国家地理:不再冻人的五大湖(4)（在线收听）

In Japan, priests at a Shinto temple have kept an almost 600-year record of when their lake freezes all the way across. Natural climate cycles emerge from that record -- dwarfed in recent decades by the human-caused warming that has gripped the planet. Merchants who used Finland's Tornio River for trade tracked the date the ice broke up each year from 1693 onward.

日本一座神道教寺庙里的僧侣们保存了一份将近600年的湖泊结冰记录资料。自然气候循环就是从这个记录中得出的，但是近几十年来，由于人类活动导致的全球变暖更显著，所以这种自然气候循环就显得微不足道了。从1693年开始，利用芬兰托尔尼奥河进行贸易的商人，每年都会跟踪冰层的破裂日期。

In Lake Superior, shipping companies have kept records of ice formation and breakup since 1857. The records show cold years with long stretches of early ice, warm years with less. But overall they are a clear signal of human-caused warming since the industrial revolution.

在苏必利尔湖，船运公司自1857年以来一直保存着冰层形成和破裂的记录资料。记录显示，寒冷的年份会有一个较长时间的早期冰期，而温暖的年份则相对较短。但总的来说，这是工业革命以来人为因素造成的气候变暖的明确信号。

"What's happening in the Great Lakes region is a small part of a bigger story," says Lesley Knoll. A lake expert at the University of Minnesota's Itasca Biological Station, she studies people's cultural relationships with frozen lakes.

莱斯利·诺尔表示：“五大湖地区正在发生的，只是一个大事件中的一小部分。”作为明尼苏达大学伊塔斯卡生物站的湖泊专家，她主要负责研究人类文化与冰冻湖泊的之间关系。