What the scientists are saying…

Threat to Himalayan ice caps At least a third of the Himalayas’ ice will melt by 2100, even if aggressive steps are taken to curb global warming, scientists have warned. The landmark report into the impact of climate change on the Hindu Kush-himalayan (HKH) region predicts that between 36% and 66% of the region’s ice will disappear, with the lower level of melting reliant on global temperature rises being within 1.5°C, which is considered optimistic. About 250 million people live in the HKH region – which harbours more ice than anywhere outside the Arctic and Antarctica – and a further 1.65 billion are reliant on the great rivers that flow from its peaks into China, India, Pakistan and other countries. The report predicts that river flows will first increase – potentially causing widespread flooding – and then start declining from about 2060. As well as affecting supplies of drinking water and hydroelectricity, this is likely to have a very serious impact on the region’s agriculture. “This is the climate crisis you haven’t heard of,” said Dr Philippus Wester of the International Centre for Integrated Mountain Development, which compiled the report. “The consequences are pretty extreme.”

Mussels lose their grip Exposure to microplastics could be depleting mussels of their most valuable skill: their ability to cling tightly to rocks. When a team from the Anglia Ruskin University exposed blue mussels to doses of non-biodegradable microplastics, they started producing fewer byssal threads – the thin fibres the creatures use to fix themselves to rocks and ropes. After 52 days, the mussels could be dislodged from their attached position with half as much force as was required to remove a control group, the researchers found. If, as seems likely, mussels in the wild are also ingesting plastic, that could have an impact on an entire marine ecosystem. Mussels’ ability to grip makes them less vulnerable to predators and lets them band together into beds, or “reefs”, which act as nurseries for juvenile fish, and provide habitats for many other sea animals.

Did colonisation trigger freeze? Anthropogenic climate change may not be as recent a phenomenon as we assume: scientists now think that the “Little Ice Age” of the 16th and 17th centuries – when global temperatures fell by half a degree and the Thames in London routinely froze over – could have been caused in part by the colonisation of the Americas. In the century after Columbus made landfall there in 1492, an estimated 55 million Native Americans – about 90% of the pre-existing population – perished, many of them killed by European diseases to which they had no immunity. As a result, researchers from UCL calculate that 56 million hectares of farmland were abandoned. This land would have then been reclaimed by trees and other vegetation, which would have sucked CO2 from the atmosphere, creating a cooling that could have helped cause the Little Ice Age – an event previously ascribed to natural events such as volcanic eruptions. (Antarctic ice core samples confirm there was a drop in atmospheric CO2 at this time.) “What’s interesting is that we can see natural processes giving a little bit of cooling, but actually to get the full cooling – double the natural processes – you have to have this genocide-generated drop in CO2,” said co-author Professor Mark Maslin.

Bees can “add and subtract” For creatures with such tiny brains, bees are surprisingly good at mental arithmetic, scientists claim. A team in Melbourne gathered 14 bees, and used a maze-based reward system to train them that yellow meant “minus one”, and blue meant “plus one”. On entering the Y-shaped maze, the bees would see a number of shapes in either blue or yellow; at the fork, they had to choose between two more sets of coloured shapes – with either one more than in the original set, or one less. If they chose the set that corresponded to the plus or minus colour at the start, the bees got a drop of sugar water; if they picked the wrong one, they got a drop of unpleasant quinine. After completing 100 training exercises, the bees picked the right route two-thirds of the time – more than chance – suggesting they can count, add and subtract (though it may just be that they can distinguish between more and less).