Thursday, September 18, 2014

Another Paper Confirms Greenland's Accelerating Ice Loss

Here's a plot about Greenland's ice, from a recent paper in The Cryosphere by Hurkmans et al.

But note that the y-axis isn't the amount of ice in Greenland, it's the rate of change of the amount of ice, dM/dt.

In other words, it's the acceleration of ice loss. Eyeballing it, it looks like a change of about 325 Gt/yr in 13 years, or an acceleration of about 25 Gt/yr2, in agreement with Enderlin et al 2014 (27.0 ± 9.0 Gt/yr2 since 2000) and Wouters et al 2013 (25 ± 9 Gt/yr2).

It doesn't seem like much, but: if the melt rate for 2008 were to continue to 2100, with no acceleration, the loss in ice would be about 25,000 Gt, or 1% of Greenland's 2.6 M gigatons of ice. And it'd be another 1% for each century that goes by.

But with an (constant) acceleration of 25 Gt/yr2, the loss in 2100 will 106,000 Gt, or 4% of Greenland's ice, if I did the math correctly.

With the same acceleration, 18% of Greenland's ice would be gone by 2200, 74% by 2400, and all of it before 2500 -- 7.2 meters (24 ft) of sea-level rise. And that's with the same acceleration as today, which, given the world's trajectory, doesn't seem likely.

Greenland's ice gone in 400-500 years at most. Coastal cities mostly underwater. Is that a tragedy, or is it something worse?

9 comments:

charlesH said...

what is the temp trend in Greenland?

charlesH said...

Do you think temp is a leading, coincident, or lagging indicator for ice melt?

David Appell said...

"Do you think temp is a leading, coincident, or lagging indicator for ice melt?"

I think ice melts when the temperature is above the freezing point of water.

David Appell said...

"what is the temp trend in Greenland?"

http://bit.ly/1syZFzj

Dano said...

IMHO our population will have undergone a major downward adjustment by the time 24m SLR happens. Population biology is a b!tch.

Best,

D

David Appell said...

I agree about population -- if nothing else, even the poorest will (hopefully) be less poor in the future, with more access to medical care, so they'll likely have fewer babies. But this story came out the other day:

"A World With 11 Billion People? New Population Projections Shatter Earlier Estimates," National Geographic 9/18/14

http://news.nationalgeographic.com/news/2014/09/140918-population-global-united-nations-2100-boom-africa/

Dano said...

I saw that David. IMHO demographers need to start working in teams with population biologists, ecologists, agronomists, etc and come up with a multidisciplinary "likely" population under different scenarios.

I think the agronomists cr*p their pants when asked to come up with a plan to feed 9B, let alone 11B.

Best,

D

David Appell said...

Dano: Great minds think alike:

On the Path Past 9 Billion, Little Crosstalk Between U.N. Sessions on Population and Global Warming
By ANDREW C. REVKIN SEPTEMBER 20, 2014 9:58 AM

http://dotearth.blogs.nytimes.com/2014/09/20/on-the-path-past-9-billion-little-crosstalk-between-u-n-sessions-on-population-and-global-warming/?partner=rss&emc=rss

Dano said...

:o)



Best,

D