A hidden Alzheimer’s tipping point may decide who gets dementia - Science Daily

The prediction, although uncertain, was terrifying: A vast system of Atlantic currents called the Atlantic Meridional Overturning Circulation (AMOC) that shapes weather around the world could collapse around 2057. Behind this theory were two sibling scientists, Susanne and Peter Ditlevsen, and their work had kindled an international debate about one of the planet’s most feared tipping points. When San Francisco–based journalist Gregory Barber first read about their startling prediction, he thought he had found a character-driven climate story. But as Barber reported a piece for Quanta Magazine, he became intrigued by a more basic and unsettling question: What, exactly, is a tipping point? He realized that although the phrase “tipping point” seems intuitive to most of us (think of tipping over a chair), we don’t actually know what a tipping point is. He decided to turn his story into an explanatory one—taking us deep into the math of tipping points and showing us how important they are and how uncertain they can be.

Parts of the Earth’s climate system can change abruptly once warming pushes them beyond critical thresholds. The Greenland and Antarctic ice sheets, the Amazon rainforest, coral reefs and major ocean currents are all among the systems containing potential climate tipping points. These climate systems are known as tipping elements, and research into them has expanded rapidly. But it has not expanded evenly. In a new study published in Proceedings of the National Academy of Sciences, colleagues and I examined 20,736 scientific publications on 14 climate tipping elements published between 2000 and 2025. We wanted to know where scientific attention has accumulated, and whether the systems with relatively low estimated warming thresholds tend to receive more of it. An uneven research landscapeThe Greenland Ice Sheet dominates the studies we analysed. It appeared in 4,141 publications — 20 per cent of the entire dataset. By contrast, abrupt thaw of permafrost in boreal forests just below the Arctic appeared in just 139 papers, or 0.7 per cent. The North Atlantic subpolar gyre, a system of ocean circulation south of Greenland, accounted for 649 papers, or 3.1 per cent.

Climate science's most important risk-mapping tool — the tipping-point literature — has a structural allocation problem, and a new peer-reviewed audit just put a number on it. A study published October 6 in the Proceedings of the National Academy of Sciences analyzed 20,736 peer-reviewed publications covering 14 climate tipping elements released between 2000 and 2025, then compared that research attention against each system's estimated warming threshold. The finding: scientific attention does not track risk. Systems with warming thresholds as low as 1.5°C — the same threshold as the much-studied Greenland ice sheet — are receiving a fraction of its research investment, leaving science without the observational infrastructure or early-warning capability it would need to detect a threshold crossing before it becomes irreversible. The implications extend directly to climate governance: the risk assessments that shaped the Paris Agreement's 1.5°C target were built on this same literature. If the literature is structurally biased — overconfident where research is dense, silent where it is thin — then the danger map policymakers are using is systematically distorted.

Lawrence Livermore National Laboratory researcher Isaiah Santistevan led the development of three-dimensional simulations exploring how a nuclear device could deflect or disrupt an asteroid threatening Earth. Credit: Blaise Douros/LLNL Lawrence Livermore National Laboratory (LLNL) researchers are developing three-dimensional simulations to examine how a nuclear device could be used to deflect or potentially disrupt an asteroid threatening Earth.