This El Niño is set to be the largest on record by a ‘mind-blowing margin’

Hello Nature readers,
Today we hear forecasts that this year’s El Niño will combine with global warming to push temperatures to new heights. Plus, we discover that there was a boom in languages at the dawn of farming and learn what The Odyssey has to tell us about the science, medicine and technology of the Homeric world.

This El Niño is on track to be the largest ever

The El Niño climate pattern that’s strengthening in the Pacific Ocean is on track to be the largest one in at least 150 years, researchers say. If current forecasts pan out, the El Niño will unleash a surge of heat from the ocean that, combined with human-induced global warming, will probably make next year the hottest on record. That an El Niño is occurring now isn’t surprising in itself, but the peak of this event is set to surpass the previous record-holder by “truly, a mind-blowing margin”, says climate scientist Zeke Hausfather.

Humans spoke tens of thousands of languages

Humanity might have spoken tens of thousands of languages between 3,000 and 1,000 years ago, which have dwindled down to the around 7,500 unique languages used today. Researchers estimate that the number of spoken languages ballooned starting at the end of the last glacial period, as humans moved from hunter-gatherer groups into agricultural communities. After peaking around 2,000 years ago, the number began to fall again, possibly because of the spread of powerful, monolingual cultural groups through conquest and trade.

US to limit the stay of international PhDs

From mid-September, the US government will limit international students to no more than four years in the United States unless they can secure an extension. The move overturns a decades-old policy that allows students to stay for the duration of their academic programme. The government says that the new rule will “combat rampant visa abuse”, but some researchers worry that it will curtail the flow of international students into the US, since it takes more than 5 years on average to complete a PhD in science or engineering.

At-home breath test measures fat burning

A handheld breathalyser can measure when the body is burning fat in real time. The device measures the level of acetone, a compound produced by the breakdown of fatty acids in the liver, in a person’s breath. The user’s exhalation is guided by a smartphone app, which improves the device’s accuracy, says the team who developed it. The device could be used by people trying to manage weight loss, although researchers say that it should be tested in more people to confirm that its results are accurate.

The Odyssey tells tale of ancient knowledge

Homer’s epic The Odyssey has roots as far back as 1600 BC — and gives glimpses into the science, medicine and technology of the Homeric world. For example, a spear plunged into the Cyclops’s eye sizzles like a quenched blade — a sound that would be known to someone familiar with forging steel, not pure iron or bronze. This suggests the detail was added when the story was first committed to text after centuries of being told orally. There are even nuggets of astronomical knowledge: the poem’s mentions of the Pleiades, Hyades and Orion show that “these names go back to the very beginning of Greek astronomy”, says historian James Evans.

Futures: Eyes upturned towards infinity

An off-world settler is reminded why she left Earth in the latest short story for Nature’s Futures series.

In Afghanistan, a female doctor perseveres

In a rare dispatch from Afghanistan, where the Internet and access to communication are often restricted, a female physician describes her attempts to provide health care in remote rural areas. She is one of the few such professionals still working in a country where the Taliban has banned higher education and most forms of paid employment for women. Taliban rules say she can’t work without a male ‘guardian’, and many of the women she treats are similarly trapped in their homes. Nevertheless, she examines up to 20 patients a day, sometimes knocking on doors to find those who need her. “They need even the little that I can do for them,” she says.

Podcast: what makes a moon?

Researchers have spotted an ‘exosatellite’ about the mass of Jupiter orbiting a brown dwarf, a kind of ‘failed’ star. This orbiter might sound a lot like a moon, but it’s “very planet-like, and so it’s hard for us to call that a moon”, astrophysicist and study co-author Kevin Hoy tells the Nature Podcast. Part of the problem is that exomoons — those beyond our Solar System — are notoriously hard to spot, and astronomers disagree on how to know if one has been detected.