subsurface ice

例句：

1. 1. The subsurface ice is melting due to the warming temperatures.
   由于温度上升，地下冰正在融化。
2. 2.The glaciers are slowly retreating due to climate change.
   由于气候变化，冰川正在缓慢后退。
3. 3.The permafrost is a layer of frozen soil that remains at or below ground temperature for many years.
   永久冻土层是一层冻结的土壤，在地面温度以下多年保持不变。