Table 1.

Climate variable loadings from Zackenberg, Greenland (1996–2014) onto principal components. Main contributors for each principal component (greater than 0.50) are highlighted in boldface type. Temperatures include the average seasonal temperature for each summer of sampling and for each season over the previous year. Average temperature of the previous summer was log-transformed prior to PCA.

climate variable	warmer active seasons & fewer winter freeze–thaw events (PC1)	warmer non-active seasons (PC2)	longer winters (PC3)
average summer temperature	0.87	0.1	0.26
average temperature of previous summer	0.76	0.47	−0.03
winter freeze–thaw events	−0.69	0.17	−0.04
average temperature previous fall	0.67	0	−0.43
average spring temperature	−0.06	0.81	−0.35
average winter temperature	0.1	0.78	0.38
winter duration	0.06	−0.02	0.91
eigenvalue	2.27	1.52	1.35
% variation	0.32	0.22	0.19
cumulative % variation	0.32	0.54	0.73