Big reason for the jump in sea level rise – Ice sheets moving faster today than anyone thought possible a decade ago.
“People have gone as far as throwing rubber ducks down the holes to see where the rubber ducks come out,” said Tom Wagner, cryosphere program manager for NASA, which funded the research. “And no one has ever found a rubber duck.”
Some water may linger in recently discovered aquifers inside the ice, one of which is estimated to be the size of West Virginia.
Regardless, a significant fraction is not coming out right away, the study found. During the peak of the rare melt event, the atmosphere-based model overpredicted the flow to the sea by a few fractions of a cubic kilometer a day. Nonetheless, by late summer, the model and actual outflow were about in sync, Smith said.
So, the model gets big melt events wrong, even if it is close to capturing the flow in the longer run.
“That water isn’t just going to stay; it’s going to start coming out eventually,” Smith said. “It might have come out 18 months later. I can’t envision the ice sheet absorbing that water for centuries.”
The planet’s two largest ice sheets – in Greenland and Antarctica – are now being depleted at an astonishing rate of 120 cubic miles each year. That is the discovery made by scientists using data from CryoSat-2, the European probe that has been measuring the thickness of Earth’s ice sheets and glaciers since it was launched by the European Space Agency in 2010.
Even more alarming, the rate of loss of ice from the two regions has more than doubled since 2009, revealing the dramatic impact that climate change is beginning to have on our world.
The researchers, based at Germany’s Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research – used 200m data points across Antarctica and 14.3m across Greenland, all collected by CryoSat, to study how the ice sheets there had changed over the past three years. The satellite carries a high-precision altimeter, which sends out short radar pulses that bounce off the ice surface and then back to the satellite. By measuring the time this takes, the height of the ice beneath the spacecraft can be calculated.
It was found from the average drops in elevation that were detected by CryoSat that Greenland alone is losing about 90 cubic miles a year, while in Antarctica the annual volume loss is about 30 cubic miles. These rates of loss – described as “incredible” by one researcher – are the highest observed since altimetry satellite records began about 20 years ago, and they mean that the ice sheets’ annual contribution to sea-level rise has doubled since 2009, say the researchers whose work was published in the journal Cryosphere last week.
30 cubic miles of ice loss per year in Antarctica
7,200,000 cubic miles of ice in Antarctica
= 240,000 years until Antarctica melted at current rate
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
90 cubic miles of ice loss per year in Greenland
684,000 cubic miles of ice in Greenland
= 7600 years until Greenland melted at current rate
Looks like sea level could be rising for a very long time.
Current rate… Try the math with an exponential growth of rate. That would be more realistic. Problem is we don’t know much yet about the rate growth. (Take 10-20y doubling time of if you don’t find any number).
total losses have doubled in the last 5 years.
Dr Jason Box estimates a 7 – 10 year doubling time.
If 5 years is the case, James Hansen has written, we can look for a meter of sea level rise before 2050. More like 5 meters by century’s end.
My money is on Hansen. Boy, I wish I could be around to see if he is right.
Me too. I have the advantage(?) of coming from a family that tends to live to 90+ so I could well live beyond 2040.
I’m not so sure that I’d want my last few years to be filled with dread and/or with my family sighing and harrumphing in response to my cantankerous announcements of “I told you so”.
Yeah, adelady. At least, for those younger who accept the science now there will be no bad awakening. To see one’s world view disintegrate at old age, facing one’s death in an alien world, is perhaps the worst I wish to some deniers. My advice to them: The longer you stick your head in the sand, the worse your arse will burn later.
Yes, but that is math that is beyond my capabilities.
We are in a geologic ice age, by definition, since the poles are frozen. Why should we want to stay in an ice age? Life is more abundant when it is warm then when it is cold.
That’s a paragraph which is more wrong than fractally wrong… it’s, I don’t know… quantum wrong, organically wrong, multilaterally symmetrically wrong in eleven dimensions.
Somebody is going to go upside your head on that one.