US: Twenty years of satellite radar imagery of the northern Alaskan region show how changes in the climate are affecting high-latitude environments and how the lakes are on decline during winters. Changes in air temperature and winter precipitation over the last five decades have affected the timing, duration and thickness of the ice cover on lakes in the Arctic.
In a recent study of Alaska’s North Slope, the ice regimes of shallow lakes were documented using radar images from ESA’s ERS-1 and -2 satellites. The study reveals a 22% decrease of ‘grounded ice’ – or ice frozen through to the lakebed – from 1991 to 2011. This is equivalent to an overall thinning of ice by 21–38 cm. “Prior to starting our analysis, we were expecting to find a decline in ice thickness and grounded ice based on our examination of temperature and precipitation records of the past five decades from the Barrow meteorological station. At the end of the analysis, when looking at trend analysis results, we were stunned to observe such a dramatic ice decline during a period of only 20 years,” said Cristina Surdu, lead author of the study.