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Plant phenology (CLIM 023) - Assessment published Sep 2008

Indicator Assessment Created 08 Sep 2008 Published 08 Sep 2008 Last modified 11 Sep 2012, 04:51 PM
Topics: ,

Update planned for November 2012

Generic metadata


Climate change Climate change (Primary topic)

pollen | plants | climate change | temperatures | flowering | leafing
DPSIR: Impact
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)
Indicator codes
  • CLIM 023
Temporal coverage:
1950-2005, 2008
Geographic coverage:
Austria, Belarus, Czech Republic, Estonia, Germany, Poland, Slovenia, Switzerland, Ukraine, United Kingdom

Key policy question:

Key messages

  • The timing of seasonal events in plants is changing across Europe, due mainly to changes in climate conditions; 78 % of leaf unfolding and flowering records show advancing trends and only 3 % a significant delay. Between 1971 and 2000, the average advance of spring and summer was 2.5 days per decade.
  • As a consequence of climate-induced changes in plant phenology, the pollen season starts on average 10 days earlier and is longer than 50 years ago.
  • Trends in seasonal events will continue to advance as climate warming increases in the years and decades to come.

Phenological sensitivity to temperature changes

Note: In a study of 254 national records across nine countries, most phenological changes correlated significantly with mean monthly temperatures of the previous two months

Data source:

Menzel, A.; Sparks, T. H.; Estrella, N.; Koch, E.; Aasa, A.; Ahas, R.; Alm-Kübler, K.; Bissolli, P.; Braslavská, O.; Briede, A.; Chmielewski, F. M.; Crepinsek, Z.; Curnel, Y.; Dahl, Å.; Defila, C.; Donelly, A.; Filella, I.; Jatczak, K.; Måge, F.; Mestre, A.; Nordli, Ø.; Peñuela, J.; Pirinen, P.; Remišová, V.; Scheinfinger, H.; Stríž, M.; Susnik, A.; Van Vliet, A. J. H.; Wiegolaski, F.-E.; Zach, S.; Zust, A., 2006. European phenological response to climate change matches the warming pattern. Global Change Biology 12: 19691976.

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Oak (Quercus sp) leafing date in Surrey (United Kingdom) 1950-2008

Note: Annual observations (connected by straight lines); black line: average change in leafing date (showing advancement).

Data source:

Nature's Calendar, UK. climate+change/past.htm.

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Key assessment

Past trends

There is clear evidence of changing phenology across Europe in recent decades (Parmesan and Yohe, 2003; Root et al., 2003; Menzel et al., 2006) (Figure 1). Overall, 62 % of the observed variability in the timing of life cycle events can be explained by climate (van Vliet, 2008).  However, variability differs between events, with those occurring earlier (i.e. spring) being more variable than later events (Menzel et al., 2006). For example:

78 % of all leaf unfolding, flowering and fruiting records across Europe show an advancing trend and only 3 % a significant delay. The average advance of spring/summer phenological events is occurring at a rate of 2.5 days per decade (Menzel et al., 2006).

The pollen season currently starts on average 10 days earlier and is of longer duration than 50 years ago.

In Britain, the first flowering date for 385 plant species has advanced by 4.5 days on average during the past decade in comparison with the previous four decades (Fitter and Fitter, 2002); oak leafing has advanced three weeks in the last 50 years (DEFRA, 2007) (Figure 2).

In the Arctic, rapid climate-induced advancement of spring phenomena (e.g. flowering, egg laying) has been observed during the last 10 years. The strong responses of Arctic ecosystems and large variability within species illustrate how easily biological interactions can be disrupted by climate change (Høye et al., 2007).


Phenological changes will alter growing seasons, ecosystem production, population-level interactions and community dynamics (Fitter and Fitter, 2002). Different species show different phenological responses; for example, annuals and insect-pollinated species are more likely to flower early than perennials and wind-pollinated species (Fitter and Fitter, 2002). Ecological research is evaluating these response thresholds to better understand what the wider effects might be. While advancing trends in seasonal events will continue as climate warming increases in the years and decades to come, it is uncertain how different species will respond when temperature thresholds are reached and whether linear relationships between temperature and growing season will be realised in the future.

Data sources

More information about this indicator

See this indicator specification for more details.

Contacts and ownership

EEA Contact Info

Hans-Martin Füssel


EEA Management Plan

2008 2.3.1 (note: EEA internal system)


European Environment Agency (EEA)
Kongens Nytorv 6
1050 Copenhagen K
Phone: +45 3336 7100