Leap seconds will be abolished immediately

On October 15, member countries of the General Conference on Weights and Measures (CGPM) voted to abolish the leap second. The periodic adjustment has been used to align the world clock with the Sun’s position in the sky while maintaining the stability of atomic-clock-based Coordinated Universal Time.

The CGPM had previously resolved to abolish leap seconds by 2035, but the latest decision takes effect immediately. A replacement “leap time” will probably not be needed for several thousand years, effectively passing the problem to future generations.

Nature | 4-minute read

Artificial intelligence appears in 30% of US doctoral theses

About 30% of science, technology, engineering and mathematics doctoral theses from US universities this year included text generated by artificial intelligence, according to an analysis of more than 226,000 papers.

The study also found that PhD graduates who used AI to write their papers were more likely to pursue careers in industry and less likely to enter academia. Economist and study co-author Daniel Gross said this could be because students feel unappreciated when they use AI in work outside academia.

Nature | 5-minute read

Reference: National Economic Research Institute research report (not peer reviewed).

Could wood-based blankets slow permafrost emissions?

A startup called PermaC is developing a way to prevent greenhouse-gas emissions from permafrost by stabilizing the soil with an insulating “blanket” made from wood-based materials.

If successful, the method could become the first tool designed to directly stop greenhouse gases from escaping permafrost. Those emissions are estimated to be equivalent to Japan’s annual emissions. However, significant challenges remain before this type of approach could be deployed at a meaningful scale.

Nature | 7-minute read

Features and insights

Radiocarbon dating suggests the Inca Empire lasted longer

Radiocarbon dating is changing views of the Inca Empire’s lifespan. The empire was once thought to have lasted only 94 years, based on Spanish colonial chronology.

Although radiocarbon dating remains uncertain, its accuracy is improving through advanced statistical models, comparisons with tree-ring records and a better understanding of how carbon-14 isotope levels vary from place to place.

New data suggests that the Inca Empire began earlier and lasted longer. The findings could change how archaeologists understand the way the Incas accomplished their conquests.

Science | 19-minute read

Tree rings reveal Indigenous forest-management practices

Researchers are using dendrochronology, or tree-ring dating, to learn more about the history of forest management by Indigenous peoples in North America.

Critics disagree about whether ancient wood contains evidence of coordinated, human-made fires. However, the evidence supports traditional knowledge “encapsulated in our language, stories and ritual procedures,” says Muskoke scholar Marcus Briggscloud. Forest ecologist Michael Stambaugh agrees: “The trees are the witnesses.”

The New Yorker | 20-minute read (intermittent paywall).

Artificial intelligence, natural order and the search for meaning

Artificial intelligence entities embrace the beauty of natural order, become reality and lead an android to realize that there is more to life than its programming.

A pianist who has never played.

Nature | 6-minute read and Nature | 6-minute read

Conservation areas cover more land than official figures suggest

According to official statistics, conservation areas cover 18.5% of Earth’s land—well below the government’s pledged target of 30% by 2030.

A new study suggests that figure is an underestimate and that conservation areas actually cover about 27% of the world’s land. But simply adding more land is not enough to protect biodiversity, says ecologist Bob Smith.

“By fixating on meeting area targets, governments often don’t spend more money,” he says. Instead, available funds are “spread even thinner.”

Nature Podcast | 21-minute listen

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Can you find the penguin?

Today, Lief Penguinson looks up at one of Sweden’s highest waterfalls, Njpeskal Falls in Hrfjallets National Park. Can you find the penguin?

The answer will be in Monday’s email. Many thanks to Nature Briefing photo editor and penguin wrangler Tom Horton.

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