Canada's Queen Elizabeth Islands contain ∼14% of Earth's glacier and ice cap area. Snow accumulation on these glaciers is low and varies little from year to year. Changes in their surface mass balance are driven largely by changes in summer air temperatures, surface melting and runoff. Relative to 2000–2004, strong summer warming since 2005 (1.1 to 1.6°C at 700 hPa) has increased summer mean ice surface temperatures and melt season length on the major ice caps in this region by 0.8 to 2.2°C and 4.7 to 11.9 d respectively. 30–48% of the total mass lost from 4 monitored glaciers since 1963 has occurred since 2005. The mean rate of mass loss from these 4 glaciers between 2005 and 2009 (−493 kg m−2 a−1) was nearly 5 times greater than the 1963–2004 average. In 2007 and 2008, it was 7 times greater (−698 kg m−2 a−1). These changes are associated with a summer atmospheric circulation configuration that favors strong heat advection into the Queen Elizabeth Islands from the northwest Atlantic, where sea surface temperatures have been anomalously high.

ABSTRACT. This study presents the first reanalysis of a long-term glacier mass-balance record in the Canadian Arctic. The reanalysis is accomplished through comparison of the 1960-2014 glaciological mass-balance record of White Glacier, Axel Heiberg Island, Nunavut, with a geodetically derived mass change over the same period. The corrections applied to homogenize the two datasets, including adjusting for changes in hypsometry over the period of record and the generic differences between methods, are discussed along with the associated systematic and random errors of the two forms of mass-balance measurement. Statistical comparison of the two datasets reveals that within the error margin there is no significant difference between the average annual glaciological balance (-213 ± 28 mm w.e. a ) and geodetic balance (-178 ± 16 mm w.e. a −1 ) at White Glacier over the 54 year record. The validity of this result, and the assumptions made in implementing the glaciological method, are critically assessed.

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White Glacier is a valley glacier at 79.5°N with an area of 38.7 km2. Its mass balance has been measured, over 32 years with a 3 year gap, by standard techniques using the stratigraphic system with a stake density of the order of one stake per km2. Errors in stake mass balance are about ±(200–250) mm, due largely to the local unrepresentativeness of measurements. Errors in the whole-glacier mass balanceBare of the same order as single-slake errors. However, the lag-1 autocorrelation in the time series ofBis effectively zero, so it consists of independent random samples, and the error in the long-term “balance normal”〈B〉is noticeably less.〈B〉is −100 ± 48 mm. The equilibrium-line altitude (ELA) averages 970 m. with a range of 470–1400 m. Mass balance is well correlated with ELA, but detailed modelling shows that the equilibrium line is undetectable on visible-band satellite images. A reduced network of a few stakes could give acceptable but less accurate estimates of the mass balance, as could estimates based on data from a weather station 120 km away. There is no evidence of a trend in the mass balance of White Glacier. To detect a climatologically plausible trend will require a ten-fold reduction of measurement error, a conclusion which may well apply to most estimates of mass balance based on similar stake densities.

ABSTRACT. While Glacier is a ya lley glac ier a t 79.5° N with a n area of 38.7 km 2 .Its m ass bala nce ha s b ee n meas ured , oyer 32 years with a 3 yea r gap, b y stand a rd tec hniques using th e slra ti g ra phi c sy ·te m wi th a stake den si l)' of th e order of onc sla ke p CI' km 2 . Errors in stak e m ass bala nce are abo ut ± (200-250 ) mm , du e larg ely to the local un represe n ta ti\'el1ess of measuremen ts. Errors in th e whole-gla cier mass balan ce B arc of the same order as sin gle-sla k e errors. Howeve r, the lag-I autocorrelation in th e time seri es of B is efTec tiyel y zero, so it consists of ind epende nt ra nd om sa mpl es, a nd th e error in the lo ng-term "bala nce norm a l" (B ) is noticeably less. (B ) is -lOO ± 48 mm. The equilibrium-lin e altitude (ELA ) ave rages 970m, with a range of 470-1400 m . M ass bal a nce is well correlated with ELA, but d etailed mod e lling shows th a t th e equilibrium line is und etec ta ble o n \'isible-b a nd sa tellit e images . A reduced ne two rk of a fe\\' sta kes cou ld gi\'e accep ta bl e but less accurate es tim a tes of th e mass ba lance, as cou ld estim ates based o n data from a \\'eat h e r stati on 120 km away . Th ere is no evid ence of a tre nd in th e m ass ba la nce o f \ \'hite Glacier. To d etect a c1im ato logi call y plausible trend will require a ten-fold reduc tion of meas ure ment error, a concl usion which m ay well a ppl y to most es timates of mass bala nce based on simil ar sta ke d ensiti es .