Figure 1.7. Plotted are the frequencies of the correlation coefficients (associations) between the timing of changes in traits (e.g., earlier egg-laying) of 145 species and modelled (HadCM3) spring temperatures for the grid-boxes in which each species was examined. At each location, all of which are in the Northern Hemisphere, the changing trait is compared with modelled temperatures driven by: (a) natural forcings (purple bars), (b) anthropogenic (i.e., human) forcings (orange bars), and (c) combined natural and anthropogenic forcings (yellow bars). In addition, on each panel the frequencies of the correlation coefficients between the actual temperatures recorded during each study and changes in the traits of 83 species, the only ones of the 145 with reported local-temperature trends, are shown (dark blue bars). On average the number of years that species were examined is about 28, with average starting and ending years of 1960 and 1998. Note that the agreement: (a) between the natural and actual plots is weaker (K = 60.16) than (b) between the anthropogenic and actual (K = 35.15), which in turn is weaker than( c) the agreement between combined and actual (K = 3.65). Taken together, these plots show that a measurable portion of the warming regional temperatures to which species are reacting can be attributed to humans, therefore showing joint attribution (after Root et al., 2005).