It has just come through four months of rain, and it's now going into eight months of dry season.  刚刚经历了4个月的雨季，将要进入8个月的旱季。

　　And watch the change as it goes into this long dry season.  注意看草原进入漫长的旱季后的变化。

　　Now, all of that grass you see aboveground has to decay biologically before the next growing season,  你们看到的所有地表上的草,在下个生长季节到来之前,都会腐烂掉，

　　and if it doesn't, the grassland and the soil begin to die.  否则的话，草地和土壤就会开始死亡。

　　Now, if it does not decay biologically, it shifts to oxidation, which is a very slow process,  如果它不是生物性的腐烂，而是以氧化的形式腐烂，这是一个非常缓慢的过程，

　　and this smothers and kills grasses, leading to a shift to woody vegetation and bare soil, releasing carbon.  并且会消耗氧气，杀死草本植物，只有木本的植物才能生存，导致了地表被裸露，碳元素释放到大气层。

　　To prevent that, we have traditionally used fire.  为了防止这种情况，传统上我们是用火烧。

　　But fire also leaves the soil bare, releasing carbon, and worse than that, burning one hectare of grassland gives off more,  可是火也会让地表被裸露，碳元素释放到大气层，更糟糕的是，烧掉一公顷的草地所释放的有害污染物，

　　and more damaging, pollutants than 6,000 cars.  要比6000辆汽车排放的总和还要多。

　　And we are burning in Africa, every single year, more than one billion hectares of grasslands, and almost nobody is talking about it.  每年在非洲我们都会烧掉十亿公顷以上的草地，几乎没人关心过这个。

　　We justify the burning, as scientists, because it does remove the dead material and it allows the plants to grow. 作为科学家，我们理解烧草可以除掉死植物，允许植物成长。

　　Now, looking at this grassland of ours that has gone dry, what could we do to keep that healthy?  看看这片草地已经枯干，我们做什么才能保持健康？

　　And bear in mind, I'm talking of most of the world's land now. Okay?  记住，我讲的是世界上大部分的土地。明白么？

　　We cannot reduce animal numbers to rest it more without causing desertification and climate change.  我们不能用减少动物数量的方式让植被休养，因为这会引发土地荒漠化和气候变化。

　　We cannot burn it without causing desertification and climate change. 我们不能用焚烧的方法，这也会引发荒漠化和气候变化。

　　What are we going to do?  那我们能怎么办？

　　There is only one option, I'll repeat to you, only one option left to climatologists and scientists,  只有一种方案，我再重复一遍，唯一的一种方法摆在气候学家和科学家的面前，

　　and that is to do the unthinkable, and to use livestock, bunched and moving, as a proxy for former herds and predators, and mimic nature.  个方案非常的不可思议，就是使用牲畜，成群结队地迁移，把它们看作从前的游牧动物和捕食动物，模拟大自然的行为。

　　There is no other alternative left to mankind. 这这种方法是人类唯一的选择了。