In a survival scenario, this skill may come in handy. With a bit of practice and patience you can make a lens to start a fire from ice. Weather variables may come against you, you need as less wind as possible and the sun to make it work. The bigger the lens are, the faster will start a fire. Also small ice lens tend to melt very fast and that can be a problem. Enjoy the video!
Other Survival Solutions(This are the most reliable survival books that you can find)