Arctic permafrost holds roughly 1,300 gigatonnes of ancient organic carbon \u2014 the compressed remains of plants frozen for millennia. As temperatures rise and coastlines crumble into warming seas, that carbon is increasingly on the move, flushing into the Arctic Ocean at a rate that could climb by more than 150 percent before the century ends.<\/p>\n
To find out where it all goes, researchers pulled sediment cores from the frigid waters off Herschel Island, Canada \u2014 hunting for an answer to one of climate science’s most consequential open questions<\/strong>.<\/p>\n Permafrost isn’t just frozen ground \u2014 it’s a long-term carbon archive<\/strong>. Arctic soils hold roughly 1,300 gigatonnes of organic carbon, most of it the compressed remains of plants that died and were locked in ice over thousands of years. Another 400 gigatonnes sit in ocean sediments and river deltas nearby.<\/p>\n The Arctic is warming faster than anywhere else on Earth. That acceleration is thawing frozen ground from the inside out, crumbling coastlines into the sea, and setting carbon in motion that spent millennia going nowhere.<\/p>\n Currently, up to 0.02 gigatonnes of land-based carbon enter Arctic waters each year<\/strong>. Dr. Manuel Ruben, lead author of the study from the Alfred Wegener Institute<\/a>, notes that forecasts suggest that outflow could rise by 70 to 150 percent by 2100. Until this research, scientists had little clarity on what happens next \u2014 whether that carbon reenters the atmosphere as a greenhouse gas or stays locked away somewhere new.<\/p>\n Researchers from the Alfred Wegener Institute and MARUM \u2014 the Centre for Marine Environmental Sciences at the University of Bremen \u2014 traveled to the frigid waters off Qikiqtaruk, also known as Herschel Island, on Canada’s Arctic coast. They collected sediment cores from multiple sites, each capturing roughly 50 years of accumulated material: a layered record of how carbon had built up on the seafloor over time.<\/p>\n The team didn’t just catalog what was there. They analyzed pore water \u2014 the fluid trapped between sediment particles<\/strong> \u2014 to measure how much CO2 microorganisms had released after consuming organic matter, revealing how active the decomposition process really was.<\/p>\n Carbon isotopes<\/strong> provided the chemical fingerprints. The 13C isotope indicated whether microbes had consumed carbon from land or from the sea, while the 14C isotope went further still, distinguishing between ancient permafrost carbon<\/a> and fresher organic material from recent algal remains.<\/p>\n The results were more reassuring than many scientists had anticipated. Only about 10 percent of the organic carbon swept into the ocean is converted by microorganisms into gases that can rise into the water column and eventually reach the atmosphere. The rest becomes buried and preserved in seafloor sediment. It doesn’t disappear, but it doesn’t warm the planet either<\/strong>.<\/p>\n “Although the sea here carries away huge quantities of organic carbon from the coast, surprisingly little of it ends up in the ocean’s active carbon cycle,” said Ruben.<\/p>\n One important caveat remains. Some permafrost carbon may already have broken down before reaching the seabed, which means the full accounting isn’t complete. The findings, published in Nature Geoscience<\/em>, represent a significant step forward \u2014 not the final word<\/strong>.<\/p>\n A key reason so much ancient carbon stays buried comes down to microbial taste. The organisms living in Arctic seafloor sediments are selective feeders, and they have a strong preference for fresh material<\/strong>.<\/p>\n “The sediment is home to ‘gourmet’ bacteria that apparently prefer fresh carbon stemming from, for example, more recent algal remains over the ‘old’ carbon from permafrost deposits,” explained Prof. Gesine Mollenhauer, a geochemist at the AWI and co-author of the study.<\/p>\n This selectivity carries real climate implications<\/strong>. Because microbes favor newer marine organic matter, older permafrost carbon is far less likely to be broken down into greenhouse gases than earlier models assumed \u2014 it tends to settle into the sediment and stay there. Without isotopic analysis to distinguish carbon sources at the atomic level, that microbial preference would have remained invisible.<\/p>\n The stakes extend well beyond atmospheric chemistry. Accelerating coastal erosion doesn’t just release carbon<\/strong> \u2014 it dumps sediment and dissolved organic matter into nearshore waters, reshaping the ecosystems that depend on them.<\/p>\n Freshly eroded fragments make coastal waters cloudy. Dissolved organic carbon darkens them further. Both effects cut the sunlight reaching algae and other primary producers that anchor the Arctic food web<\/a>, with consequences rippling up to fish, crustaceans, seals, and the communities that rely on those resources.<\/p>\n Researchers plan to investigate these ecosystem effects during the international Arctic Pulse<\/em> campaign in 2027, using the Polarstern icebreaker, AWI research aircraft, and land-based observation sites. The study also gives climate models a more precise foundation for predicting how permafrost thaw will reshape the global climate system \u2014 and as the Arctic changes faster than models can keep up, that precision may matter more than ever<\/strong>.<\/p>\n","protected":false},"excerpt":{"rendered":" Arctic permafrost holds roughly 1,300 gigatonnes of ancient organic carbon \u2014 the compressed remains of plants frozen for millennia. As temperatures rise and coastlines crumble into warming seas, that carbon is increasingly on the move, flushing into the Arctic Ocean at a rate that could climb by more than 150 percent before the century ends. … Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":33301,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"rank_math_focus_keyword":"Arctic permafrost","rank_math_title":"","rank_math_description":"Discover how melting Arctic permafrost is releasing carbon into the ocean and its impact on climate change and marine ecosystems.","footnotes":""},"categories":[24],"tags":[],"class_list":["post-31932","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-climate"],"_links":{"self":[{"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/posts\/31932","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/comments?post=31932"}],"version-history":[{"count":0,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/posts\/31932\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/media\/33301"}],"wp:attachment":[{"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/media?parent=31932"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/categories?post=31932"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/tags?post=31932"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}A frozen carbon vault on the edge of collapse<\/h2>\n
Reading the seafloor like a carbon ledger<\/h2>\n
The surprising verdict: most carbon stays buried<\/h2>\n
‘Gourmet’ bacteria with a preference for the fresh<\/h2>\n
Beyond emissions: what carbon runoff means for Arctic life<\/h2>\n