I have found that all the children under 9 that I know that have watched this found it quite a scary and emotional movie (not horror scary or anything). There is a scene where a leopard seal (looks like a leopard seal, anyway) jumps out of (or behind?) of a whale carcass, scaring the dogs. It attacks a dog.
Another time, a dog emotionally dies in cold weather, while his friends leave him. The dogs escape from chains, but being too weak, the dying dog goes to sleep on the ice, but later dies.
Another dog dies after falling off embankment.
Both emotional and potentially frightening deaths.
A man gets frostbite and black fingers, another is cold and falls into freezing antarctic water, through ice. He survives, shows no injury but is taken to hospital.
Otherwise suitable for children, but still maybe watch it first to check how you think it will be, as children differ in needs...