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Daily briefing: We’re close to reaching a 30% land-conservation target
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Metrologists retire the leap second immediately, instead of by 2035. Credit: Alejandro Martinez Velez/Europa Press via Getty
On 15 October, member states of the General Conference on Weights and Measures (CGPM) voted to scrap the ‘leap second’ — periodic adjustments to the world’s clocks to align time given by the sun’s position in the sky, with the more stable ticking of atomic clocks, known as Universal Coordinated Time. The CGPM had previously voted to ditch leap seconds by 2035, but yesterday’s decision had immediate effect. The leap second’s replacement — the ‘leap hour’ — probably won’t be needed for thousands of years, effectively pushing the issue onto future generations.
Roughly 30% of science, technology, engineering and maths PhD dissertations from US universities this year contained text generated by artificial intelligence, according to an analysis of more than 226,000 dissertations. The study also found that PhD graduates who used AI to help write their dissertations were more likely to pursue a career in industry, and less likely to enter academia. This might be because students feel they won’t be judged for having used AI in jobs outside academia, says economist and study co-author Daniel Gross.
Reference: National Bureau of Economic Research working paper (not peer reviewed)
A start-up firm called PermaC is developing a way to prevent greenhouse-gas emissions from permafrost by stabilizing the soil with an insulating ‘blanket’ of woody materials. If the method works, it could be the first tool to directly forestall greenhouse-gas emissions that are escaping from permafrost — estimated to be equivalent to the annual emissions of Japan. But there are big challenges to rolling out such an approach on a meaningful scale.
As permafrost thaws in the Arctic, a company wants to use blankets to prevent erosion of the landscape.Credit: Jeff Vanuga/Nature Photo Library/Science Photo Library
Radiocarbon dating is transforming our understanding of the lifespan of the Inca empire — which was thought to be just 94 years, on the basis of a Spanish colonial chronicle. Radiocarbon dating has uncertainties, but it’s getting more accurate thanks to advanced statistical models, comparisons with tree-ring records and a better understanding of how carbon-14 isotopes levels vary by location. The new data suggest the Inca empire started earlier and lasted longer, and change archaeologists’ vision of how the Inca made their conquests.
Researchers are using dendrochronology — tree-ring dating — to delve into the history of forest management by Indigenous people in what is now North America. Critics disagree that ancient wood contains signals of a concerted regime of anthropogenic fire — the human use of fire as a tool. But the evidence backs up traditional knowledge that is “encapsulated in our language, stories, and ceremonial protocols”, says Maskoke scholar Marcus Briggs-Cloud. Forest ecologist Michael Stambaugh agrees. “Trees are witnesses,” he says.