August 20, 2015

Disastrous Year for North Cascade Glacier Mass Balance (Snow/Ice Economy)

Posted by Mauri Pelto


Mass loss of North Cascade glaciers visualized.

A disastrous year is unfolding in 2015 for North Cascade glaciers, if normal melt conditions continue the range will lose 5-7% of its entire glacier volume in one year! For the 32nd consecutive year we were in the North Cascade Range, of Washington to observe the mass balance of glaciers across the entire mountain range. The melt season is not over, but already the mass loss is greater than any other year, with six weeks of melting left. An alpine glacier’s income is the snow that accumulates, and to be have an equilibrium balance sheet for a year, alpine glaciers typically need 50-65% snowcovered surfaces at the end of the melt season.  Below the accumulation zone, net assets are lost via ablation.

In 2015 of the 9 glaciers we examined in detail, 6 had less than 2% retained snowcover, which will be gone by the end of August.  Two more had no 2015 snowpack greater than 1.7 m in depth, which will also melt away before summer ends.  Average ablation during the August field season was 7 cm per day of snow, and 7.5 cm of ice. Only one glacier will have any retained snowcover at the end of the summer, we will be checking just how much in late September. This is the equivalent of a business having no net income for a year, but continuing to have to pay all of its bills. Of course that comes on top of more than 27 years of consecutive mass balance loss for the entire “industry” of global alpine glaciers.  The business model of alpine glaciers is not working and until the climate they run their “businesses” in changes, alpine glaciers have an unsustainable business model. Below this is illustrated glacier by glacier from this summer.  A following post will look at the glacier runoff aspect of this years field season.  The Seattle Times also featured our summer research.JillPeltoGMB_720_494_s_c1_c_c

Jill Pelto Painting of mass balance time series loss from 1984 to 2014. 

In a recent paper published in the Journal of Glaciology spearheaded by the WGMS group  (M. Zemp,  H. Frey, I.Gartner-Roer, S.Nussbaumer, M.Hoelzle, F.Paul, W.Haeberli and F.Denzinger), that I was co-author on, we examined the WGMS dataset on glacier front variations (~42 000 observations since 1600), along with glaciological and geodetic observations (~5200 since 1850).  The data set illustrated that “rates of early 21st-century mass loss are without precedent on a global scale, at least for the time period observed and probably also for recorded history.The rate of melting has been accelerating, and in the decade from 2001 to 2010, glaciers lost on average 75 centimetres of their thickness each year”, this is compared to the loss in the 1980’s and 1990’s 25 cm and 40 cm respectively each year (Pelto, 2015).  A comparison of the global and North Cascade Glacier mass balance records since 1980 indicate the cumulative loss, at bottom.


Columbia Glacier terminus August 3, 2015 with new expanding lake.


Upper portion of Columbia Glacier on Aug. 5, 2015 note lack of snowcover and all previous firn layers (firn is snow that survived a melt season but is not yet glacier ice).


Foss Glacier lacking snowcover and losing area fast this summer, this glacier will lose more than 15% of its volume in 2015.


Measuring firn from 2011-2014 retained in a crevasse on Easton Glacier, 2015 snowpack lacking.


The typical end of summer snowline elevation on Easton Glacier, bare ice and firn in 2015.


Rainbow Glacier amidst the normal accumulation zone, where there should be 3-4 m of snowpack, none left.


Lynch Glacier view across the typical end of summer snow line region on Aug. 17th 2015.


Terminus of Lower Curtis Glacier with many annual layers exposed to rapid melt, 31 m of retreat from spring to August 11th, 2015.


ice worm firn

Only firn from 2013 and 2014 and bare ice at surface of Ice Worm Glacier.



Comparison of cumulative glacier mass balance in the North Cascades and Globally (WGMS)


Primary field team for the from left, Mauri Pelto (Nichols College), Jill Pelto (UMaine), Tyler Sullivan (UMaine), Ben Pelto (UNBC) and Erica Nied (U-Colorado) summer with contributions from Justin Wright, Tom Hammond, Oliver Grah and Jezra Beaulieu not pictured