Degrading Permafrost Peat Mound (IMAGE) Proceedings of the National Academy of Sciences Caption Degrading permafrost peat mound (palsa), Tavvavuoma, Sweden. Credit Image credit: Gustaf Hugelius. Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.