The annual river ice cover will decline by about six days for every one degree Celsius increase in global temperatures, posing economic and environmental consequences, according to a study. The research, published in the journal Nature, is the first to look at the future of river ice on a global scale. "We used more than 400,000 satellite images taken over 34 years to measure which rivers seasonally freeze over worldwide, which is about 56 per cent of all large rivers," said Xiao Yang, a postdoctoral scholar at the University of North Carolina at Chapel Hill (UNC-Chapel) in the US.
"We detected widespread declines in monthly river ice coverage. And the predicted trend of future ice loss is likely to lead to economic challenges for people and industries along these rivers, and shifting seasonal patterns in greenhouse gas emissions from the ice-affected rivers," Yang said in a statement.
The team also looked at changes to river ice cover in the past, and modelled predicted changes for the future.
Comparing river ice cover from 2008-2018 and 1984-1994, the team found a monthly global decline ranging from 0.3 to 4.3 percentage points.
The greatest declines were found in the Tibetan Plateau, eastern Europe, and Alaska.
"The observed decline in river ice is likely to continue with predicted global warming," the researchers found.
For the future, the team compared expected river ice cover through 2009-2029 and 2080-2100.
Findings showed monthly declines in the Northern Hemisphere ranging from 9-15 per cent in the winter months, and 12-68 per cent during the spring and fall.
The Rocky Mountains, northeastern US, eastern Europe, and Tibetan Plateau are expected to take the heaviest impact, the researchers said.
"Ultimately, what this study shows is the power of combining massive amounts of satellite imagery with climate models to help better project how our planet will change," said UNC-Chapel Hill Associate Professor Tamlin Pavelsky.