【正确答案】 1、they are dumping considerably more fresh water    

【答案解析】在文章的最后一部分：“Researchers using ice-penetrating radar also found that the glaciers are on average 430 meters thicker than previously thought，meaning they are dumping considerably more fresh water into the ocean．”冰山要比以前估计的厚430米，这意味着会有更多的淡水注入海洋。