And Iris Stewart,a climate researcher at the University of California,San Diego,has found that in the last 50 years,run-off peaks in the western US and Canada have been happening earlier and earlier.

• 一位来自圣迭哥加利福尼亚大学，名叫艾里斯·斯图尔特的气象学者发现在最近50年里，美国西部和加拿大的径流峰值到来的时间越来越早。