What the scientists are saying…
Mammals turning into night owls
Many mammal species are so distressed by human activity, they are starting to live by night just to get away from us, a study has suggested. Researchers in the US drew on data from more than 70 previous studies to get an impression of 62 mammal species. When they cross-referenced the results with levels of human disturbance – everything from road-building to hiking – they found that higher levels were associated with a 1.36 times increase in nocturnal activity, on average. The phenomenon could be observed regardless of the type of human interference, and persisted when a species’ habitat was unchanged, leading the researchers to conclude that fear must be its main driver. The earliest mammals were exclusively nocturnal, and are thought to have only started venturing out in daylight once the dinosaurs had become extinct. The University of California, Berkeley’s Kaitlyn M. Gaynor, who led the research, said that humans were just as much of a “terrifying force” as dinosaurs, and were driving mammals “back into the night”. Writing in the journal Science, she and her colleagues warned that the trend could affect some mammals’ eating habits, with knock-on consequences for other species.
China’s solar motorway
The world’s first “solar motorway” has opened to traffic in the Chinese city of Jinan, reports The Times. For the pilot project, on a kilometre-long stretch of highway, solar panels capable of powering street lights, road signs and hundreds of nearby houses have been installed under “transparent concrete”. The concrete is said to be tougher than asphalt, and – in theory – capable of withstanding 45,000 cars a day. The engineers responsible for the pilot project have also installed an electromagnetic induction coil in the road, which could in future charge electric vehicles driving along it. Solar roads and pavements are an emerging trend – the Netherlands and France have run small pilot schemes, and Tokyo plans to build solar roads next year – but the technology is still too expensive to be rolled out on a large scale, and it’s not yet clear how resilient the roads are: just days after the Jinan highway opened, a large crack appeared in its surface.
How many nukes do we need?
Nuclear nations need only 100 missiles to serve their strategic ends: any more than that is just a waste of money, scientists have claimed. In the first exercise of its kind, researchers from Michigan Technological University and Tennessee State University analysed how many missiles a country could fire before unleashing a chain of events so catastrophic that scores of its own citizens would die even without retaliation. Using estimates of soot and dust thrown into the air by nuclear blasts, and the consequent blotting of the Sun, the team concluded that if a nation were to detonate fewer than 100 warheads, the consequences, though dire, would mostly be confined to other regions. Above 100, however, and the “environmental blowback” of a oneway strike would wreak global havoc, reducing agricultural output by up to 20% and causing widespread food shortages. Most of the world’s nine official nuclear nations have more than 100 warheads: Britain has 215, France has 300, and America and Russia have around 7,000 each. “With 100 nuclear weapons, you still get nuclear deterrence, but avoid the probable blowback from a nuclear autumn that kills your own people,” said Professor Joshua Pearce, one of the report’s authors.
Keep children to back streets
Children walking along busy roads are exposed to 30% more pollution than adults because their height puts them closer to vehicle exhaust pipes, a new study has found. The researchers asked children and adults to carry pollution monitors as they walked along roads in five of Britain’s biggest cities, as well as in cars driving through traffic. They found that parents could cut their children’s exposure to pollutants by up to 2.5 times if – rather than walk along a busy road – they went on back streets. But going by car is no solution: pollution levels were even higher inside cars on busy roads than on the pavements. Separately, Unicef reported that almost a third of under-18s in Britain live in areas deemed to have unsafe levels of small particulate pollution.