist at the University at Buffalo.

The ice sheet is melting of course, but just how much compared to the past.

Briner's team did a computer simulation of the southwest portion of the Greenland Ice Sheet, which he says is a pretty good proxy for ice melt across the entire ice sheet.

The researchers plugged past climate data into that model to hindcast rather than forecast the past activity of the ice sheet and they

then checked the model's predictions of the past shape and size of the ice by

looking at piles of rocks and boulders and dirt on Greenland today which outline the edges of ancient ice. and

the dirt on Greenland today, which outlined the edges of ancient ice. And the simulation was in good agreement with the actual situation.

Using that reconstruction of the ice sheet over time,

the team could then compare the ice sheet's historic losses to those happening today, under human cause global warming, and they determine that Greenland is on track to lose more ice this century than during any century in the past 12,000 years,

possibly four times as much ice. The results appear in the journal Nature.

Ultimately it's up to us how much ice actually melts.

You know humanity has the knob, the carbon knob and that knob is going to influence the rates of ice

...