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“Dear diary, it was freezing outside today…” If someone today wrote that in their journal, it might seem like an innocuous enough line, perhaps never to be carefully considered again. But what if, 500 years from now, scientists used that entry about the weather to answer climate mysteries?

Researchers looking to the past have done just that, combing through diaries and other old documents to reconstruct the climate of 16th century Transylvania, part of modern-day Romania. What they found offers a glimpse at how a cooling period called the Little Ice Age may have affected people in the region, the team reports February 12 in Frontiers in Climate. More

Meghan Rosen is a staff writer who reports on the life sciences for Science News. She earned a Ph.D. in biochemistry and molecular biology with an emphasis in biotechnology from the University of California, Davis, and later graduated from the science communication program at UC Santa Cruz. More

Citations

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M. Wolovick, J. Moore and B. Keefer. The potential for stabilizing Amundsen Sea glaciers via underwater curtains. PNAS Nexus. Vol. 2, April 2023, pgad103. doi: 10.1093/pnasnexus/pgad103.

B. Keefer, M. Wolovick and J.C. Moore. Feasibility of ice sheet conservation using seabed anchored curtains. PNAS Nexus. Vol. 2, March 2023, pgad053. doi: 10.1093/pnasnexus/pgad053.

K. Yamazaki et al. Multidecadal poleward shift of the southern boundary of the Antarctic Circumpolar Current off East Antarctica. Science Advances. Published online June 11, 2021. doi: 10.1126/sciadv.abf8755.

R. DeConto et al. The Paris Climate Agreement and future sea-level rise from Antarctica. Nature. Vol. 593, May 6, 2021, p.83. doi: 10.1038/s41586-021-03427-0.

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On a remote island in the Canadian Arctic, researchers have discovered the remains of an ancient glacier that could be over a million years old. The discovery represents what may be the oldest glacier ice ever found buried in permafrost — ground that has been frozen for at least 2 years straight — in the Arctic, researchers report in the January 1 Geology. For researchers keen on studying the glacier, the clock is ticking, as human-caused climate change has exposed the long-preserved ice to melting.

Like notes in the pages of a logbook, the gas bubbles, compounds and particulates trapped in a glacier’s icy layers can yield information about the atmospheres and climates of bygone millennia. But there are precious few reports of such ice older than the last great expansion of the ice sheets, 26,000 to 20,000 years ago. The newfound ice could thus provide researchers with a rare chance to study the climate of the early Pleistocene epoch, during which the Earth underwent episodic ice ages separated by warm periods known as interglacial periods. “These [Pleistocene climate shifts] are analogs for what we can see in the future,” says geomorphologist Daniel Fortier of the University of Montreal.

In 2009, Fortier and colleagues were studying a buried fossilized forest on Bylot Island, in Canada’s Nunavut Territory, when they stumbled across the sites of some recent landslides that had been triggered by the thawing of permafrost. The slides had exposed translucent, layered bodies of ice that had been buried a few meters underground, just above the fossil forest. Much to Fortier’s surprise, radiocarbon dating of organic matter in the ice revealed it was over 60,000 years old. “I was not expecting that at all,” he says.

Researchers are shown digging into the remnant glacier ice, which became exposed by the thawing and slumping of previously frozen ground.Stéphanie Coulombe

What’s more, in the sediment layers overlying the ice, the researchers discovered a flip in the alignment of magnetic minerals that corresponded with a reversal of Earth’s magnetic field roughly 770,000 years old, indicating the ice was at least that old. And previous research had dated the fossil forest upon which the glacier rested to around 2.8 to 2.4 million years ago, providing a maximum possible age for the ice.

The discovery is a testament to the resilience of permafrost, Fortier says. While climate projections suggest permafrost will completely thaw in many regions by the end of the century, this preserved glacier has persisted through interglacial periods that were warmer than today, he notes. “I don’t think permafrost will disappear so fast. The system is more resilient than we think.” More