Mass balance of White Glacier, Axel Heiberg Island, N.W.T., Canada, 1960–91

White Glacier is a valley glacier at 79.5° N with an area of 38.7 km 2 . 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 km. Errors in stake mass balance are about ± (200-250) mm, due largely to the local unrepresentativeness of measurements. Errors in the whole-glacier mass balance B are of the same order as single-stake errors. However, the lag-l autocorrelation in the time series of B is effectively zero, so it consists of independent random samples, and the error in the long-term balance normal is noticeably less. 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.