Up here in Alaska, and I speculate also in Siberia, you can have a thin layer of melted earth in the spring, and flowers blooming in just a week or so of sunshine. But underneath you have permafrost.
However there are sink holes with water running underneath, and iced over lakes/rivers that look walk-able. Walk out, fall in, and freeze next to or under the permafrost.
But that's in spring. Wouldn't the coming warming, albeit a short warm season, allow predation and deterioration?