Scientists have noted significant changes reflected in monitoring data gathered over the last several decades. The average August surface water temperature has increased up to 6.8°F (3.8°C) in Lake Champlain since monitoring began in 1964. Lake Champlain has frozen over less frequently in the last 50 years than it did in the previous 130-year period. From 1976 to 2005, the average air temperature in the region increased by 2.2°F (1.2°C).
Precipitation also is trending upward; the average annual precipitation over the past 40 years was three inches greater than that of the previous 80-year period. These increases correspond to similar data throughout the Northeastern United States and Great Lakes regions. The timing and intensity of precipitation events are also changing. During summer, the number of rainfall events is declining but the intensity of these storms is increasing.
Climate change outcomes based on predicted emission scenarios suggest a compelling need for policies that reduce regional and global emissions of greenhouse gases. Some scenarios predict that, within 60 years, the Lake Champlain region’s climate will be comparable to that of Pennsylvania or Virginia’s current climate if no immediate action is taken to reduce greenhouse gas emissions. Compared to the Lake Champlain Basin, Pennsylvania and Virginia have shorter winters with less snowfall and more humid summers with more frequent storm events.