The study reveals that the region once experienced long stretches without permafrost. The discovery shows how quickly this icy world can react when temperatures rise.<\/p>\n \u201cThese deposits are like tiny time capsules,\u201d said study lead author Gina Moseley. \u201cThey show that northern Greenland<\/a> was once free of permafrost and much wetter than it is today.\u201d<\/p>\n Greenland was once warm<\/p>\n Cove Cave lies on Greenland\u2019s remote northern coast, accessible only by small aircraft and a long hike through untouched wilderness. <\/p>\n Inside, the team found calcite deposits formed by dripping water. Such minerals can\u2019t grow in frozen ground, so their presence means Greenland\u2019s Arctic once thawed deeply enough for liquid water to move underground.<\/p>\n The scientists dated these formations to between 9.5 and 5.3 million years ago. During this time, air temperatures were at least 55\u00b0F (13\u00b0C) higher than today, and carbon dioxide levels reached just above 310 parts per million.<\/p>\n Ocean surface temperatures were a few degrees warmer too. Greenland, which now lies buried in ice, once pulsed with moisture and warmth.<\/p>\n The Arctic cooled Greenland<\/p>\n The cave\u2019s story isn\u2019t one of endless summer. Between the warm phases came colder intervals when permafrost returned and water flow stopped.<\/p>\n Around 6.3 to 5.6 million years ago, glacial debris entered the cave system, marking brief periods when ice advanced across the landscape. <\/p>\n The minerals record these changes like pages in a diary \u2013 each layer showing a shift from frozen stillness to flowing warmth.<\/p>\n Ocean records from the same era show matching patterns. When sea temperatures<\/a> fell, the ground refroze. When the oceans warmed again, the cave revived. <\/p>\n The evidence links Greenland\u2019s land temperature to global ocean currents that shifted heat northward and southward.<\/p>\n \u201cFrom this we can see that the climate reacted strongly and rapidly to changing boundary conditions,\u201d said Moseley. <\/p>\n The Earth didn\u2019t need extreme carbon dioxide levels to melt Greenland. Even moderate increases were enough to reshape its environment.<\/p>\n Sunlight patterns shaped the Arctic<\/p>\n These ancient climate<\/a> swings followed predictable beats. The planet\u2019s tilt and orbit changed the sunlight reaching the poles. <\/p>\n During certain orbital alignments, sunlight strengthened, warming Greenland\u2019s soil and melting permafrost. At other times, weaker sunlight encouraged cold phases.<\/p>\n Between 9.6 and 9.3 million years ago, something strange happened \u2013 the Arctic warmed while Antarctica cooled. Later, both poles began moving in sync again.<\/p>\n The team suggests that vegetation played a part. When dense forests covered the Arctic, darker canopies absorbed more heat. As forests gave way to shrubs and tundra, the ground reflected sunlight and cooled faster.<\/p>\n This tug-of-war between land cover and light created a chain reaction. More warmth led to more evaporation and cloud cover, locking in moisture. More cooling turned the surface pale and reflective, driving ice formation. <\/p>\n The cave\u2019s oxygen isotope data trace these changes with striking detail, showing how easily the Arctic switched from thawed to frozen.<\/p>\n Chemistry of the Greenland cave<\/p>\n Inside Cove Cave, even the chemistry of the minerals tells a story. The team found sudden spikes in silicate concentrations after each cold spell.<\/p>\n These signals likely came from glacial erosion<\/a>, carried into the cave by meltwater as the ice retreated. Each chemical trace marked a moment when Greenland\u2019s surface shifted from ice to soil again.<\/p>\n The findings match computer models suggesting glaciers grew and shrank rapidly in northern Greenland during the Late Miocene. <\/p>\n The ice didn\u2019t stay for long \u2013 it advanced, melted, and reappeared in rhythm with Earth\u2019s orbit. The cave\u2019s record connects local changes in permafrost to global shifts in carbon dioxide and sea ice.<\/p>\n Lessons for Greenland and the Arctic<\/p>\n Moseley and her team point out something unsettling. The conditions that melted Greenland millions of years ago don\u2019t seem so different from today. <\/p>\n Back then, permafrost<\/a> vanished when carbon dioxide levels passed 310 ppm. Today, they\u2019re above 420 ppm.<\/p>\n \u201cThe Arctic has never been a stable system,\u201d said Moseley. \u201cIt shows how dynamic this region is and how quickly environmental conditions can change.\u201d<\/p>\n That same sensitivity makes today\u2019s Arctic particularly vulnerable. Modern warming already shows signs of reaching the same threshold. <\/p>\n If temperatures rise just a few degrees more, widespread thawing could release massive stores of carbon and methane trapped in frozen ground.<\/p>\n Past warmth, future threat<\/p>\n \u201cOur results highlight how sensitive the Arctic climate is and that every fraction of a degree matters,\u201d said Moseley. The cave\u2019s message is clear: even small changes can have long-lasting consequences.<\/p>\n Back then, warmth reshaped Greenland\u2019s landscape. Today, it could reshape our planet\u2019s future. <\/p>\n \u201cEvery small step we take to limit warming<\/a> helps to avoid these feedbacks and to reduce the impacts of climate change,\u201d she added.<\/p>\n Those ancient layers of calcite, hidden deep beneath Greenland\u2019s Arctic ice, aren\u2019t just relics. They\u2019re reminders that even the coldest places on Earth remember how to melt.<\/p>\n<\/p>\n Credit: University of Innsbruck<\/p>\n The study is published in the journal Nature Geoscience<\/a>.\u00a0<\/p>\n \u2014\u2013<\/p>\n Like what you read? Subscribe to our newsletter<\/a> for engaging articles, exclusive content, and the latest updates.\u00a0<\/p>\n Check us out on EarthSnap<\/a>, a free app brought to you by Eric Ralls<\/a> and Earth.com.<\/p>\n \u2014\u2013<\/p>\n","protected":false},"excerpt":{"rendered":"The Arctic wasn\u2019t always frozen and lifeless. Millions of years ago, parts of northern Greenland were wet, green,…\n","protected":false},"author":2,"featured_media":248322,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[22],"tags":[64,63,75,128],"class_list":["post-248321","post","type-post","status-publish","format-standard","has-post-thumbnail","category-environment","tag-au","tag-australia","tag-environment","tag-science"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/248321","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/comments?post=248321"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/248321\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media\/248322"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media?parent=248321"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/categories?post=248321"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/tags?post=248321"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
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