What has research proven?
Annual balance is the most sensitive annual glacier climate indicator. North Cascade glaciers annual balance has averaged -0.54 m/a of water equivalent from 1984-2006, a cumulative loss of over 12.4 m 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.
Annual longitudinal profiles on
nine glaciers North Cascade glaciers confirm this volume change indicating a
loss of
-10.7 to -15.3 m in thickness (-9.6 to -13.8 m w.e) between 1984 and 2006,
agreeing well with the cumulative mean annual balance of
-12.4 m w.e for that
period. 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.
