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Around 56 million years ago, a sharp rise in carbon dioxide in the atmosphere led to severe global warming that transformed the planet’s surface, which led to a widespread decline in forest cover. This decline during the Paleocene–Eocene Thermal Maximum (PETM) could have parallels for what could happen as a result of human-driven climate change, say researchers. The PETM isn’t a perfect analogue for modern day, but “what we’re looking for is guides from the past about what can happen”, says palaeoclimatologist Gabriel Bowen.

Nature | 5 min read

Reference: Science paper

The US Food and Drug Administration (FDA) has approved a new mRNA-based flu vaccine for adults aged 50 or older. The vaccine is also being reviewed by regulatory agencies in the European Union, Canada and Australia. An mRNA platform allows for the vaccine to be rapidly reformulated to match circulating influenza strains, which could be a “game changer”, says public-health researcher Emanuele Montomoli. But some scientists still have questions about how well this vaccine will perform when it’s rolled out to millions of people. “We will have to wait for the real-world data”, Montomoli says.

Nature | 5 min read

Neighbourhoods in the United States that experienced a growth in their population of undocumented immigrants between 2010 and 2018 also saw property-related and violent crime fall, not rise. The study, which analysed non-public demographic data for 11,500 neighbourhoods in more than 100 cities, found no link between immigration and crimes such as homicide and motor-vehicle theft, but found higher rates of robberies. The research team hope the findings can inform public perception of immigration, which often “doesn’t match the evidence that’s been produced from researchers”, says Ben Brindle, who studies migration.

Nature | 5 min read

Reference: Journal of Urban Affairs paper

In response to the European Union’s AI Act, artificial-intelligence giant Anthropic has announced that text generated by any of its Claude models launched on or after 2 August will be invisibly embedded with a watermark that indicates the output was written by AI. Watermarks might help to curb undisclosed use of AI in some instances, say researchers. But such indicators can be removed easily, and the absence of a watermark shouldn’t be taken to mean that text was definitely written by a human, they say.

Nature | 5 min read

Features & opinion

China’s research sector needs to reassess how it incentivizes early-career researchers to relieve some of the immense pressures they face, argues vaccine researcher Ming Li. The current system funnels resources to researchers selected by prestigious talent-acquisition schemes and measures prestige based on titles, commonly called academic ‘hats’, that can only be gained through these programmes. The system should separate talent titles from resource-allocation processes, and set consistent career-advancement rules to nurture a research environment that focuses on tackling difficult research questions, not just publication rates, Li argues.

Nature | 5 min read

The perfect cup of tea proves too tempting in The recovered notes of Professor Alborough, and an elderly woman fools a system that refuses to accommodate her in System lag.

Nature | 6 min read & Nature | 7 min read

Andrew Robinson’s pick of the top five science books to read this week includes a look into the lives of ‘outsider animals’ and a spotlight on Albert Einstein’s lesser-known musical abilities.

Nature | 3 min read

Researchers have developed a probiotic that can actively respond to high blood sugar levels, which they hope could one day be a new treatment for diabetes. The treatment uses engineered Escherichia coli as a living sensor, which responds to high blood-glucose levels by releasing molecules that trigger the secretion of insulin. “We thought there was an opportunity to develop a treatment that behaves more like the body itself that can respond to changes in glucose rather than simply delivering a fixed amount of medicine,” says biologist and study co-author Ningzi Guan.

Nature Podcast | 20 min listen

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Today Leif Penguinson is wandering the atmospheric forests of La Gomera, one of the Canary Islands, Spain. Can you find the penguin?

The answer will be in Monday’s e-mail, all thanks to Briefing photo editor and penguin wrangler Tom Houghton.

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Jacob Smith, associate editor, Nature Briefing

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