A trip to Watchtree: Why won't this snowman melt?

We went to Watchtree Nature Reserve. This snowman was still almost a metre high. It occurred to think about the Physics behind its failure to melt away. What is it about putting the snow into a shape like this that makes it take longer to melt? First observation is that you compact the snow and compacted snow always seems to take longer to melt. To compact it, you squeeze the air out. Could that help? The thermal energy that melts the snow must be coming from the air on a day like today when the Sun is not out. The air is warmer than the snow so there is a temperature gradient. Maybe lack of air spaces stops warmer air circulating. But air filled snow is supposed to be a good insulator. Also putting the snow together in a big block reduces the surface area and thermal energy can only get in through the surface. I think this is likely to be the biggest factor but I will think more about it. Frustrating not to be able to explain such a simple thing.