According to new research published in environmental Research Letters, the Fukushima nuclear accident has put a unique stamp on snow and ice across the northern hemisphere.
The March 11, 2011, earthquake and tsunami off the northeast coast of Japan led to a month-long release of radioactive materials into the atmosphere, ocean and soil.
According to the report, experts collected ice and snow samples from some glaciers (2,000 kilometers across northwest China) in 2011 and 2018. By 2018, they expected the fukushima mark to have disappeared, but the freezing-thawing process unexpectedly concentrated it, creating a strong and persistent reference layer in the ice.
Many reference layers over the past 50 years, such as the Chernobyl nuclear disaster, disappeared during recent warming events, making it difficult for scientists to date the upper layers of the ice core, the report said. “The reference layer is crucial and a prerequisite for telling the ice core story,” said one of the study’s co-authors. “In a decade or two, when the snow turns to ice, the Fukushima layer will be useful for dating the ice,” he added.