Recent temperature change on the Juneau Icefield, Alaska.

As one of the largest icefields in the world, the recent mass loss from the Juneau Icefield (JIF) in Southeast Alaska will transform the local environment, hydrologic system, and will contribute to global sea level rise. To better understand the climatic context of these changes, our study aims to characterize recent changes in the surface temperature of the JIF. We combine decades-long temperature records from stations across the Icefield, produced and maintained by the Juneau Icefield Research Program, with reanalysis products, to examine trends in the annual mean and seasonal surface temperatures over the last 50 years. We find coherent multi-annual variability and trends between the stations across the ice-field and with the regional estimates from reanalysis. Annual mean temperature on the Icefield has been increasing at about twice the rate of Earth's global average. Interestingly, trends in winter-time temperature on the Icefield are about double the annual average, while summer-time shows little trend oner the interval. There is some indication of elevation-dependence in these trends. These results have implications for the source of recently documented negative anomalies in the glacier mass balance of the icefield. We investigate possible sources of the seasonal and elevation dependence of these warming trends.