The Energetics Will Kill Them Off

Animal behaviour is always a costs versus benefits calculation (animals generally only perform activities, when the benefits outweigh the costs). It has been estimated that the loss of Arctic ice, now requires Polar bears to use four times the energy that was formerly required just to survive (https://www.theguardian.com/world/2021/feb/24/arctic-ice-loss-forces-polar-bears-to-use-four-times-as-much-energy-to-survive-study). The extra energy required by Polar bears, will reduce their fat stores for hibernation, leave less energy for moving and rearing cubs etc. It is very likely that this extra energy requirement (especially, as it will be seen over an extended period), will make this animal's life-style completely untenable. In fact, most Arctic predators (including Narwhals) will find it impossible to survive in an Arctic that can be largely ice-free in locations for many days.