Anders Tysk is in charge of the annual Ice-Skating race Vikingarännet here in Stockholm, and is an ice expert. He tells Radio Sweden that the ice on Sweden's lakes is currently a mix of old and new ice, with the old ice often having an insulating layer of snow on it, making it weak and fragile.
He says that skaters and walkers should wait at least until the middle of next week before daring out onto the lakes, by then the temperatures of -15 should have made the ice thick enough for humans to walk on, if there isn't too much snow. Just two cm of snow reduces ice growth by 90 percent he says.
Otherwise, anyone making their way onto the ice should make sure they have ice sticks with them to test the ice, as well as ice prods which can help you pull yourself out of the water. A backpack with a change of clothes is always good, he adds, as it can also act as a lifejacket and keep you higher in the water should you fall in.
If you see someone fall through the ice, the most important thing to do is to call 112, and summon the emergency services. Only try to help yourself if you have good knowledge of the ice, and a ladder or line handy, Anders Tysk says.