New Scientist: Though scientists tend to agree that summer ice at the North Pole will eventually disappear, they haven’t settled on a date. And one group now claims to have evidence that Santa may have to start swimming much sooner than we thought. US researchers claim to have found evidence that accelerated melting has crossed a “tipping point” from which there is no going back. The amount of summer ice at the North Pole has steadily declined since 1979, according to satellite images. …