Editing Permafrost (section)

=== Increasing active layer thickness ===
Globally, permafrost warmed by about {{cvt|0.3|C-change}} between 2007 and 2016, with stronger warming observed in the continuous permafrost zone relative to the discontinuous zone. Observed warming was up to {{convert|3|C-change|F-change}} in parts of [[Northern Alaska]] (early 1980s to mid-2000s) and up to {{convert|2|C-change|F-change}} in parts of the Russian European North (1970–2020). This warming inevitably causes permafrost to thaw: [[active layer]] thickness has increased in the European and [[Russian Arctic]] across the 21st century and at high elevation areas in Europe and Asia since the 1990s.<ref name="AR6_WG1_Chapter922">Fox-Kemper, B., H. T. Hewitt, C. Xiao, G. Aðalgeirsdóttir, S. S. Drijfhout, T. L. Edwards, N. R. Golledge, M. Hemer, R. E. Kopp, G.&nbsp; Krinner, A. Mix, D. Notz, S. Nowicki, I. S. Nurhati, L. Ruiz, J.-B. Sallée, A. B. A. Slangen, and Y. Yu, 2021: [https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Chapter09.pdf Chapter 9: Ocean, Cryosphere and Sea Level Change]. In [https://www.ipcc.ch/report/ar6/wg1/ ''Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change''.] [Masson-Delmotte, V., P. Zhai, A. Pirani, S. L.&nbsp; Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M. I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J. B. R. Matthews, T. K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 1211–1362, doi:10.1017/9781009157896.011.</ref>{{rp|1237}}

Between 2000 and 2018, the average active layer thickness had increased from ~{{convert|127|cm|ft}} to ~{{convert|145|cm|ft}}, at an average annual rate of ~{{convert|0.65|cm|in}}.<ref name="Li2022" />

In [[Yukon]], the zone of continuous permafrost might have moved {{convert|100|km}} poleward since 1899, but accurate records only go back 30 years. The extent of subsea permafrost is decreasing as well; as of 2019, ~97% of permafrost under Arctic ice shelves is becoming warmer and thinner.<ref>{{Cite journal |last1=Overduin |first1=P. P. |last2=Schneider von Deimling |first2=T. |last3=Miesner |first3=F. |last4=Grigoriev |first4=M. N. |last5=Ruppel |first5=C. |last6=Vasiliev |first6=A. |last7=Lantuit |first7=H. |last8=Juhls |first8=B. |last9=Westermann |first9=S. |date=17 April 2019 |title=Submarine Permafrost Map in the Arctic Modeled Using 1-D Transient Heat Flux (SuPerMAP) |journal=Journal of Geophysical Research: Oceans |volume=124 |issue=6 |pages=3490–3507 |doi=10.1029/2018JC014675 |bibcode=2019JGRC..124.3490O |hdl=1912/24566 |s2cid=146331663 |url=https://epic.awi.de/id/eprint/49740/1/Overduin_etal2019_ePIC.pdf }}</ref><ref name="AR6_WG1_Chapter92" />{{rp|1281}}

Based on high agreement across model projections, fundamental process understanding, and paleoclimate evidence, it is virtually certain that permafrost extent and volume will continue to shrink as the global climate warms, with the extent of the losses determined by the magnitude of warming.<ref name="AR6_WG1_Chapter922" />{{rp|1283}}

Permafrost thaw is associated with a wide range of issues, and [[International Permafrost Association]] (IPA) exists to help address them. It convenes International Permafrost Conferences and maintains [[Global Terrestrial Network for Permafrost]], which undertakes special projects such as preparing databases, maps, bibliographies, and glossaries, and coordinates international field programmes and networks.<ref>{{cite web|author= |url=https://www.permafrost.org/frozen-ground-newsletter/ |title=Frozen Ground, the News Bulletin of the IPA |language= |website=International Permafrost Association |date= 2014-02-10|accessdate=2016-04-28}}</ref>