Changes in North American spring

Onset of the growing season in mid-latitudes is a period of rapid transition, which includes heightened interaction between living organisms and the lower atmosphere. Phenological events (seasonal plant and animal activity driven by environmental factors), such as first leaf appearance or flower bloom in plants, can serve as convenient markers to monitor the progression of this yearly shift, and assess longer-term change resulting from climate variations. We examined spring seasons across North America over the 1900–1997 period using modelled and actual lilac phenological data. Regional differences were detected, as well as an average 5–6 day advance toward earlier springs, over a 35-year period from 1959–1993. Driven by seasonally warmer temperatures, this modification agrees with earlier bird nesting times, and corresponds to a comparable advance of spring plant phenology described in Europe. These results also align with trends towards longer growing seasons, reported by recent carbon dioxide and satellite studies. North American spring warming is strongest regionally in the northwest and northeast portions. Meanwhile, slight autumn cooling is apparent in the central USA. Copyright © 2000 Royal Meteorological Society

[1]  Mark D. Schwartz,et al.  Surface phenology and satellite sensor-derived onset of greenness: an initial comparison , 1999 .

[2]  John E. Walsh,et al.  Recent Variations of Sea Ice and Air Temperature in High Latitudes , 1993 .

[3]  Mark D. Schwartz,et al.  Young students, satellites aid understanding of climate-biosphere link , 2000 .

[4]  Annette Menzel,et al.  Growing season extended in Europe , 1999, Nature.

[5]  T. Sparks,et al.  The times they are a-changing? , 1999, Bird Conservation International.

[6]  S. Running,et al.  Generalization of a forest ecosystem process model for other biomes, Biome-BGC, and an application for global-scale models. Scaling processes between leaf and landscape levels , 1993 .

[7]  C. D. Keeling,et al.  Increased activity of northern vegetation inferred from atmospheric CO2 measurements , 1996, Nature.

[8]  M. D. Schwartz.  Advancing to full bloom: planning phenological research for the 21st century , 1999 .

[9]  C. Tucker,et al.  Increased plant growth in the northern high latitudes from 1981 to 1991 , 1997, Nature.

[10]  Mark D. Schwartz,et al.  Monitoring global change with phenology: The case of the spring green wave , 1994 .

[11]  Ellen J. Cooter,et al.  Recent frost date trends in the north‐eastern USA , 1995 .

[12]  D. Winkler,et al.  Climate change has affected the breeding date of tree swallows throughout North America , 1999, Proceedings of the Royal Society of London. Series B: Biological Sciences.

[13]  Mark D. Schwartz,et al.  Green-wave phenology , 1998, Nature.