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Mint
3 days ago
- Science
- Mint
Climate change may make it harder to spot submarines
THE PENTAGON 'does not do climate-change crap", said Pete Hegseth, Donald Trump's defence secretary, on March 9th. 'We do training and warfighting." Fair enough. But a new NATO study illustrates how closely the two are linked. A submarine must remain undetected, eluding hydrophones towed by ships, dropped from planes and strung along the seabed. Just how quiet it needs to be depends on the surrounding water's acidity, salinity and temperature. Higher carbon-dioxide levels in the atmosphere change all these things. The gas's mere presence acidifies seawater. Its warming effects alters its temperature, and by melting ice changes the salinity, too. Sources of ambient noise such as winds, waves and whales are all affected. And the changes all differ from place to place. To work out the consequences for submariners, a team led by Andrea Gilli of the NATO Defence College in Rome and Mauro Gilli of ETH Zurich used computer modelling to examine how sound travelled through deep water in the past (from 1970 to 1999) and how climate models suggest it will do so in the future (from 2070 to 2099). The researchers originally published their findings in the Texas National Security Review in 2024. In the North Atlantic, a crucial battleground between Russian subs and NATO sub-hunters—as well as in the area between the first and second island chains in the Western Pacific, just to the east of Japan, Taiwan and the Philippines—detection will become harder. In the Bay of Biscay, off the French coast, a sub that could once be detected from 60km away will be spotted only at 20km. In the Sea of Japan, however, local conditions will make life easier for the hunters. North Korean submarines operating in those waters at a depth of 100m could previously get to within 10km away without detection. In the future, estimate the authors, they could be seen from 45km off. The hypothetical scenario the study considers is based on a worst-case outcome in which nothing has been done to reduce greenhouse-gas emissions; a trajectory most scientists now consider unrealistic. All the same, the trends identified in the paper are noteworthy. In recent years there has been much talk of new detection methods making the oceans more transparent. In fact, argue the authors, the seas might become more opaque. Curious about the world? To enjoy our mind-expanding science coverage, sign up to Simply Science, our weekly subscriber-only newsletter.
Mint
22-05-2025
- Health
- Mint
Rumours on social media could cause sick people to feel worse
THE PLACEBO effect is a well-known example of the brain's power over the body, allowing people who are poorly or in pain to improve if they are led to believe they are being treated. The opposite, however, is also possible: patients who believe that procedures will cause them to suffer ill effects can make themselves worse. The roots of this anti-placebo, or nocebo, effect are difficult to untangle. But in a paper in Health Psychology Review, researchers in Australia have pooled the available evidence and ranked the contributing factors. Misinformation on social media seems to come near the top. In fact, what psychologists call social learning—the drawing of inferences from the views of others—was found to be as powerful as lived experience, and more influential than information given by a doctor. This is a problem, says Cosette Saunders, a psychologist at the University of Sydney and lead author of the study. Social learning may not be able to spread infection or cause new disease, but it can drive harmful side-effects. And managing these side-effects costs health systems around the world billions of dollars. Take cancer treatment. In recent years, new drugs have emerged to control the side-effects experienced by people receiving chemotherapy. But Dr Saunders says that vomiting and nausea have not come down in cancer patients by as much as expected. Social learning may be responsible. 'They'll say, their mother-in-law had chemo twenty years ago and she was vomiting every single day," Dr Saunders says. 'Those kinds of long-held beliefs are influencing them now, even though the medical landscape has changed." Something similar appeared to be happening during the covid-19 pandemic: studies in America and Australia found people who were most exposed to the idea that vaccination provoked side-effects were also most likely to report them. Though the impact of the placebo effect has been recognised for centuries, work on the nocebo effect is much newer. Only in the past two decades have many scientists been convinced of its real-world impact, helped by studies that demonstrate how a negative attitude can lead to physical symptoms such as increased heart rate and physiological arousal. The conclusions of the Australian analysis are stark about the power of social learning. But, says Dr Saunders, it is hard to know how much of these effects are down to social-media use as opposed to, say, chatting with friends at the pub. Dr Saunders' lab is one of many now trying to find ways to minimise the damage. One possibility is to balance warnings of nasty side-effects with positive testimony from patients who had no problems. If she finds something that works, she'll pass it on. Curious about the world? To enjoy our mind-expanding science coverage, sign up to Simply Science, our weekly subscriber-only newsletter.
