The only uncertainty concerns their scale. 只是不确定规模

406. As the seas rise, salt will invade the water table,
     随着海平面上升 盐水会侵入地下水
407. Depriving inhabitants of drinking water.
     减少居民的饮用水资源
408. Migratory phenomena are inevitable.
     人口迁移的现象将不可避免
409. The only uncertainty concerns their scale.
     只是不确定规模
410. In Africa, mount Kilimanjaro is unrecognizable.
     在非洲 乞力马扎罗山无法辨认
411. Eighty percent of its glaciers have disappeared.
     其80%的冰峰已经消失
412. In summer, the rivers no longer flow.
     夏天的时候 河水将会枯竭

来自《家园 第二部分 Home Part2》第 409 行