What the scientists are saying…

A dangerous appetite for meat The global population’s appetite for meat keeps growing – and is liable to have a “devastating” impact on the environment, a new report has warned. In the past 50 years, per capita meat consumption across the world has nearly doubled, from 23kg a year to 43kg, while total consumption has risen fourfold. And though there are signs that some higherincome countries have reached “peak meat”, the UN has estimated that global consumption will rise a further 76% by around 2050, owing to growing demand from middle-income countries such as China – with huge knock-on effects: livestock farming is a significant contributor to greenhouse gas emissions; it leads to biodiversity loss, as wild land is cultivated to grow animal feed – which in turn puts a strain on water resources. The report, published in the journal Science, warns of severe consequences if action isn’t taken to change people’s diets. “What’s happening is a big concern and if meat consumption goes up further it’s going to be massively more so,” co-author Professor Tim Key, an epidemiologist at the University of Oxford, told The Guardian.

Underground lake found on Mars Astronomers have discovered what appears to be a large liquid water lake beneath Mars’s south pole. Mars was once a warm wet world, but millions of years ago its climate cooled, causing its water to become trapped in ice. Scientists have spotted signs of what might be water flowing intermittently on its surface before, but this is the first clear evidence of what appears to be a stable body of water. The discovery was made by sending radar waves from the European Space Agency’s Mars Express orbiter at the planet’s surface: these penetrated the ice at the Martian south pole and reflected off a substance about a mile underground, which astronomers believe can only be water. The lake is quite big: it is around 12 miles across, and is estimated to be at least one metre deep. However, for its water to remain liquid at such low temperatures, it would have to have a great many salts dissolved in it, and it is not clear if such a briny sludge could support life. “This is certainly not a very pleasant environment,” said Roberto Orosei, of the National Institute for Astrophysics in Bologna.

Hot weather linked to suicide We know that climate change could put our physical health at risk – by, for instance, causing the spread of infectious diseases. Now scientists are warning that it could jeopardise our mental health too. A team at Stanford University looked at suicide rates across the US and Mexico over several decades, and tracked these against temperature variations. They found that when the temperature was 1°C above average in a given month, the suicide rate increased – by 0.7% in the US and 2.1% in Mexico. The scientists then analysed 600 million tweets, and found that depressive language – words such as “alone,” “bleak” and “trapped” – also increased during hot spells. “Surprisingly, these effects differ very little based on how rich populations are or if they are used to warm weather,” said Marshall Burke, of Stanford University. Nor did rising income levels or the adoption of air conditioning alter the pattern. “Hotter temperatures are clearly not the only, nor the most important, risk factor for suicide,” he stressed. “But our findings suggest that warming can have a surprisingly large impact on suicide risk.”

The iceman’s hearty last meal Twenty-six years after he was found entombed in ice in the South Tyrol – and 5,300 after his brutal death – researchers have discovered what Ötzi ate for his last meal. Although the Copper Age man’s shrivelled form had been examined in minute detail, for years his stomach eluded the researchers. Using new radiographic scans, they finally found it in 2009, pushed under his ribs – and it was full. Now, using a range of tests, they have worked out what is in it. It seems that on the day he died, Ötzi ate a well-thought-out meal for a hunter in a freezing climate, consisting of ibex meat and adipose fat, red deer and einkorn wheat, as well as traces of toxic bracken. It’s possible Ötzi ate the fern to treat stomach problems caused by parasites found in his gut, but it’s thought more likely he wrapped his meat in the leaves, and ingested the spores by accident.