In phenology, season creep is a neologism that refers to observed changes in the timing of the seasons,[1][2] especially earlier indications of spring[3] widely observed in temperate areas across the Northern Hemisphere.[4] [5] Phenological records analyzed by climate scientists have shown significant temporal trends in the observed time of seasonal events,[6][7] from the end of the 20th century and continuing into the 21st century.[5][8] In Europe, season creep has been associated with the arrival of spring moving up by approximately one week in a recent 30 year period.[9][10] Other studies have put the rate of season creep measured by plant phenology in the range of 2–3 days per decade advancement in spring, and 0.3–1.6 days per decade delay in autumn, over the past 30–80 years.[11]

Observable changes in nature related to season creep include birds laying their eggs earlier and buds appearing on some trees in late winter.[12] In addition to advanced budding, flowering trees have been blooming earlier, for example the culturally important cherry blossoms in Japan,[13][14] and Washington, D.C.[15] Northern hardwood trees have been trending toward leafing out sooner, and retaining their green canopies longer.[16]

The effects of season creep have been noted by non-scientists as well, including gardeners who have advanced their spring planting times,[17] and experimented with plantings of less hardy warmer climate varieties of non-native plants.[18] While summer growing seasons are expanding, winters are getting warmer and shorter, resulting in reduced winter ice cover on bodies of water,[19] earlier ice-out,[20] earlier melt water flows,[21] and earlier spring lake level peaks.[22] Some spring events, or "phenophases", have become intermittent or unobservable; for example, bodies of water that once froze regularly most winters now freeze less frequently,[8][23][24] and formerly migratory birds are now seen year-round in some areas.[25]

Relationship to global warmingEdit

The full impact of global warming is forecast to happen in the future, but climate scientists have cited season creep as an easily observable effect of climate change that has already occurred.[5][12] A large systematic phenological examination of data on 542 plant species in 21 European countries from 1971–2000 showed that 78% of all leafing, flowering, and fruiting records advanced while only 3% were significantly delayed, and these observations were consistent with measurements of observed warming.[10][26] Similar changes in the phenology of plants and animals are occurring across marine, freshwater, and terrestrial groups studied, and these changes are also consistent with the expected impact of global warming.[27] While phenology fairly consistently points to an earlier spring across temperate regions of North America, a recent comprehensive study of the sub-arctic showed greater variability in the timing of green-up, with some areas advancing, and some having no discernible trend over a recent 44-year period.[28]


Season creep was included in the 9th edition of the Collins English Dictionary published in London June 4, 2007.[29][30] The term was popularized in the media after the report titled "Season Creep: How Global Warming Is Already Affecting The World Around Us" was published by the American environmental organization Clear the Air on March 21, 2006.[31] In the "Season Creep" report, Jonathan Banks, Policy Director for Clear the Air, introduced the term as follows:

While to some, an early arrival of spring may sound good, an imbalance in the ecosystem can wreak havoc. Natural processes like flowers blooming, birds nesting, insects emerging, and ice melting are triggered in large part by temperature. As temperatures increase globally, the delicately balanced system begins to fall into ecological disarray. We call this season creep.[31]

Other usesEdit

The term "season creep" has been applied in other contexts as well:


  1. Gabay, Jonathan (2006). "23. So What's New?". Gabay's Copywriters' Compendium (Second Edition: The Definitive Professional Writers Guide ed.). Oxford: Butterworth-Heinemann. pp. p. 701. ISBN 0-7506-8320-1. "Season creep n. Earlier spring weather and other gradual seasonal shifts caused by global climate change.". 
  2. 2.0 2.1 Maxwell, Kerry (2006-09-18). "Macmillan English Dictionary Word Of The Week Archive - "Christmas creep"". New Words. Macmillan Publishers. Retrieved on 2007-12-26. "…season creep, earlier spring weather and seasonal shifts caused by global climate change"
  3. Maxwell, Kerry (2007-12). "A review of 2007 in twelve words". MED Magazine. Macmillan English Dictionaries. Retrieved on 2007-12-23. "It’s a classic case of the newly-identified phenomenon of season creep, where Winters are warmer and Spring arrives earlier."
  4. Schwartz, M. D.; Ahas, R.; Aasa, A. (2006). "Onset of spring starting earlier across the Northern Hemisphere". Global Change Biology 12 (2): 343–351. doi:10.1111/j.1365-2486.2005.01097.x. "SI first leaf dates, measuring change in the start of ‘early spring’ (roughly the time of shrub budburst and lawn first greening), are getting earlier in nearly all parts of the Northern Hemisphere. The average rate of change over the 1955–2002 period is approximately -1.2 days per decade.". 
  5. 5.0 5.1 5.2 Cleland, E.E.; Chiariello, N.R.; Loarie, S.R.; Mooney, H.A.; Field, C.B. (2006). "Diverse responses of phenology to global changes in a grassland ecosystem". Proceedings of the National Academy of Sciences 103 (37): 13740. doi:10.1073/pnas.0600815103. PMID 16954189. "Shifting plant phenology (i.e., timing of flowering and other developmental events) in recent decades establishes that species and ecosystems are already responding to global environmental change. Earlier flowering and an extended period of active plant growth across much of the northern hemisphere have been interpreted as responses to warming.". 
  6. McFedries, Paul (2006-08). "Changing Climate, Changing Language". IEEE Spectrum. Retrieved on 2007-12-23. "Did spring seem to arrive a bit earlier than usual this year in your part of the world? That wouldn’t be surprising, because we seem to be undergoing season creep: earlier spring weather and other gradual seasonal shifts, particularly those caused by global climate change."
  7. Sayre, Carolyn (2006-12-17). "The Year in Buzzwords 2006". TIME. Retrieved on 2007-12-26. "SEASON CREEP n. Spring seemed to come early this year--and summer lasted a bit longer. What's to blame? Most scientists say global warming."
  8. 8.0 8.1 Skinner, Victor (2007-02-17). "Area temperatures expected to rise back to 'normal'". Traverse City Record-Eagle. Retrieved on 2007-12-27. "...the west arm of Grand Traverse Bay ... has only frozen over five times since 1987,.... Between 1851 and 1980, [it] froze at least seven years per decade, ... the bay-freezing trend shows "a long-term gradual decline with a significant decline in the past 25 to 35 years.”"
  9. Stutz, Bruce (2006-04-21). "Suddenly spring". The Record (Bergen County, NJ). Archived from the original on 2013-01-25. Retrieved on 2007-12-23. "In fact, due to global warming, spring across the Northern Hemisphere arrives a week or more earlier than it did 30 years ago, a phenomenon starting to be known as "season creep.""
  10. 10.0 10.1 "Climate changes shift springtime : A Europe-wide study has provided "conclusive proof" that the seasons are changing, with spring arriving earlier each year, researchers say.". Science/Nature. BBC NEWS (2006-08-25). Retrieved on 2007-12-28. "Spring was beginning on average six to eight days earlier than it did 30 years ago, the researchers said."
  11. Sherry, R.A.; Zhou, X.; Gu, S.; Arnone Iii, J.A.; Schimel, D.S.; Verburg, P.S.; Wallace, L.L.; Luo, Y. (2007). "Divergence of reproductive phenology under climate warming". Proceedings of the National Academy of Sciences 104 (1): 198. doi:10.1073/pnas.0605642104. PMID 17182748, Retrieved on 29 December 2007. "Phenology is a sensitive biosphere indicator of climate change. Long-term surface data and remote sensing measurements indicate that plant phenology has been advanced by 2–3 days in spring and delayed by 0.3–1.6 days in autumn per decade in the past 30–80 years, resulting in extension of the growing season.". 
  12. 12.0 12.1 "Man bags at ten paces? Just look it up". News (2007-06-04). Retrieved on 2007-12-23. "While the full impact of global warming is still to be experienced, many scientists are warning that it is responsible for earlier springs leading to longer summers."
  13. Miller-rushing, A.J.; Katsuki, T.; Primack, R.B.; Ishii, Y.; Lee, S.D.; Higuchi, H. (2007). "Impact of global warming on a group of related species and their hybrids: cherry tree (Rosaceae) flowering at Mt. Takao, Japan". American Journal of Botany 94 (9): 1470. doi:10.3732/ajb.94.9.1470, Retrieved on 29 December 2007. "We examined a 25-yr record (1981–2005) of flowering times for 97 trees, representing 17 species and hybrids of cherry (Cerasus sp. or Prunus sp.) grown at Mt. Takao, in Tokyo, Japan. The cherry trees flowered earlier over time, by an average of 5.5 d over the 25-yr study.". 
  14. Cleland, E.E.; Chuine, I.; Menzel, A.; Mooney, H.A.; Schwartz, M.D. (2007). "Shifting plant phenology in response to global change". Trends in Ecology & Evolution 22 (7): 357–365. doi:10.1016/j.tree.2007.04.003, Retrieved on 29 December 2007. "The longest and best known phenological records come from the Far East and Europe, including ... the 1300+-year Kyoto cherry blossom time series [37]... These longterm historical records can serve as proxies for temperature where thermometer data are unavailable.". 
  15. Peterson, Paul M.; Stanwyn G. Shetler, Mones S. Abu-Asab, Sylvia S. Orli (2005). "Chapter 8 Global Climate Change: The Spring Temperate Flora". in Krupnick, Gary A; W. John Kress. Plant conservation: a natural history approach. Chicago: University of Chicago Press. pp. p. 192. ISBN 0-226-45513-0. "Finally, there is the Cherry Blossom Festival in Washington, DC, each spring. On average the two principal species, Prunus serrulata (Kwanzan cherry and other varieties) and P. X yedoensis ( Yoshino cherry), bloom six and nine days earlier, respectively, than they did in 1970.". 
  16. Richardson, A.D.; Bailey, A.S.; Denny, E.G.; Martin, C.W.; O'Keefe, J. (2006). "Phenology of a northern hardwood forest canopy". Global Change Biology 12 (7): 1174–1188. doi:10.1111/j. "…significant trends (P≤0.05) towards an earlier spring (e.g. sugar maple, rate of change=0.18 days earlier/yr), consistent with other studies documenting measurable climate change effects on the onset of spring in both North America and Europe. Our results also suggest that green canopy duration has increased by about 10 days (e.g. sugar maple, rate of change=0.21 days longer/yr) over the period of study.". 
  17. Smith, Virginia A. (2007-04-07). "Out on a limb: Gardeners excited by the early warmth - call it "season creep" - are experimenting with earlier planting and new varieties.". The Philadelphia Inquirer. Retrieved on 2007-12-23. "…earlier springs — an idea known as "season creep" — may or may not be related to long-term warming trends. Yet the reality of year-to-year weather weirdness recently, coupled with the ever-present impulse to outsmart Mother Nature, has prompted more than a few gardeners to shun conventional horticultural wisdom."
  18. Williams, Brad (2007-04-08). "Dogwoods to frogs, tulips to snow, Knox shows signs of warming". Knoxville News Sentinel. Retrieved on 2007-12-23. "Knoxville is now in hardiness Zone 7, a zone where more southern trees and shrubs flourish. The zone shift can be seen all across the northern half of the state. It effectively means plants that once had difficulty growing here are now finding it easier to thrive, said Lisa Stanley, master gardener at Stanley's Greenhouses"
  19. Magnuson, J.J.; Robertson, D.M.; Benson, B.J.; Wynne, R.H.; Livingstone, D.M.; Arai, T.; Assel, R.A.; Barry, R.G.; Card, V.; Kuusisto, E.; Others, (2000). "Historical Trends in Lake and River Ice Cover in the Northern Hemisphere". Science 289 (5485): 1743–1746. doi:10.1126/science.289.5485.1743. PMID 10976066, Retrieved on 28 December 2007. "Freeze and breakup dates of ice on lakes and rivers provide consistent evidence of later freezing and earlier breakup around the Northern Hemisphere from 1846 to 1995. Over these 150 years, changes in freeze dates averaged 5.8 days per 100 years later, and changes in breakup dates averaged 6.5 days per 100 years earlier;". 
  20. Hodgkins, G.A.; Ii, I.C.J.; Huntington, T.G. (2002). "Historical Changes In Lake Ice-out Dates As Indicators Of Climate Change In New England, 1850--2000". Int. J. Climatol 22: 1819–1827. doi:10.1002/joc.857, Retrieved on 28 December 2007. "Various studies have shown that changes over time in spring ice-out dates can be used as indicators of climate change.… Ice-out dates have become significantly earlier in New England since the 1800s". 
  21. Dybas, Cheryl Lyn (2006-03-20). "Early Spring Disturbing Life on Northern Rivers". The Washington Post. Retrieved on 2007-12-26. "Research by [USGS hydrologist Glenn] Hodgkins and USGS scientist Robert Dudley also shows changes in early-spring stream flow across eastern North America from Minnesota to Newfoundland. Rivers are gushing with snow- and ice-melt as much as 10 to 15 days sooner than they did 50 to 90 years ago, based on USGS records."
  22. "Early risers". New Scientist 167 (2241): 21. 2000-06-03, Retrieved on 27 December 2007. "North America's Great Lakes are reaching their spring high-water levels a month earlier than they did when records began in 1860. Levels normally rise in the spring as snow melts, but regional temperatures have been rising for the past 90 years, and winter ice cover has been shrinking.". 
  23. Wake, Cameron (2006-12-04). "Climate Change in the Northeast: Past, Present, and Future" (pdf). Climate Change in the Hudson Valley, NY. Retrieved on 2007-12-27. "A particularly interesting lake ice record comes from Lake Champlain where they record the ice in date.… Of more significance is the fact that the ice has not frozen in the area of observation in 16 of the past 30 years."
  24. "Why Less Winter Ice is the Pitts for State". The Detroit Free Press (2006-04-03). Retrieved on 2007-12-23. "Grand Traverse Bay … froze at least seven winters out of every 10; the rate slipped in the 1980s. In the 1990s, the bay froze only three times. So far this decade, once. Observers see that as one more sign of what some call "season creep," or evidence of global warming."
  25. "Report warns of global warming increase". Portsmouth Herald. Retrieved on 2007-12-27. "…Jan Pendlebury, executive director of the New Hampshire chapter of the National Environmental Trust, said… 'Global warming is forcing changes to the quintessential indicator that spring has arrived: return of the robin. Recent years have documentation that rather than flying south with other feathered friends, many populations of robins are becoming year-round residents, not only in the southern tier of the state, but as far north as Jackson.'"
  26. Menzel, A.; Sparks, T.H.; Estrella, N.; Koch, E.; Aasa, A.; Ahas, R.; Alm-kübler, K.; Bissolli, P.; Braslavská, O.; Briede, A.; Others, (2006). "European phenological response to climate change matches the warming pattern". Global Change Biology 12 (10): 1969–1976. doi:10.1111/j.1365-2486.2006.01193.x. "Our results showed that 78% of all leafing, flowering and fruiting records advanced (30% significantly) and only 3% were significantly delayed, whereas the signal of leaf colouring/fall is ambiguous.". 
  27. Parmesan, C. (2006). "Ecological and evolutionary responses to recent climate change". Annu. Rev. Ecol. Evol. Syst 37: 637–69. doi:10.1146/annurev.ecolsys.37.091305.110100. "Ecological changes in the phenology and distribution of plants and animals are occurring in all well-studied marine, freshwater, and terrestrial groups. These observed changes are heavily biased in the directions predicted from global warming…". 
  28. Delbart, N.; Picard, G.; Kergoat, L.; Letoan, T.; Quegan, S.; Dye, D.; Woodward, I.; Fedotova, V. (2007). Spring phenology in taiga and tundra, Retrieved on 29 December 2007. "The model was applied over the whole low arctic region from 1958 to 2002. In North East Canada and North East Russia, no remarkable trend is found in the timing of green- up, whereas a ten day advance is recorded in the last few decades in North Alaska and in North West Siberia.". 
  29. Topping , Alexandra (2007-06-04). "'Hoodies', 'size zero', 'man flu', make it into the dictionary". The Guardian. Retrieved on 2007-12-23. "A preoccupation with environmental issues, a favourite topic of [British Conservative Party leader David] Cameron's, is also reflected in new phrases such as "carbon footprint", "carbon offsetting" and "season creep", used to describe the changing length of the seasons thought to be caused by climate change."
  30. "'Season creep', 'BBQ stopper' appear in dictionary pages", ABC News Online (2007-06-04). Retrieved on 23 December 2007. Archived from the original on 6 June 2007. ""Hoodies", "season creep" and "barbecue stopper" are among hundreds of new words and phrases included in an updated version of an English dictionary." 
  31. 31.0 31.1 "Season creep". Word Spy. Retrieved on 2007-12-23. "Earliest Citation:… Jonathan Banks, 'Season Creep: How Global Warming Is Already Affecting The World Around Us,' National Environment Trust, March 21, 2006"
  32. "What Has Longer Season Brought To Baseball Besides Snow Warnings?". Seattle Post-Intelligencer (Seattle, WA) (1997-10-23). Archived from the original on 2013-01-25. Retrieved on 2007-12-26. "Call it season creep. First came the shift to 162 games, a change that made it, among other things, impossible to compare Roger Maris' 61 home runs to Babe Ruth's 60."
  33. "Virginian-Pilot Archives". The Virginian-Pilot. Pilot Media (2007-05-29). Retrieved on 2007-12-26. "'Season creep' has expanded the time an intercollegiate athlete must devote to his or her specialty. No sport should be year-round or nearly so."
  34. Sellnow, Greg (2007-04-07). ", Greg Sellnow column: I'm just sayin'.". Post-Bulletin, Rochester, Minn.. Retrieved on 2007-12-26. "And it is money, of course, that is responsible for campaign season creep. If you don't raise money early -- gobs and gobs of it -- you'll find yourself on the fundraising super highway with roller marks over your body, where your opponent's war chest plowed over you."
  35. Siewers, Alf (1987-11-25). "He's well-suited to enjoying life of Santa". Chicago Sun-Times. Retrieved on 2007-12-26. "And so does the culture, with a commercializing of himself that Santa deplores even as he has watched the holiday season creep back to Labor Day."