What the scientists are saying…
The vegetation covering the Alps
The Alps are turning green, owing to plant life thriving in a warmer, wetter climate, a study has found. Researchers from two universities in Switzerland examined satellite data from 1984 and 2021, and calculated that the vegetation above the tree line had increased in almost 80% of the terrain observed, while the amount of snow cover had decreased in 10% of the area. “The scale of the change has turned out to be absolutely massive in the Alps,” said Prof Sabine Rumpf of the University of Basel, author of the study, which was published in Science. “The Alps are becoming greener because plants are colonising new areas and the vegetation is generally becoming denser and taller.” These plants will absorb some CO2, she added, but any positive consequences are likely to be outweighed by the negative outcomes. More vegetation is liable to speed up the snow melt, and reduce snow cover. That, in turn, further weakens the albedo effect, by which frost reflects sunlight back into the atmosphere.
Tyre pollution is the real problem
For years, clean air initiatives have focused on exhaust emissions; but in modern cars, with advanced filters, the tyres are the far more serious source of pollution. A new study has found that used tyres produce 36mg of particles per kilometre, which is 1,850 times more than the average emitted by exhausts. Particles from tyres contain a range of compounds, including carcinogens; and 11% of the particles are ultrafine. These are of particular concern, as they are tiny enough to enter organs via the bloodstream. “Tyres are rapidly eclipsing the tailpipe as a major source of emissions from vehicles,” said Nick Molden of Emissions Analytics, the firm that did the research. “Tailpipes are now so clean for pollutants that, if you were starting out afresh, you wouldn’t even bother regulating them.” Cars getting heavier, causing tyres to wear out faster, is exacerbating the problem; batterypowered electric cars tend to be heavier than those powered by fossil fuel. Driver behaviour is also a factor: driving aggressively leads to more tyre emissions.
Secrets of the giraffe’s neck
How did the giraffe get its long neck? It needs a good reason, because its length is quite troublesome. The animals have to have very high blood pressure, to enable their hearts to pump blood two metres up the neck to the head, which has in turn required a range of other adaptations. One theory is that giraffes evolved their longer necks to reach higher leaves on trees. It makes sense, but it has some holes: giraffes tend to eat at lower levels, and there is no evidence that taller giraffes are more likely to survive droughts, when competition for food is fierce. Now a study has found evidence to add weight to an alternative theory, which is that the necks evolved as fighting weapons, through sexual selection. A team of palaeontologists examined the fossilised remains of an ancient giraffe ancestor found in China, and concluded that with its bulky vertebrae, and helmetlike head, it was adapted to absorb and deliver head-cracking collisions, to fend off love rivals. They suggest that this may have driven the elongated neck, which then conferred a further advantage in additional foraging capability.
A drug to combat obesity
Treating people who are obese – but not diabetic – with the type 2 diabetes drug tirzepatide can produce “unprecedented” levels of weight loss in many patients, researchers say. In the trial, involving 2,539 overweight adults, 94.5% of whom were obese, those who were injected with the highest level of the drug lost an average of nearly 21% their body weight. The participants had been divided into four groups, and given weekly injections of the drug, in 5, 10 or 15mg doses, or a placebo. All were asked to follow a low-calorie diet, and to exercise; and were given regular counselling to help them. Any side effects were mild to moderate, and 81% of the participants completed the study. Of these, the average weight loss among those who received the lowest dose of the drug was 16.1kg; among those who had the highest dose it was 23.6kg. By contrast, those in the placebo group lost just 2.4kg. More than 90% who took 15mg of the drug, which works by making people feel full, lost at least 5% of their bodyweight, compared to only 35% in the placebo group.