Ice Waves — The most fantastic climate science of last week (that crossed my desk):
This work evaluates a new discovery of melt waves of increased ice and water discharge in the Greenland melt years of 2010 and 2012. At one glacier (Rinks,) the peak monthly increased ice and water discharge was about equal to 0.5% of total net Greenland ice and water loss. The Rinks accounts for about 2 percent of total Greenland ice loss.
An underice river of melt emerges from the Greenland Ice Cap at a place called Point 660 near Kangerlussuaq, on the west coast near the Arctic Circle.
The ice loss peaked after summer the heat waves in the fall at 1.67 Gigatons (Gt) per month and extended into deep winter. In 2012, t he total excess loss, above the normal loss for the Rinks, was 6.7 Gt where the Rinks normally loses 1 to 2 Gt per year. Evidence of the increased flow from 2012 extended through the winter and into the summer of 2013.
These waves of ice were caused by increased meltwater penetrating the ice sheet to bedrock through crevasses and moulins (ice sheet drains) that can extend thousands of feet deep into the two-mile high ice sheet. Where the drainage meets bedrock, parts of the ice sheet literally float (water is heavier than ice,) decreasing friction and increasing flow.
The way these melt waves were discovered is through gravitational changes measured by the GRACE satellites.
Greenland ice loss and melt increased over 500 percent from 2002 to 2011 as per the 2013 IPCC.
This ice wave work was done by researchers at the Jet Propulsion Laboratory, California Institute of Technology.
Adhikari et al., Mass transport waves amplified by intense Greenland melt and detected in solid Earth deformation, GEophhysical Resaerch Letters, May 15, 2017.pdf
http://onlinelibrary.wiley.com/doi/10.1002/2017GL073478/epdf
Greenland Glacier Discharge Ranking:
Rignot, et al., Changes in the velocity structure of the Greenland Ice Sheet, Science, February 17, 2006.
ftp://soest.hawaii.edu/coastal/Climate%20Articles/Rignot%20and%20Kanagaratnam%202006.pdf
IPCC: Ice loss increased 532 percent since 2001… “The rate of ice loss from the Greenland ice sheet has very likely substantially increased from 34 [–6 to 74] Gt yr–1 over the period 1992 to 2001 to 215 [157 to 274] Gt yr–1 over the period 2002 to 2011.” This is a ten-year average. 2013 IPCC, summary for Policy Makers, B3 Cryshpere, Bullet 2, page 9.
https://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_SPM_FINAL.pdf