«That downward trend reflects Arctic climate change, but the causes of yearly variations around the trend are harder to pin down,» said Lawrence Hamilton, co-author and a researcher at the University of New Hampshire. (sciencedaily.com)
Those natural yearly variations led to the occasional drought, but the long - term drying exacerbated the 2007 - 2010 drought, making it the most severe in the observed record, says Kelley. (newscientist.com)
In contrast, on decadal and even yearly variations in pH are up to ten times larger than the overall 200 - year trend (the red trend line). (notrickszone.com)