It is so cold that the ground is constantly frozen. 由于天气寒冷形成了冻土层

443. The clock of climate change is ticking
     在这片壮丽的土地上
444. in these magnificent landscapes.
     气候变化的时钟滴答作响
445. Here in Siberia and elsewhere across the globe,
     在西伯利亚 和一些其他的地方
446. It is so cold that the ground is constantly frozen.
     由于天气寒冷形成了冻土层
447. It's known as permafrost.
     这些都是永久冻土层
448. Under its surface lies a climatic time bomb: Methane,
     其表面下埋藏着一种气候定时炸♥弹♥ 甲烷
449. A greenhouse gas 20 times more powerful than carbon dioxide.
     一种比二氧化碳厉害20倍的温室气体

来自《家园 第二部分 Home Part2》第 446 行