This energy, which is a measure for the interplay between intensity and frequency of high and low pressure systems in the atmosphere, dropped by roughly one tenth since 1979. (sciencedaily.com)
This thinner ice was more prone to be broken up and melted by weather events, such as the strong low pressure system just mentioned. (dotearth.blogs.nytimes.com)
There have been fewer low pressure systems, more prevalent high pressure systems and, since 2000, the rainfall associated with each system has decreased. (jennifermarohasy.com)