Temperatures in the planet’s most northerly regions have been rising four times faster than the global average. A new dataset could hold the key to explaining this worrying phenomenon.
Utilising GPS satellite radiometers, a team from Sandia National Laboratories has been capturing information on the sunlight bouncing off the Arctic landscape, a reflective process known as albedo.
Previous studies have shown ‘amplification’ of global heating in the Arctic could be connected to the reflectivity of sea-ice, and it now appears clear the overall reduction in cover means more ‘dark ocean’ is exposed to warm rays. As such, far more sunlight is absorbed compared to snow-covered ice, rapidly raising temperatures. In addition, the remaining sea-ice, including ponding water on ice due to melting, is producing less albedo, so more heat from the sun stays at lower levels, further contributing to heating.
‘The uneven warming in the Arctic is both a scientific curiosity and a pressing concern, leading us to question why this landscape has been changing so dramatically,’ said Erika Roesler, an atmospheric and climate scientist at Sandia. ‘New observational climate datasets are unique. To qualify as a climate dataset, observations must span a multitude of years. Small-scale science projects are typically not that long in duration, making this dataset particularly valuable.’
‘There have been numerous local measurements and theoretical discussions regarding the effects of water puddling on ice albedo,’ added Amy Kaczmarowski, an engineer at Sandia. ‘This study represents one of the first comprehensive examinations of year-to-year effects in the Arctic region. Sandia’s data analysis revealed a 20% to 35% decrease in total reflectivity over the Arctic summer. According to microwave sea-ice extent measurements collected during the same period, one-third of this loss of reflectivity is attributed to fully melted ice.’
This suggests that as more Arctic sea-ice disappears the heating in the region will accelerate, and the remaining two-thirds of reflectivity loss is caused by ice weathering. But it is now vital to understand how much weathering affects sea-ice, and reflectivity. Kaczmarowski was responsible for conducting analysis of a data set spanning 2014 to 2019. The GPS technology will continue to provide readings until 2040, with regular updates set to be shared with industry by Sandia, in a bid to encourage other investigation, more research and development relevant to Arctic climate studies and modelling.
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Image: Sandia National Laboratories