North Cascade Glacier Mass Balance
NORTH CASCADE GLACIER CLIMATE PROJECT
Mauri S. Pelto, Director NCGCP
Nichols College, Dudley, MA 01571 mspelto@nichols.edu
North Cascades Glacier Mass Balance North American Glacier Mass Balance Glacier Mass Balance Prediction Glacier Mass Balance Forecasting Global Glacier Mass Balance Glacier Mass Balance Basics Updated 4/5/2013
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What is mass balance?
Crucial to the survival of a glacier is its mass balance, the difference between accumulation and ablation (melting and sublimation). Climate change may cause variations in both temperature and snowfall, causing changes in mass balance. Changes in mass balance control a glacier's long term behavior. It is the most sensitive climate indicator on a glacier.  A glacier with a sustained negative balance is out of equilibrium and will retreat. A glacier with a sustained positive balance is out of equilibrium and will advance.
What has research proven?  

We have measured the mass balance on ten glaciers in the North Cascades each year since 1984.  The cumulative mass loss has been substantial.  Annual mass balance is the most sensitive annual glacier climate indicator.  North Cascade glaciers annual balance has averaged -0.51 m/a of water equivalent from 1984-2010 a cumulative loss of over 13.25m in glacier thickness. This represents a net loss of ice thickness exceeding 14 m or  20-40 % of their total volume since 1984 due to negative mass balances. The trend in mass balance is becoming more negative which is fueling more glacier retreat and thinning note figure at right.  The map at right indicates the location of the glaciers (green circles) where we monitor annual glacier mass balance. 

The annual glacier mass balance record below indicates that the response of annual balance is quite similar for each glacier.  This demonstrates that it is regional climate changes from year to year that control glacier mass balance, not local microclimates.  The cause of the negative mass balances has primarily been temperature rise.  Precipitation has increased during the last 25 years.  However, snowpack has not indicating more winter rain and melt events. 

The data indicate broad regional continuity in glacial response to climate.  Cross correlation values of annual balance between glaciers ranged from 0.73 to 0.98.  The record reflects less variability and a more negative trend from 1984-1995.  Since 1996, there has been increasing inter-annual variability with alternately extreme positive and negative years, with a dominantly negative trend.  The annual balance of individual glacier is in a Table below The chart at right shows the annual balance of each glacier and how they are closely correlated, following the same trend from year to year, but do have a significant range in annual balance during each given year. 



 

Mass Balance loss on Mount Baker 1990-2010, 2012

The detailed reports are published at (Journal of Glaciology VOL. 42 No. 140 1996, Pelto: Annual net balance of North Cascade glaciers, 1984-94). and  2001; Spatial and Temporal Variations in Annual Balance of North Cascade Glaciers, Washington 1984-2000 Mauri S. Pelto and Jon Riedel. Hydrologic Processes 15, 3461-3472.

What are The Effects and Consequences?  The impact of negative mass balances is glaciers that are thinning, moving slower and in some case disappearing.  The cause of the mass balance loss is a decline in winter snowpack as noted on April 1 and a rise in ablation season temperature.

Annual ablation season temperature is rising and accumulated snowpack, April 1 SWE is declining.

 

Annual balance of 10 North Cascade Glaciers the first 10 monitored by the North Cascade Glacier Climate Project,

and  one South Cascade by the USGS.

Glacier Columbia Daniels Easton Foss Ice Worm L. Curtis Lynch Rainbow Sholes Yawning S. Cascade Mean
Year NCGCP NCGCP NCGCP NCGCP NCGCP NCGCP NCGCP NCGCP NCGCP NCGCP USGS ba
1984 0.21 0.11   0.51 0.86 0.39 0.33 0.58   0.09 0.12 0.39
1985 -0.31 -0.51   -0.69 -0.75 -0.16 -0.22 0.04   -0.23 -1.20 -0.35
1986 -0.20 -0.36   0.12 -0.45 -0.22 -0.07 0.20   -0.10 -0.61 -0.14
1987 -0.63 -0.87   -0.38 -1.39 -0.56 -0.30 -0.26   -0.47 -2.06 -0.61
1988 0.14 -0.15   0.23 -0.24 -0.06 0.17 0.43   -0.06 -1.34 0.06
1989 -0.09 -0.37   0.09 -0.67 -0.29 0.03 -0.24   -0.19 -0.91 -0.22
1990 -0.06 -0.68 -0.58 -0.27 -0.92 -0.51 -0.12 -0.46 -0.32 -0.32 -0.11 -0.42
1991 0.38 -0.07 0.41 0.30 0.63 0.04 0.36 0.44 0.48 0.23 0.07 0.32
1992 -1.85 -1.70 -1.67 -1.92 -2.23 -1.76 -1.38 -1.65 -1.88 -2.06 -2.01 -1.81
1993 -0.90 -0.83 -1.01 -0.73 -1.02 -0.48 -0.62 -0.80 -0.96 -0.66 -1.23 -0.80
1994 -0.96 -0.45 -0.92 -0.68 -1.23 -0.55 -0.40 -0.72 -0.88 -0.62 -1.60 -0.74
1995 -0.45 0.24 -0.31 0.31 0.47 -0.21 0.18 -0.20 -0.25 -0.26 -0.69 -0.05
1996 -0.62 0.45 0.22 0.34 0.57 -0.18 0.53 0.12 0.06 0.34 0.10 0.18
1997 0.35 0.88 0.53 0.50 0.76 0.27 0.62 0.51 0.42 0.50 0.63 0.53
1998 -1.46 -1.82 -1.87 -1.95 -1.64 -1.38 -1.97 -1.49 -1.56 -2.03 -1.60 -1.72
1999 1.75 1.52 1.61 1.56 2.15 1.55 1.45 1.84 1.76 1.63 1.02 1.68
2000 0.40 -0.25 -0.10 -0.10 -0.33 -0.25 -0.24 0.15 -0.08 -0.18 0.38 -0.10
2001 -1.52 -1.75 -1.93 -1.92 -2.15 -1.88 -1.82 -1.71 -1.83 -1.94 -1.57 -1.85
2002 0.60 -0.18 0.18 0.10 0.05 0.13 -0.13 0.12 0.21 0.26 0.55 0.13
2003 -1.17 -1.52 -0.98 -1.35 -1.40 -1.25 -1.20 -0.98 -1.12 -1.85 -2.10 -1.28
2004 -1.83 -2.13 -1.06 -1.94 -2.00 -1.51 -1.98 -1.67 -1.86 -1.78 -1.65 -1.78
2005 -3.21 -2.90 -2.45 -3.12 -2.85 -2.75 -2.62 -2.65 -2.84 -3.02 -2.45 -2.84
2006 -0.98 -1.25 -0.79 -1.02 -1.35 -1.06 -1.05 -0.61 -0.71 -0.93 -1.45 -0.98
2007 -0.37 0.12 0.26 -0.38 -0.62 -0.40 0.07 0.20 0.29 -0.13 -0.21 -0.10
2008 0.96 0.41 0.45 0.18 -0.10 0.12 0.51 0.65 0.20 0.48 -0.30 0.39
2009 -0.90 -1.35 -2.06 -2.02 -1.56 -2.15 -1.82 -1.98 -2.68 -1.62 -2 -1.81
2010 -0.21 -0.26 0.68 -0.11 -0.38 -0.44 -0.34 0.76 0.17 0.94    
Cumulative -12.72 -15.41 -12.07 -14.23 -17.41 -15.11 -11.69 -10.14 -13.55 -14.92 -19.92 -12.47
Mean -0.49 -0.59 -0.60 -0.55 -0.67 -0.58 -0.45 -0.39 -0.68 -0.57 -0.81  

 

Col

Dan

Foss

IW

LC

Lyn

Rain

Yawn

East

SC

Columbia

1

                 

Daniels

0.85

1

               

Foss

0.9

0.95

1

             

Ice Worm

0.86

0.95

0.93

1

           

Lower Curtis

0.93

0.93

0.95

0.93

1

         

Lynch

0.86

0.96

0.98

0.91

0.94

1

       

Rainbow

0.94

0.92

0.95

0.92

0.97

0.94

1

     

Yawning

0.92

0.95

0.97

0.9

0.97

0.97

0.95

1

   

Easton

0.93

0.98

0.98

0.97

0.97

0.97

0.99

0.99

1

 

South Cascade

0.83

0.97

0.78

0.84

0.78

0.75

0.76

0.81

0.94

1

Table 3 Cross Correlation of annual balance on North Cascade glaciers 1984-2005.