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Responses to a Warming World

Authors:
Josep Penuelas at Spanish National Research Council (CSIC)-Centre for Ecological Research and Forestry Applications (CREAF)
Josep Penuelas
  • Spanish National Research Council (CSIC)-Centre for Ecological Research and Forestry Applications (CREAF)
Iolanda Filella at Centre for Research on Ecology and Forestry Applications
Iolanda Filella
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Abstract

Animal and plant life cycles are increasingly shown to depend on temperature trends and patterns. In their Perspective, Peñuelas and Filella review the evidence that global warming during the 20th century has affected the growth period of plants and the development and behavior of animals from insects to birds. The authors warn that changes in the interdependence between species could have unpredictable consequences for ecosystems, that the lengthening of the plant growing season contributes to the global increased carbon fixation, and that changes in phenology may affect not only ecosystems but also agriculture and sanitation.
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www.sciencemag.org SCIENCE VOL 294 26 OCTOBER 2001 793
CREDITS: (TREE) RICHARD KETTLEWELL/ANIMALS ANIMALS EARTH SCENCE;(BUTTERFLY) LAURA SIVELL; PAPILIO/CORBIS
Climate warming (1) is expected to
alter seasonal biological phenomena
such as plant growth and flowering
or animal migration, which depend on ac-
cumulated temperature, that is, the total
heat required for an organism to develop
from one point to another in its life cycle.
These so-called phenological changes are
likely to have a wide range of conse-
quences for ecological processes, agricul-
ture, forestry, human health, and the glob-
al economy. An increasing number of
studies now report changes in plant and
animal cycles from a wide range of re-
gions, from cold and wet to warm and dry
ecosystems. These phenological changes
are sensitive and easily observable indica-
tors of biospheric changes in response to
climate warming.
Phenological changes differ from
species to species (2–12), but some are
substantial (see the figure). In Mediter-
ranean ecosystems, the leaves of most de-
ciduous plant species now unfold on aver-
age 16 days earlier and fall on average 13
days later than they did 50 years ago (7).
In Western Canada, Populus tremuloides
shows a 26-day shift to earlier blooming
over the past century (9). Other shifts are
smaller but go in the same direction. A 6-
day shift to earlier leaf unfolding and a 5-
day delay in autumn leaf coloring over 30
years have been described from Scandi-
navia to Macedonia (4). An earlier onset
of biological spring by about 8 days has
also been reported across Europe for
1969–98 (10, 11) and by about 6 days in
North America for 1959–93 (12). In ma-
rine ecosystems, substantial positive linear
trends in phytoplankton season length and
abundance have been described in areas of
the North Atlantic with warming waters
for 1948–95 (13).
Remote sensing data validate these
ground observations on larger scales. The
Normalized Difference Vegetation Index
(NDVI), which is derived from infrared and
red Earth surface reflectance, scales with
green biomass. NDVI satellite data between
45°N and 70°N for 1982–90 showed an 8-
day shift to an earlier start of the growing
season and a delay of 4 days for the declin-
ing phase (14). New NDVI data suggest
that the growing season has become nearly
18 days longer during the past two decades
in Eurasia and 12 days longer in North
America (15). The data also show a gradual
greening of the northern latitudes above
40°N: Plants have been growing more vig-
orously since 1981, especially in Eurasia.
This lengthening of the plant growing
season is likely to contribute to the global
increase in biospheric activity, which has
been inferred from the
increasing amplitude
of annual oscillations
in the atmospheric CO2between 1960 and
1994 (16). The atmospheric data also sug-
gest an extension of the growing season by
about 7 days in the Northern Hemisphere
between the 1960s and the early 1990s,
mostly after 1980. Accelerated tree growth
across Europe, previously attributed to fer-
tilization by nitrogen compounds and in-
creased CO2(17), may be driven at least
partly by this extended growing season. The
lengthening of the growing season thus
plays a key role in global carbon fixation,
the amount of CO2in the atmosphere, and
related global water and nutrient cycles.
Data on shifts in flowering dates are
abundant and show similar trends. Shifts
to earlier flowering by about 1 week have
been reported in Mediterranean species
for 1952 to 2000 (7), in Hungary for 1851
to 1994 (3), in Wisconsin for 1936–98 (5),
and in Washington, DC, for 1970–99 (6).
These observations agree with model re-
sults, which indicate that the time of maxi-
mum olive pollen concentrations advances
by about 6 days per degree Celsius in the
western Mediterranean (18).
All these plant phenological changes are
highly correlated with temperature changes,
especially in the months before seasonal life
cycle events. Temperature (1) as well as
phenology has changed most noticeably af-
ter the mid-1970s. This correlation does not
necessarily imply a causal connection.
However, available data and current knowl-
edge of plant phenology, including numer-
ous experimental studies (4, 19,20), indi-
cate that the observed changes are mostly
due to the increased temperatures. More-
over, at most sites, the number of freezing
days has decreased sub-
stantially in recent years
(1, 7), decreasing the
probability of frost
damage to young leaves
and flowers (21).
Animal life cycles al-
so depend on climate.
For example, insects are
expected to pass through
their larval stages faster
and become adults earli-
er in response to warm-
ing. Aphid species in the
United Kingdom have
shown a 3- to 6-day ad-
vance in the timing of
different phases in their
life cycle over the past
25 years (22). The date
on which the maximum
numbers of individuals
of the most common
Microlepidoptera in the
Netherlands were count-
ed shifted forward by 12
days on average between 1975 and 1994
(23). Butterflies now appear 11 days earlier
than in 1952 in northeast Spain (7). British
butterflies have not only appeared earlier but
have also shown longer flight periods, that is,
enhanced activity, over the past two decades
(24). In other animal groups, frog calling has
been reported to occur about 10 days earlier
between 1990 and 1999 than between 1900
and 1912 in New York state (25), and bird
species surveyed in the United Kingdom
from 1971 to 1995 showed 9-day shifts to-
ward earlier egg laying (2).
The advanced leafing, flowering, fruiting,
and appearance of insects are likely to ad-
vance the availability of food supplies for
SCIENCE’SCOMPASS
PERSPECTIVES
PERSPECTIVES: PHENOLOGY
Responses to a Warming World
Josep Peñuelas and Iolanda Filella
Image not
available for
online use.
Ecological consequences of climate warming on plant and animal
phenology.
The authors are in the Unitat Ecofisiologia CSIC-
CREAF, Center for Ecological Research and Forestry
Applications (CREAF), Edifici C, Universitat Autònoma
de Barcelona, 08193 Bellaterra (Barcelona), Spain. E-
mail: josep.penuelas@uab.es, i.filella@creaf.uab.es
on January 31, 2008 www.sciencemag.orgDownloaded from
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www.sciencemag.org SCIENCE VOL 294 26 OCTOBER 2001 795
birds. However, a later arrival in Europe of
migratory birds wintering south of the Sahel
has been reported (7, 26). For these species,
the decision when to start spring migration
may become maladaptive when the cue for
migration is independent of the environmental
change in the breeding area (7). Climate
change may thus be a serious threat to species
that migrate from tropical wintering grounds
to temperate breeding areas. They may arrive
at an inappropriate time to exploit the habitat
and compete with larger numbers of individu-
als of resident species as more of them sur-
vive the winter. These arguments may partly
explain the decline of these long-distance mi-
gratory species in Western Europe (8), al-
though short-distance migrants may be more
flexible. These findings support previous re-
sults demonstrating that shifts in global cli-
mate patterns can affect migratory birds (27).
These changes in plant phenology and bird
migration show that climate warming may
lead to a decoupling of species interactions,
for example, between plants and their pollina-
tors or between birds and their plant and insect
food supplies (2). Changes not only in mean
temperatures but also in temperature patterns
may affect these interactions even more
strongly because they may alter the synchro-
nization between species (28). An example of
such decoupling was recently reported. The
Great Tit still breeds at the same time, but its
food supply has been advanced because of
earlier plant development in recent years (29).
Different phenological responses (7, 30) may
alter the competitive ability of different species
and thus their ecology and conservation, re-
sulting in unpredictable impacts on communi-
ty structure and ecosystem functioning.
The observed phenological changes
have occurred with a warming only 50% or
less of that expected for the 21st century
(1). Many ecological (carbon sequestration,
nutrient and water cycles, species competi-
tion, pests and diseases, bird migration and
reproduction, and species-species interac-
tions), agricultural (crop suitability, yield
potential, length of growing season, risk of
frost damage, epidemiology of pests and
diseases, timing and amount of pesticide
use, and food quality), and socioeconomic
and sanitary (duration of the pollen season
and distribution and population size of dis-
ease vectors) factors depend strongly on
plant and animal phenology. Phenology is
therefore increasingly relevant in the
framework of global change studies (31).
As in many areas of environmental sci-
ence, the key requirement is long-term data
sets. Today, thousands of people—profes-
sionals and volunteers—record phenologi-
cal changes all over the world, as do inter-
national and national phenological moni-
toring networks such as Global Learning to
Benefit the Environment (GLOBE) or the
European Phenology Network. Together
with remote sensing, atmospheric, and eco-
logical studies, these data will help to answer
the many questions raised by the recently re-
ported climate effects on phenology: What
are the limits of the lengthening of the plant
growth season and the consequent greening
of our planet? Will the (less seasonal) tropical
ecosystems be less affected than boreal, tem-
perate, and Mediterranean ecosystems? How
will different aquatic ecosystems respond?
How will responses to temperature and other
drivers of global change interact to affect
phenology and the distribution of organisms?
How will changes in synchronization be-
tween species affect population dynamics
both in terrestrial and aquatic communities?
Will appropriate phenological cues evolve at
different trophic levels?
References and Notes
1. Intergovernmental Panel on Climate Change,
Climate
Change 2001: The Scientific Basis. Third Assessment
Report of Working Group I,
J. T. Houghton
et al
., Eds.
(Cambridge Univ. Press, Cambridge, 2001).
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ture
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3. A.Walkowszky,
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Proc.
Natl. Acad. Sci. U.S.A.
96,9701 (1999).
6. M. Abu-Asab
et al.
,
Biodivers. Conserv.
10,597 (2001).
7. J. Peñuelas, I. Filella, P. Comas,
Global Change Biol.
,in press.
8. C. Both, M. E. Visser,
Nature
411,296 (2001).
9. E. G. Beaubien, H. J. Freeland,
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53 (2000).
10. F. M. Chmielewsky, T. Roetzer,
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11. R.Ahas,
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12. M. D. Schwartz, B. E. Reiter,
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13. P. C. Reid, M. Edwards, H. G. Hunt, A. J.Warner,
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391,546 (1998).
14. R. B.Myneni
et al
.,
Nature
386,698 (1997).
15. L. Zhou
et al
.,
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106,20069 (2001).
16. C. D. Keeling, J. F. S. Chin,T. P. Whorf,
Nature
382,146
(1996).
17. H. Spiecker
et al
., Eds.,
Growth Trends in European
Forests: Studies from 12 Countries
(Springer, Berlin,
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18. C. P. Osborne
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.,
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23,701
(2000).
19. W. Larch er,
Physiological Plant Ecology
(Springer,
Berlin, 1995).
20. M.V. Price, N. M. Waser,
Ecology
79,1261 (1998).
21. Note, however, that species requiring a certain num-
ber of frost days for budbursting (
19
) may suffer an
impact not linearly correlated with temperature.
22. R. A. Fleming, G. M. Tatchell, in
Insects in a Changing
Environment
,R.Harrington, N. Stork, Eds. (Academic
Press, London, 1995), pp. 505–508.
23. W. N. Ellis, J. H. Donner, J. H. Kuchlein,
Entomol. Ber.
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57,66 (1997).
24. D. B. Roy, T. H. Sparks,
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6,407
(2000).
25. J. P. Gibbs, A. R. Breisch,
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26. C . F. Mason,
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30. A. H. Fitter
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31. A conference, “The times they are a changing. Climate
change, phenological responses and their conse-
quences for biodiversity, agriculture, forestry and hu-
man health,” will be held in Amsterdam in December
2001; see www.dow.wau.nl/msa/epn/conference.
SCIENCE’SCOMPASS
The walls of higher plants contain small
amounts of a mysterious polysaccha-
ride known as rhamnogalacturonan II
(RGII). RGII is thought to be the most com-
plex polysaccharide on Earth, and its pres-
ence and strong conservation in all higher
plants suggest that it is important for the
structure or growth of plant cell walls. The
study by O’Neill et al. (1) on page 846 of
this issue convincingly shows, 23 years after
its discovery (2), that RGII is essential for
plant growth and that minor changes in its
structure cause growth defects.
More than 300 years ago, Robert Hooke
pointed his primitive microscope at a slice
of cork and discovered the cellular basis of
organisms. Sadly, since then, plant cell
walls, which formed the compartments he
actually observed, have never been consid-
ered particularly entertaining structures. In-
deed, the word wall itself evokes something
dull and rigid, built only to enclose, sup-
port, divide, and protect. However, a closer
look reveals just how erroneous this view
is. Walls of growing plant cells are extreme-
ly sophisticated composite materials made
of dynamic networks of polysaccharides,
protein, and phenolic compounds. Cellu-
lose microfibrils with a tensile strength
comparable to that of steel provide the plant
with a load-bearing framework. These mi-
crofibrils are rigid wires made of crys-
talline arrays of β-1,4-linked chains of glu-
cose residues, which are extruded from lit-
tle hexameric spinnerets in the plant cell
plasma membrane and surround the grow-
ing cell like the hoops around a barrel. Be-
cause cellulose microfibrils constrain tur-
gor-driven cell expansion in one preferen-
tial direction, they control the shape of
plant cells and ultimately that of the plants
themselves. Hemicelluloses, such as xy-
loglucans, are tethered by hydrogen bonds
to cellulose and form cross-links that may
control the separation of the cellulose mi-
crofibril hoops. The cellulose-hemicellu-
lose network is embedded in a matrix of
complex galacturonic acid–rich pectic
PERSPECTIVES: PLANT BIOLOGY
A Baroque Residue in Red Wine
Herman Höfte
The author is in the Laboratoire de Biologie Cellu-
laire, INRA, 78210 Versailles Cedex, France. E-mail:
hofte@versailles.inra.fr
on January 31, 2008 www.sciencemag.orgDownloaded from
... It could be assumed that the growing season length of forests in Europe will be longer with global warming, where spring and autumn temperatures are assumed to particularly affect the phenology (Crabbe et al., 2016). Therefore, vegetation phenology is a relevant indicator to understand the effect of global warming on vegetation, while at the same time, phenology has an impact on water, energy and carbon fluxes (Peñuelas and Filella, 2001;Peñuelas et al., 2009;Richardson et al., 2013;Piao et al., 2019). This makes the phenology a relevant property of terrestrial ecosystems (Peñuelas and Filella, 2001). ...
... Therefore, vegetation phenology is a relevant indicator to understand the effect of global warming on vegetation, while at the same time, phenology has an impact on water, energy and carbon fluxes (Peñuelas and Filella, 2001;Peñuelas et al., 2009;Richardson et al., 2013;Piao et al., 2019). This makes the phenology a relevant property of terrestrial ecosystems (Peñuelas and Filella, 2001). ...
... The phenology information retrieved from Sentinel-1 as demonstrated in this study could be used complementary to frequently used optical data in future studies, which supports potentially the understanding and assessment of phenology with remote sensing on large scale (Tian et al., 2021;Dronova and Taddeo, 2022;Yu et al., 2023). The information of large scale phenology information can support to understand the effect of global warming on the phenology, which in turn affects ecosystem services and water, energy and carbon fluxes (Peñuelas and Filella, 2001;Peñuelas et al., 2009;Richardson et al., 2013;Piao et al., 2019). ...
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View
... 1. Trait and property responses: a. Phenology: warming will lead to earlier spring phenophases, later fall phenophases, and longer flower lifespans as warming shifts the timing of cues that trigger these phases (Parmesan and Yohe 2003;Peñuelas and Filella 2001;Zhou et al. 2022). b. ...
... Interestingly, we also see that fall phenophases have a negative effect size when warmed seasonally, but a slightly positive effect size when warmed year-round. Most climate studies find a delay in fall phenology when plants are warmed (Collins et al. 2021;Peñuelas and Filella 2001;Walther et al. 2002), shown by a positive effect size in this study. Climate change projections show that winter warming will be significant (Kreyling et al. 2019); therefore, year-round warming experiments may more accurately reflect the effects of climate warming. ...
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... Advances of biological spring, such as leaf unfolding or green-up, have been globally recorded based on in situ and remotely sensed observations over recent decades [1][2][3][4] . An earlier start of the growing season (SOS) enhances photosynthesis and spring carbon uptake 5-7 , warms the atmosphere 8 and potentially alters plant-animal interactions 9 . ...
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... Our findings also align with studies from other regions, such as semi-arid Australia, where C 3 grasses flower in cooler seasons (winter and spring), and C 4 grasses flower in warmer seasons (summer and autumn) (Williams et al., 2007). This supports the notion that climate change, characterized by rising temperatures and increased drought frequency, may shift plant communities toward C 4 dominance (Peñuelas & Filella, 2001;Williams et al., 2007). Further analyses show that C 4 plants, such as K. prostrata and C. songorica, exhibited significant increases in relative abundance under warming and N addition (Appendix S1: Figure S9). ...
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... This change has led to a notable increase in annual gross primary productivity, with an estimated increase of 5.8 gC m −2 yr −1 for each additional day of the LOS (Piao et al 2007). However, as the LOS extends, soil carbon decomposition also intensifies (Peñuelas and Filella 2001), resulting in a weaker correlation between annual net ecosystem productivity and changes in the growing season (White and Nemani 2003). This indicates that while the extension of the growing season may enhance carbon uptake, the increase in soil carbon decomposition could offset some of the benefits of carbon absorption (Piao et al 2007). ...
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Estuarine coastal wetland are vulnerable zones of the Earth’s ecosphere, and hygrophilous vegetation responds sensitively to climate change. Vegetation phenology is a key component of global climate change research. However, due to the diversity of vegetation types and the influence of sea-land interaction, the characteristics of phenology in coastal wetlands are poorly understood. Therefore, we took the vegetation in the Yellow River Delta (YRD) wetland in China as a research object. The Gap Filling and Savitzky–Golay algorithm was selected to fuse MODIS_NDVI with Landsat for extracting vegetation phenology based on classification. Then we revealed their spatial-temporal variation and influencing mechanisms. Results showed YRD was rich in vegetation species. In addition to agricultural vegetation, the constructive species included Spartina alterniflora, Tamarix chinensis, Phragmites australis and Suaeda glauca. Vegetation phenology parameters, including Start of the growing season (SOS), End of the growing season (EOS) and Length of the growing season (LOS), showed various patterns in different years. The SOS showed a fluctuating advance trend, with the rate of 1.7 day per year (R² = 0.58, p = 0.032). The EOS was relatively stable, the LOS showed a decreasing and then fluctuating upward trend, with the extended rate of 4.4 day per year. Spatially, SOS and EOS showed a trend of advancement from the northeast to the southwest. The changes in phenology were mainly influenced by spring precipitation and last autumn temperature. Meanwhile, there was a significant seaward phenology pattern of vegetation. The Spartina alterniflora, Phragmites australis, and Tamarix chinensis of SOS and EOS showed a trend of advancing the further they were from the sea. The phenology parameters were significantly different among buffer zones. The distance from the ocean will have an impact on the phenological time of vegetation. Differences in temperature and precipitation within each buffer zone had a significant effect on phenology.
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... Based on the word cloud data (Fig. 5) provided for Cluster 4 − Application, we can see that the most frequent keywords include "Climate Change" (1312 times), "LAI" (1232 times), "Land Use/Land Cover (LULC)" (956 times), and "Yield Prediction" (794 times). These keywords reflect the application of VIs in climate change, vegetation parameters retrieval, land use/land cover, classification, and yield prediction. VI can be used as one of the indicators of climate change, and the response and adaptive capacity of vegetation to climate change can be assessed by monitoring the relationship between VIs and climate parameters (Huang et al., 2023;Peñuelas and Filella, 2001;Wohlfahrt et al., 2019;Zhang et al., 2004). Another important application of VIs is to obtain information on the spatial distribution of LULC and to monitor land cover change to support land management and planning (Feng et al., 2023;Lu et al., 2004). ...
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... Vegetation adapts to climate change in two ways: through fast mechanisms such as changes in physiology and phenology 18,26 , and through slow mechanisms such as genetic adaptations and shifts in community composition 18 . Thus, vegetation has sufficient time to adapt when climate change is slow. ...
Vegetation resistance to compound drought and heatwave events buffers the spatial shift velocities of vegetation vulnerability
Article
Full-text available
  • Apr 2025
Global warming is increasing compound drought and heatwave events. This elevates vegetation loss probability. Despite spatial shifts in vegetation loss probability being crucial for predicting spatial redistribution patterns of vegetation vulnerability across terrestrial ecosystems, they remain poorly understood under compound drought and heatwave events. In this study, using a vine copula model, vegetation loss probability was quantified under compound drought and heatwave events. Spatial shift velocities of vegetation loss probability were examined using the concept of velocity change. Spatial shift velocities of vegetation loss probability would undergo substantial increase based on the satellite observations and future simulations. However, vegetation resistance to droughts buffers spatial shift velocities of vegetation loss probability (p < 0.01). These findings provide evidence that vegetation vulnerability patterns will undergo substantial spatial changes under compound drought and heatwave events, leading to a spatial redistribution of vegetation in disturbance-prone areas.
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... in modifying the albedo effect [11][12][13] . Although the magnitude of urban temperature gradients is a key factor driving phenological differences between urban and rural areas, the composition of tree species-each with distinct responses to warming 5,11,14 -likely plays an equally important role. However, the relative influence of species composition and urban climate on phenological responses to urbanization remains poorly understood. ...
Tree species composition governs urban phenological responses to warming
Article
Full-text available
  • Apr 2025
Urban environments are typically warmer than surrounding rural areas, providing a unique setting for studying phenological responses to climate warming. Phenological differences between urban and rural trees are driven by local climate and species composition. Yet, the extent to which species composition influences phenological responses to urbanization remains poorly understood. To address this, we combine manipulative experiments, satellite-derived phenology data, and georeferenced tree occurrence records. Our findings show that, across Northern Hemisphere cities, differences in the temperature sensitivity of spring phenology between urban and rural areas are largely driven by urban-rural variation in species composition, surpassing the effects of preseason temperature. This pattern is particularly pronounced in Asian cities, where urban areas exhibit 0.74 ± 0.24 days/°C higher temperature sensitivity than rural areas. In-depth analyses using experiments and high-resolution satellite imagery from Beijing further demonstrate species-specific phenological responses to urbanization, with urban-dominant species exhibiting higher temperature sensitivity in urban environments compared to rural ones. These findings show that both interspecific variation in temperature sensitivity and species-specific responses to urbanization contribute to the pronounced impact of species composition on urban-rural phenological patterns. Our study underscores the importance of considering species composition when studying phenological responses to climate warming, especially in urban contexts.
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... Higher temperatures lead to an earlier spring green-up (earlier SOS), later senescence (delayed EOS), and thus to longer LOS (Figures 6 and 7 for Fagus sylvatica and Castanea sativa, respectively). The role of temperature as the main driver of plant phenology has been widely recognized [12,69,70], with many studies finding this elongation effect of temperature [7,58]. Moreover, numerous studies have recorded both the advance of SOS and the delay of EOS due to increased temperature [8,37,49,71]. ...
Climate Effects on Phenology of Two Deciduous Forest Species Across Southern Europe
Article
Full-text available
  • Mar 2025
Monitoring vegetation phenology is crucial for understanding how plants respond to climate change and how the latter affects the role of vegetated ecosystems in biosphere cycles. It has been reported that the growing season has been extended, leading to an increase in global terrestrial productivity, but not much attention has been given to how different climatic variables affect specific tree species’ phenology. This study focuses on the main phenological events (SOS, Start Of Season; EOS, End Of Season; and LOS, Length Of Season) of two deciduous species (Fagus sylvatica L. and Castanea sativa Mill.) and the effects of temperature and precipitation on them. The analysis concerns a 23-year period (2000–2022) of various sites across southern Europe. The dates for each phenological event are estimated based on NDVI timeseries from MODIS satellite sensor. Both species show an elongation of their growing season, with SOS occurring 2.09 and 1.63 days/decade earlier and EOS 2.97 and 3.03 days/decade later for Fagus sylvatica and Castanea sativa, respectively, with this trend appearing more intense at lower altitudes. Temperature seems to be the major driver for these changes for both species, with higher temperatures before each phenological event leading to earlier SOS and delayed EOS. The effects of precipitation are less homogenous, showing different trends between sites and species.
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Reverse Correlation Between Allergic Pollens and Fungi Amounts Annually with Allergic Sensitization Rate to Them
Chapter
  • Jun 2025
A growing number of people have recently contracted allergic diseases caused by pollen because of climate change. The seasonal variations in pollens have occurred with the increased sensitization rate to pollens in children as well as in adults. Allergic plants which are rapidly proliferating have emerged as a dangerous element for allergic children. Plants causing allergies are strongly proposed to be due not only to the rapid proliferation of weeds and trees but also to air pollution such as greenhouse gases as well as increased temperatures resulting from climate change. As an altered climate affects the range of allergenic plant species and the length of the pollen season, a number of studies have shown that increased CO2 levels and atmospheric temperature raise pollen concentration as well as increased allergenicity of pollens with duration of the extended pollen season. Weather variables with CO2 levels are among the main factors affecting phenology and pollen production. Weather patterns influence the movement and dispersion of all aeroallergens depending on atmospheric stability. Otherwise, the atmospheric fungal concentrations decreased annually for 25 years. The intensity of precipitation during the summer and autumn increased, but the number of days with precipitation decreased throughout the seasons. Even though there was an increase in precipitation, it was concentrated over a short period of time. These changes may have augmented dry season duration, which reduced the sporulation period for fungi. Allergenic fungal sporulation could decrease with climate changes in future. There is shown reverse phenomenon between increased allergic pollens and decreased fungi amounts annually with allergic sensitization rate to them. It is yet unknown whether complex interactions with pollens, fungi, meteorological variables, and air pollutants in the changing environment. It is crucial to eliminate the associated risk for human health in future and take appropriate measures to reduce it.
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Increased Plant Growth in the Northern High Latitudes from 1981 to 1991
Article
Full-text available
  • Apr 1997
  • NATURE
Variations in the amplitude and timing of the seasonal cycle of atmospheric CO2 have shown an association with surface air temperature consistent with the hypothesis that warmer temperatures have promoted increases in plant growth during summer1 and/or plant respiration during winter2 in the northern high latitudes. Here we present evidence from satellite data that the photosynthetic activity of terrestrial vegetation increased from 1981 to 1991 in a manner that is suggestive of an increase in plant growth associated with a lengthening of the active growing season. The regions exhibiting the greatest increase lie between 45°N and 70°N, where marked warming has occurred in the spring time3 due to an early disappearance of snow4. The satellite data are concordant with an increase in the amplitude of the seasonal cycle of atmospheric carbon dioxide exceeding 20% since the early 1970s, and an advance of up to seven days in the timing of the drawdown of CO2 in spring and early summer1. Thus, both the satellite data and the CO2 record indicate that the global carbon cycle has responded to interannual fluctuations in surface air temperature which, although small at the global scale, are regionally highly significant.
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Variation in northern vegetation activity inferred from satellite data of vegetation index during 1981 to 1999
Article
Full-text available
  • Sep 2001
The northern high latitudes have warmed by about 0.8°C since the early 1970s, but not all areas have warmed uniformly [Hansen et al., 1999]. There is warming in most of Eurasia, but the warming rate in the United States is smaller than in most of the world, and a slight cooling is observed in the eastern United States over the past 50 years. These changes beg the question, can we detect the biotic response to temperature changes? Here we present results from analyses of a recently developed satellite-sensed normalized difference vegetation index (NDVI) data set for the period July 1981 to December 1999: (1) About 61% of the total vegetated area between 40°N and 70°N in Eurasia shows a persistent increase in growing season NDVI over a broad contiguous swath of land from central Europe through Siberia to the Aldan plateau, where almost 58% (7.3×106km2) is forests and woodlands; North America, in comparison, shows a fragmented pattern of change in smaller areas notable only in the forests of the southeast and grasslands of the upper Midwest, (2) A larger increase in growing season NDVI magnitude (12% versus 8%) and a longer active growing season (18 versus 12 days) brought about by an early spring and delayed autumn are observed in Eurasia relative to North America, (3) NDVI decreases are observed in parts of Alaska, boreal Canada, and northeastern Asia, possibly due to temperature-induced drought as these regions experienced pronounced warming without a concurrent increase in rainfall [Barber et al., 2000]. We argue that these changes in NDVI reflect changes in biological activity. Statistical analyses indicate that there is a statistically meaningful relation between changes in NDVI and land surface temperature for vegetated areas between 40°N and 70°N. That is, the temporal changes and continental differences in NDVI are consistent with ground-based measurements of temperature, an important determinant of biological activity. Together, these results suggest a photosynthetically vigorous Eurasia relative to North America during the past 2 decades, possibly driven by temperature and precipitation patterns. Our results are in broad agreement with a recent comparative analysis of 1980s and 1990s boreal and temperate forest inventory data [United Nations, 2000].
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Growth Trends in European Forests Studies from 12 Countries
Book
  • Jan 1996
The European Forest Institute (EFI) has five Research and Development priority ar­ eas: forest sustainability, forestry and possible climate change, structural changes in markets for forest products and services, policy analysis, and forest sector informa­ tion services and research methodology. In the area of forest sustainability our most important activity has been the project "Growth trends of European forests", the re­sults of which are presented in this book. The project was started in August 1993 under the leadership of Prof. Dr. Heinrich Spiecker from the University of Freiburg, Germany, and it is one of the first EFI's research projects after its establishment in 1993. The main purpose of the project was to analyse whether site productivity has changed in European forests during the last decades. While several forest growth studies have been published at local, re­ gional and national levels, this project has aimed at stimulating a joint effort in iden­ tifying and quantifying possible growth trends and their spatial and temporal extent at the European level. Debate on forest decline and possible climate change, as well as considerations re­ lated to the long term supply of wood underline the importance of this project, both from environmental and industrial points of view. Knowledge on possible changes in growth trends is vital for the sustainable management of forest ecosystems.
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Fitter AH, Fitter RSR, Harris ITB, Williamson MH.. Relationships between first flowering date and temperature in the flora of a locality in central England. Funct Ecol 9: 55-60
Article
  • Feb 1995
1. A data set of 36 years (1954-1989) of observations on first flowering dates (FFD) of 243 species of angiosperms and gymnosperms in one locality in southern central England is presented and analysed. 2. Individual FFDs ranged from 1 January to 17 August, and species varied considerably in the standard deviation of their FFD. The most variable species were mainly annuals and there was a negative relationship between mean FFD and variability, early-flowering species being the most variable. 3. For 219 of the 243 species, it was possible to fit regression equations for FFD to some set of monthly mean temperatures of the preceding months. These fits were generally best for woody plants and geophytes. February temperature was overall the most important determinant of flowering time. Sixty per cent of species flowering between January and April were affected by temperature 1-2 months before flowering; for summer (May onwards) flowering species, temperatures up to 4 months previously were important. 4. High spring temperatures advanced flowering by a mean of 4 days per degree. In contrast, both spring- and summer-flowering species were retarded in flowering by high temperatures in the previous autumn. 5. These relationships were used to simulate the effects of climatic warming: an overall increase of 1-degree-C in each month would advance flowering in some species and retard others, by as much as 6 weeks. Retarded species were early-flowering, advanced species late-flowering. These results suggest a high degree of dependence of flowering time on temperature, and the variation between species implies that responses to climatic warming may be difficult to predict.
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Recent shifts in phenology of Microlepidoptera, related to climatic change (Lepidoptera)
Article
  • Jan 1997
One of the many effects of the warming of the global climate that have been predicted is an acceleration of the larval development of insects. Insect populations living in temperate climates generally have one or more generations per year, punctuated by the winter resting period. We hypothesised that a gradual shift in the timing of these generations towards an earlier date will take place. For this purpose we analysed the phenology of a large sample of the most common Microlepidoptera in The Netherlands. Our results show that during the period 1975-1994 the flight peak has shifted to a date 11.6 days on average earlier. This shift is primarily associated with a rise in spring temperatures. The phenological data are based on a large body of observations brought together at little cost by amateur recorders, and the results suggest a relatively inexpensive method of monitoring future climatic change.
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Effects of Experimental Warming on Plant Reproductive Phenology in a Subalpine Meadow
Article
  • Jun 1998
Increasing 'greenhouse' gases are predicted to warm the earth by several degrees Celsius during the coming century. At high elevations one likely result is a longer snow-free season, which will affect plant growth and reproduction. We studied flowering and fruiting of 10 angiosperm species in a subalpine meadow over 4 yr, focusing on plant responses to warming by overhead heaters. The 10 species reproduced in a predictable sequence during 3-4 mo between spring snowmelt and fall frosts. Experimental warming advanced the date of snowmelt by almost 1 wk on average, relative to controls, and similarly advanced the mean timing of plant reproduction. This phenological shift was entirely explained by earlier snowmelt in the case of six plant species that flowered early in the season, whereas four later-flowering species apparently responded to other cues. Experimental warming had no detectable effect on the duration of flowering and fruiting, even though natural conditions of early snowmelt were associated with longer duration and greater overlap of reproduction of sequentially flowering species. Fruit set was greater in warmed plots for most species, but this effect was not significant for any species individually. We conclude that global warming will cause immediate phenological shifts in plant communities at high elevations, mediated largely through changes in timing of snowmelt. Shifts on longer time scales are also likely as plant fitnesses, population dynamics, and community structure respond to altered phenology of species relative to one another and to animal mutualists and enemies. However, the small spatial scale of experiments such as ours and the inability to perfectly mimic all elements of climate change limit our ability to predict these longer term changes. A promising future direction is to combine experiments with study of natural phenological variation on landscape and larger scales.
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Long-term changes in arrival dates of spring migrants
Article
  • Nov 1995
Data on the spring arrival dates of 23 species of migrants in Leicestershire over a 50-year period are presented. Chiffchaff, Sand Martin, Blackcap and Sedge Warbler showed a significant trend towards earlier arrival over the period, while Tree Pipit, Cuckoo, Whinchat, Whitethroat and Garden Warbler showed a significant trend towards later arrival. Fifteen species arrived noticeably earlier in the 1940s, a period of warm springs, while several species showed earlier arrivals in the 1980s. A number of species showed later arrival dates in the 1960s and 1970s, when April temperatures were colder than average. Several species showed significant correlations between arrival date and temperature. Arrival dates of the earliest species were much more variable than those arriving later, while species arriving in the second half of April showed a generally synchronous arrival. The results are discussed in the context of global warming.
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Insects in Changing Environment
Book
  • Dec 1995
This book, from a 1993 symposium, focuses on current, anthropogenic changes in insect populations using five major sections: introduction; changes in climate; changes in gas/pollutant levels; changes in land use; and a section of shorter papers. The effects of climate change on insects are assessed using techniques ranging from fossil evidence to simulation models to remote sensing. The section on changes in gas levels addresses a series of individually studies of insect responses to atmospheric gases and other pollutants. The section focusing on the effects of environmental change on insects is well documented.
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Increased activity of northern vegetation inferred from atmospheric CO2 measurements
Article
  • Jul 1996
THROUGHOUT the Northern Hemisphere the concentration of atmospheric carbon dioxide rises in winter and declines in summer, mainly in response to the seasonal growth in land vegetation1–4. In the far north the amplitude of the seasonal cycle, peak to trough, is between 15 and 20 parts per million by volume5. The annual amplitude diminishes southwards to about 3 p.p.m. near the Equator, owing to the diminishing seasonally of plant activity towards the tropics. In spite of atmospheric mixing processes, enough spatial variability is retained in the seasonal cycle of CO2 to reveal considerable regional detail in seasonal plant activity6. Here we report that the annual amplitude of the seasonal CO2 cycle has increased by 20%, as measured in Hawaii, and by 40% in the Arctic, since the early 1960s. These increases are accompanied by phase advances of about 7 days during the declining phase of the cycle, suggesting a lengthening of the growing season. In addition, the annual amplitudes show maxima which appear to reflect a sensitivity to global warming episodes that peaked in 1981 and 1990. We propose that the amplitude increases reflect increasing assimilation of CO2 by land plants in response to climate changes accompanying recent rapid increases in temperature.
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