A. Menzel et al., European phenological response to climate change matches the warming pattern. Glob. Change Biol. 12, 1969 (2006). doi:10.1111/j.1365-2486.2006.01193.x
The authors examined how changes in climate have influenced the timing of periodic life cycle events, such as leaves unfolding and fruit ripening. They analyzed a large set of data for European plants and a few animals, over the years 1971 to 2000.
They found that spring and summer life cycle events were happening earlier in the year and that these changes matched the patterns of climate warming.