Lakes and ice

Water is special: when it freezes, it becomes lighter than it was as a liquid. That is why ice floats on top and a lake freezes from the surface down. But how fast and how strongly the ice grows depends on many things: the cold of recent days and nights, the wind, currents in the water, springs on the bottom and plants growing through the ice.

Snow on the ice acts like a blanket. It insulates and slows the growth of the ice beneath, while its weight presses on the surface. Where streams flow in or out, at reeds, jetties and bridge piers, the ice often stays thinner. Thaws make ice rotten even when it still looks thick. You usually cannot see any of this from above – which is why this text deliberately gives no ice thickness as a rule of thumb.

Anyone who falls into cold water first experiences cold shock: uncontrolled gasping and rapid breathing. That is dangerous if your head is under water at the time. After a short while this reflex eases. Then there is a limited period in which your arms and hands still work well, before the cold weakens the muscles. Self-rescue has to succeed in that time.

The most important decision is made on the shore: has the ice been opened? Many councils officially open ice areas or close them with signs. Without that approval you stay off – no matter how cold the last few days were, how many people are already on the ice or how solid it feels at the edge. Flowing water is especially unpredictable; ice there is almost never reliable.

Even on approved ice it pays to be alert. Keep away from inlets and outlets, reeds, jetties and dark or wet patches. Do not walk bunched together as a group, because that concentrates the weight on a small area. Some people who are regularly out on ice wear ice picks around their neck – two handles with spikes that make it easier to pull yourself out of the water onto the slippery ice.

For an emergency, remember four steps. First: calm your breathing, keep your head above water and do not fight wildly straight away. Second: turn towards the side you came from – the ice held you there a moment ago. Third: spread your arms far onto the ice, kick your legs until your body is horizontal and slide yourself out flat. Fourth: do not stand up, but roll or crawl away until you are on safe ground.

When someone else falls through, the strongest impulse is to run after them. That is exactly what often puts the helper in the water too. Stay on the shore or on safe ground, call the local emergency number (112 in the EU) and reach or throw something: a long branch, a rope, a ladder, a scarf or a jacket. Talk to the person loudly and calmly, encourage them to hold on and tell them what to do. Rescue out on the ice itself is a job for trained rescuers.

Anyone who has been in icy water needs medical help afterwards, even if they feel fine again. Hypothermia can show up with a delay. Until help arrives, shield the person from wind, replace wet clothing with dry clothing if possible or wrap them up warmly, and get them into a warm room.

Dogs love running onto ice. Do not let them off the lead by frozen water. If a dog falls through, the same applies as with people: do not go after it, call emergency services and call the dog from the shore. Fire services help with animals in the ice too.

You often hear that you can judge ice by its colour, or that it is safe after a certain number of cold days. Such rules of thumb give false security. Ice can hold in one spot and break a few metres further on. The most reliable information is the official approval on site.

The British lifeboat charity RNLI describes with “Float to Live” that cold shock passes after a short time and that you should stay as calm as possible until then. This idea also helps when falling through ice: breathe first, then act.

With children it is worth discussing the rules before winter: never go to the ice alone, only onto approved areas, and if someone falls through, never go after them but shout for help. Children who know these sentences often act more safely in an emergency than adults deciding on the spur of the moment.