The Arctic’s frozen ground contains large stores of organic carbon that have been locked in the permafrost for thousands of years. As global temperatures rise, that permafrost is starting to melt, raising concerns about the impact on the climate as organic carbon becomes exposed. A new study is shedding light on what that could mean for the future by providing the first direct physical evidence of a massive release of carbon from permafrost during a warming spike at the end of the last ice age.The study, published this week in the journal Nature Communications, documents how Siberian soil once locked in permafrost was carried into the Arctic Ocean during that period at a rate about seven times higher than today.