Arctic speleothems reveal nearly permafrost-free Northern Hemisphere in the Late Miocene
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Abstract
Arctic warming is happening at nearly four times the global average rate. Long-term trends of permafrost dynamics cannot be estimated directly from monitoring of present-day thaw processes, requiring paleoclimate-proxy information. Here we use cave carbonates (speleothems) from a northern Siberian cave to determine when the Northern Hemisphere was mostly permafrost-free. At present, thick continuous permafrost in this region prevents speleothem growth. In a series of partially eroded caves, speleothems grew during the late Tortonian stage (8.68 ± 0.09 Ma), a time when the geographic position of this site was already similar to today. Paleotemperatures reconstructed from speleothems show that mean annual air temperatures (MAAT) in the region were + 6.6°C to + 11.1°C, when contemporary global MAAT were ~ 4.5 °C higher than modern. Our findings provide direct evidence that warming to Tortonian-like temperatures would leave most of the Northern Hemisphere permafrost-free. This may release up to ~ 130 petagrams of carbon, enhancing further warming.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Arctic speleothems reveal nearly permafrost-free Northern Hemisphere in the Late Miocene |
| Series title | Nature Communications |
| DOI | 10.1038/s41467-025-60381-5 |
| Volume | 16 |
| Publication Date | July 01, 2025 |
| Year Published | 2025 |
| Language | English |
| Publisher | Nature |
| Contributing office(s) | Alaska Science Center Geology Minerals |
| Description | 5483, 13 p. |
| Country | China, Mongolia, Russia |
| Other Geospatial | Siberia |