科學家警告，北半球的永凍土逐漸融化，將改變生態系統並對美國阿拉斯加、加拿大以及俄羅斯的道路與建築物造成損害。美國政府研究機構的科學家警告說，在2050年以前，很可能有半數以上的永凍土覆蓋區融化；而到了2100年，甚至會有九成以上永凍土融化與流失。
設立在波布爾德（Boulder）的美國「大氣研究國家中心」（National Center for Atmospheric Research，NCAR），以最新的氣候模型模擬變遷效應，結果顯示全球暖化可能融化地表的永凍土達厚度3公尺以上。
科學家預測，永凍土的融化，將使溢流至北極海的逕流增加，並且會釋放大量的二氧化碳至大氣層，進一步催化溫室氣體效應。
永凍土覆範圍約佔阿拉斯加85%的面積，最遠在安克拉治都可見到。科學家說，近期的暖化現象已使阿拉斯加中部大片區域的永凍土融解，由於土層中的冰融化，導致土塊崩解。這樣的結果是造成道路彎曲鼓起、房屋地基動搖、以及大片樹林「東倒西歪」的狀況。
在西伯利亞，據報一些工業設備以因此遭到嚴重損害。未來若永凍土進一步流失，將可能威脅到遷移性動物，如馴鹿以及北美馴鹿。
另一方面，科學家特別關切永凍土融化造成溫室氣體釋出的現象。永凍土所貯存的碳素，約佔所有土壤貯存量的30%，甚至更多；一但永凍土融解後，可能會導致大量的甲烷或二氧化碳釋出，其量之大甚至超過石化燃料所釋出的量。
此外，永凍土的融化經常引起大區域的林木傾倒，不僅殘害樹木，以永凍土為生存基礎的植被也受害。
Permafrost is losing its permanence across the Northern Hemisphere, altering ecosystems and damaging roads and buildings across Alaska, Canada, and Russia. Government scientists warned today that over half the area covered by this topmost layer of permafrost could thaw by 2050 and as much as 90 percent by 2100.
New climate simulations from the National Center for Atmospheric Research (NCAR) in Boulder show that global warming may melt the top 10 feet (3 meters) or more of the frozen soil.
The scientists predict the thawing permafrost will increase runoff to the Arctic Ocean and release vast amounts of carbon dixoide into the atmosphere, increasing the greenhouse effect.
Permafrost occurs under about 85 percent of Alaska's surface area, and patches of permafrost can be found as far south as Anchorage. Recent warming has degraded large sections of permafrost across central Alaska, with pockets of soil collapsing as the ice within it melts. The results include buckled highways, destabilized houses, and "drunken forests," trees that lean at wild angles, the authors say.
In Siberia, some industrial facilities have reported significant damage. Further loss of permafrost could threaten migration patterns of animals such as reindeer and caribou.
The new study highlights concern about emissions of greenhouse gases from thawing soils. Permafrost may hold 30 percent or more of all the carbon stored in soils worldwide. As the permafrost thaws, it could lead to large-scale emissions of methane or carbon dioxide beyond those produced by fossil fuels.
In addition, thawing permafrost often causes large sections of forest to collapse, killing trees and other vegetation that live on a foundation of permafrost.
