The non-synchronous response of Rabots Glaciär and Storglaciären, northern Sweden, to recent climate change: a comparative study

Rabots Glaciär and Storglaciären, two small valley glaciers in the Swedish Arctic, have not behaved synchronously in response to recent climate change. Both glaciers advanced late in the 19th century and then began to retreat in response to a ~1˚C warming that occurred around 1910. By the mid-1980s the terminus and volume of Storglaciären had essentially stabilized, so it may have completed its response to the earlier warming. In contrast, ongoing thinning and retreat of Rabots Glaciär are substantial and suggest its response time is considerably longer. A time-dependent numerical model was used to investigate each glacier’s response to perturbations in mass balance. This modeling suggests that, for small perturbations, volume timescales for Storglaciären and Rabots Glaciär are ~125 and ~215 years, respectively. Another measure of response time (i.e. length response time) yields somewhat lower values for each glacier; however, what is significant is that by either measure and accounting for uncertainties, the response time for Rabots Glaciär is consistently about 1.5 times longer than that for Storglaciären. This implies that their non-synchronous behavior is likely due to differences in response times. The latter ultimately result from markedly different longitudinal geometries (particularly near the termini), velocity profiles and specific net balance gradients.