An automated method for tracking the calving margin positions of tidewater glaciers from MODIS imagery was developed, allowing for the recording of high temporal resolution change over 24 glaciers. Results compared well to those of other studies which have been limited in either temporal or spatial resolution by more labour intensive methods. Many glaciers exhibited a strong sensitivity to a seasonal forcing. Over 2002 to 2005, 14 of the glaciers retreated by over 0.5 km, the largest with a retreat of 5.0 km. Total recovery during 2005 to 2008 was 21% of previous retreat. During the study period both surrounding sea and air surface temperatures (SSTs and SATs) gradually increased by 2° and 1.5° C respectively until mid 2004, after which mean annual SAT dropped by 4° C and SSTs remained high, suggesting a dominant influence of SATs. Margin positions appeared to switch between stable bathymetric states, triggered by temperature changes. The rapid stepped retreats observed over short timescales indicate that future outlet glacier response to climate change is likely to be non-linear and that the findings of mass balance studies based upon comparisons between specific years may not be robust. Expanding this study over the whole ice sheet has been shown to be feasible and would depict margin changes in unprecedented spatio-temporal detail.