Fig. 1 Leaf out pictures taken by scientists monitoring leafing in a traditional on-the-ground study (taken by Richard B. Primack at the Arnold Arboretum in Boston, Massachusetts USA)

Fig. 2 A graph showing the growth of the leaf canopy over a growing seasons using satellite data from a location in New England, in the northeastern United States. The vegetation data is fit to logistic growth sigmoid functions and the onset and offset of greenness are calculated at the half-maxima of the curve. The quality of the data points is indicated by the symbol shading, with black diamonds having the least error and white diamonds having the most error. Figure from Fisher et al., 2006).

Fig. 3 A sequence of photos taken over a three week period in the spring of 2011 showing the development of the leaf canopy at Minute Man National Historical Site, a park in Concord, Massachusetts (Photos by Richard B. Primack)

Fig. 4 A hillside in the northeastern United States showing the effects of a late frost following a period of warming. Trees that responded more quickly to warm temperatures, such as sugar maples, suffered damage to early leaves, while more conservative leafing species, such as American beech, fared better and are developing normally. Figure from (Hufkens et al., 2012b).

Fig. 5 Leaf out pictures taken at the Arnold Arboretum in Boston, Massachusetts USA by scientists monitoring leafing in a traditional on-the-ground study (taken by Dr. Richard B. Primack)

Fig. 6 A graph showing the growth of the leaf canopy over a growing season using satellite data from a location in New England, in the northeastern United States. The vegetation data is fit to logistic growth sigmoid functions and the onset and offset of greenness are calculated at the half-maxima of the curve. The quality of the data points is indicated by the symbol shading, with black diamonds having the least error and white diamonds having the most error (Figure from Fisher et al., 2006).

Fig. 7 A sequence of photos taken over a three week period in the spring of 2011 showing the development of the leaf canopy at Minute Man National Historical Site, a park in Concord, Massachusetts, with a bridge, a monument, and statue as points of reference. The leaf out times of individual trees can be seen in these photos. Photos by Richard B. Primack.

Fig. 8 A hillside in the northeastern United States showing the effects of a late frost following a period of warming. Trees that responded more quickly to warm temperatures, such as sugar maples, suffered damage to early leaves, while more conservative leafing species, such as American beech, fared better and are developing normally. Figure from (Hufkens et al., 2012b)