Guest essay by JohnA
Yes, it’s been a while because frankly, it’s difficult for me to keep following eco-Armageddon when I keep falling asleep or doing other stuff like living and working.
But then this popped up:
This leads to the original paper with the catchy title “Geodetic measurements reveal similarities between post–Last Glacial Maximum and present-day mass loss from the Greenland ice sheet” by Khan et al
The abstract goes (stay awake at the back!) like this
Accurate quantification of the millennial-scale mass balance of the Greenland ice sheet (GrIS) and its contribution to global sea-level rise remain challenging because of sparse in situ observations in key regions. Glacial isostatic adjustment (GIA) is the ongoing response of the solid Earth to ice and ocean load changes occurring since the Last Glacial Maximum (LGM; ~21 thousand years ago) and may be used to constrain the GrIS deglaciation history. We use data from the Greenland Global Positioning System network to directly measure GIA and estimate basin-wide mass changes since the LGM. Unpredicted, large GIA uplift rates of +12 mm/year are found in southeast Greenland. These rates are due to low upper mantle viscosity in the region, from when Greenland passed over the Iceland hot spot about 40 million years ago. This region of concentrated soft rheology has a profound influence on reconstructing the deglaciation history of Greenland. We reevaluate the evolution of the GrIS since LGM and obtain a loss of 1.5-m sea-level equivalent from the northwest and southeast. These same sectors are dominating modern mass loss. We suggest that the present destabilization of these marine-based sectors may increase sea level for centuries to come. Our new deglaciation history and GIA uplift estimates suggest that studies that use the Gravity Recovery and Climate Experiment satellite mission to infer present-day changes in the GrIS may have erroneously corrected for GIA and underestimated the mass loss by about 20 gigatons/year.
Now the paper is quite detailed as to how they take the measurements of an ice sheet that is three times the area of Texas and contains good stuff about isostatic rebound due to ice mass loss and how they calibrate the gravity measurements taken by the GRACE satellites to measurements taken all around Greenland.
Actually in the middle of this, they make an admission that nobody notices (because no-one reads these things)
Say what? That a large amount of increased flow comes from natural tectonic processes? What exactly can we do about that? Tax it?
And bad news for climate models
We demonstrate the importance of correctly accounting for GIA when using Gravity Recovery and Climate Experiment (GRACE) satellite data, because a proportion of the mass gain in central Greenland reported in several recent studies [for example, Sutterley et al. (32)] using GRACE and predicted by models in a warming climate (33) could be an artifact of an erroneous GIA correction in the interior.
So it’s worse because the apparent ice gain in the center may be due to how quickly Greenland rebounds to lessening ice thickness. Oh, and the models are therefore incorrectly calibrated and wrong.
But here’s the money quote that found its way into distinguished scientific journals such as the New York Post (shown as a percentage)
As a consequence, studies will underestimate ice mass loss inferred from GRACE observations by 19 Gt/year when using ICE-5G as a GIA correction.
But 19 Gigatonnes per year more than what?
From the New York Post we get this:
The already unstable ice sheet in Greenland is melting faster than previous research has showed, according to a new report.
The new study, published in Science Advances, discovered that the island is losing 550 trillion pounds of ice a year — 40 trillion, and about 7.6 percent, more than scientists previously thought.
The number is equivalent to losing the weight of 50,000 Empire State Buildings, according to the Associated Press.
At last, Real numbers! 550 trillion pounds per year is lost from Greenland, an increase of 40 trillion from previous estimates! 50,000 Empire State buildings! That must be a lot of water, mustn’t it?
But it’s in pounds not kilograms so let’s convert to sensible units
550 trillion pounds is 5.5 x 10^14 * 0.453592 = 2.49 x 10^14 kg
So approximately 250 gigatons (1 GT =10^12 kg) per year
That mass of ice turns into water in the Earth’s oceans and occupies a volume of
2.49 x 10^14/1000 = 2.49 x 10^11 cubic meters of water are added to global sea levels from Greenland.
How much would that raise sea levels?
The surface area of the world’s oceans is 361.9 million square kilometers. So making our units consistent that’s 361.9 x 10^6 x 10^6 = 3.619 x 10^14 square meters.
That means that the volume of water from Greenland every year would add an extra
2.49 x 10^11/(3.619 x 10^14) = 0.0006893 meters
which is 0.689 millimeters or 0.0271 inches to global sea levels every year.
That additional 40 trillion pounds actually added 0.045 mm/yr to global sea levels.
According to one co-author it’s scary
“It is pretty scary,” Michael Bevis, a professor at Ohio State University and co-author of the study, told the AP. “If you look at the last 15 years since we’ve been having these measurements, it’s clearly getting worse.”
Yes, it’s scary if you’re as easily scared as they clearly are at OSU.
By the way, your fingernails grow at around 3.5mm per month = 3.5 x 12 = 42 mm/year so your fingernails grow 42/0.693 = 60 times faster than the rise in sea-levels due to Greenland melting.
Will snails be in trouble?
Snails can travel up to 25 meters/day which is 25*365.24 = 8765 meters per year. which is 12 million times faster than the rise in sea level due to Greenland ice melt. Phew!
I would suggest running for the hills before you drown, but that would be cynical, wouldn’t it?
Back to sleep.