Arctic ice grew by a third in 2013 despite the continued rise of global temperatures driven by climate change, researchers report. A cool summer in the region that year may have driven this increase in ice volume, suggesting variations in temperatures during the warmest months could have a larger than expected impact on total ice deposits.
Despite the short-term gain seen in Arctic ice since 2013, researchers believe global warming will continue in the region, driving down ice volume over the coming decades. Over the last 30 years, the Arctic has warmed more than most other areas of the globe. Satellite images reveal the loss of 40 percent of the sea ice cover in the region over the last 35 years.
"We looked at various climate forcing factors, we looked at the snow loading, we looked at wind convergence and the melt season length of the previous summer. We found that the the highest correlation by far was with the melt season length — and over the summer of 2013, it was the coolest of the five years we have seen, and we believe that's why there was more multi-year ice left at the end of summer," said Rachel Tilling of University College London.
The Cyrosat satellite has spent five years collecting data on the depth of sea ice in the Arctic. This measure is carefully tracked by climatologists and biologists seeking to understand the way climate change, including global warming, is affecting the region. Between the years 2010 and 2012, sea ice deposits fell by 14 percent, according to investigators. The following year, levels rose by 33 percent, followed by an additional 25 percent increase in 2014.
"Until CryoSat-2 was launched, it was tricky to measure the volume of Arctic sea ice as the pack drifts and measurements could not be taken across the whole region. Together with maps of sea ice extent, our measurements of sea ice thickness now complete the picture because they reveal what's going on below the water, where most of the action happens," Tilling said.
A cool summer in 2013 would have provided fewer days than normal when temperatures were above freezing. This would result in the loss of smaller-than-normal rates of ice melt. The next winter, snows would have a higher-than-normal base on which to pile more frozen precipitation.
Over the coming decades, climatologists will continue to monitor changes in sea ice levels around the Arctic.
Analysis of sea ice in the Arctic region was profiled in the journal Nature Geoscience.
Photo: NASA Goddaddrd Space Flight Center | Flickr
