题目选项分析

According to scientists at the University of Alaska, while the surface temperature of the globe has risen over the last century by about one degree Fahrenheit, it had increased in Alaska, Siberia, and northwestern Canada by about five degrees over the previous thirty years.

According to scientists at the University of Alaska, while the surface temperature of the globe has risen over the last century by about one degree Fahrenheit, the surface temperature in Alaska, Siberia, and northwestern Canada has increased over the last thirty years by about five degrees.