What the scientists are saying…
China set for lethal heatwaves China’s most populous region is at risk of becoming barely habitable by the end of the century owing to global warming. According to a new report, the north plain – home to about 400 million people, and a centre for food production – is likely to be subjected to repeated heatwaves so intense humans could not withstand them. The warning is based on an analysis of likely wet-bulb temperatures (WBT) that are a combination of heat and humidity. Once the WBT reaches 35°C, people cannot cool themselves by sweating, and even in the shade they’re liable to die within six hours. Using climate models, the team predict that unless carbon emissions are cut significantly, the plain – which runs from Beijing to Shanghai – will repeatedly experience WBTS of 35°C between 2070 and 2100. And even if cuts are made, it is still at risk of heatwaves in which the WBT exceeds 31°C – a level so dangerous, outdoor work is impossible. Climate change is the main factor, but the fact that the north plain is so heavily irrigated adds to the problem: evaporation leads to higher humidity, and water vapour is a greenhouse gas in itself. “Continuation of current global emissions may limit the habitability of the most populous region of the most populous country on Earth,” said Professor El-fatih Eltahir, of the Massachusetts Institute of Technology.
Natural selection at speed In a rare example of “natural selection by disaster”, the body shape of a lizard species appears to have been modified by a pair of devastating hurricanes. A group of international researchers travelled to the Turks and Caicos islands in the Atlantic last summer to monitor a programme to eradicate rats. Before they left, they took measurements of the local Anolis scriptus lizard, so that they could chart its post-rodent evolution. But when hurricanes Irma and Maria battered the islands in quick succession, they seized the chance to study a different kind of evolutionary change. Returning, they found that the toepads and front legs of the remaining lizards were larger than those of the pre-storm population. This made sense: these animals would have been better able to cling on during the storms. More perplexing was the discovery that their back legs were shorter. “This was a real head-scratcher,” said Harvard’s Dr Colin Donihue, who led the research. It was only when the team placed the lizards on wooden posts and turned on a leaf blower that they solved the puzzle. As the lizards clung on, their hind legs jutted out, catching the wind like sails and ripping them from the posts (into safety nets). “With shorter thighs, you’re catching less wind,” Donihue said. Dashing hopes for life on Mars Tech billionaire Elon Musk reckons he can make Mars habitable by blasting it with nuclear rockets – but there’s just one problem: it won’t work. The idea is that the explosion would release CO2 stored in Mars’s rocks and polar ice caps back into its atmosphere, raising its pressure, heating the planet and allowing liquid water to remain on the surface. But according to a Nasa study, there is not enough carbon dioxide on the surface of Mars to thicken the atmosphere to the extent necessary for it to be terraformed (turned into an Earth-like place). Even if turns out that there is CO2 stored at a deeper level, there isn’t the technology to access it – not at the moment, at any rate. “It’s not that terraforming itself isn’t possible, it’s just that it’s not as easy as some people are currently saying,” said Professor Bruce Jakosky, of the University of Colorado Boulder. “We can’t just explode a few nukes over the ice caps.”
Abstention linked to dementia It’s quite clear that alcohol can damage the brain – but could it, in moderation, have a protective effect? That is the possibility raised by a new study of 9,000 civil servants in London, which found that those who had consumed alcohol within recommended limits in middle age were significantly less likely to develop dementia in later life than those who abstained (but heavy drinkers were at even greater risk). The abstainers also had higher rates of diabetes and cardiovascular disease, conditions associated with dementia, according to the BMJ report. However, this was only an observational study, and it acknowledged that the abstainers may have been heavy drinkers in the past – and may have foresworn drink for that reason.