The financial support of International Permafrost Association through the IPA Action is gratefully acknowledged for the 2016-2017 period. See http://ipa.arcticportal.org
The financial support of the Institut Pierre Simon Laplace is gratefully acknowledged for the 2014-2016 period. See www.ipsl.fr
The financial support of the French INSU/EC2CO program for the 2013-2014 period is gratefully acknowledged. See www.insu.cnrs.fr