Current warming and likely future impacts - Climate Change: Biological and Human Aspects - page 270

2004 (based on real observations coupled with a computer model dividing these world
regions into smaller - 5 ◦ by 5 ◦ latitude/longitude - cells of different climate change
response, and greatly dominated by warming cells). Meanwhile they searched the
literature for long-term biotic and abiotic studies and selected only those that lasted
more than 20 years. Altogether they compiled around 29 500 time series (28 754 biotic
and 688 abiotic) of response. More than 28 000 were European phenological series
but the remainder were from across the globe: this study was remarkable. (There
will be more on phenology in the next section.) Excluding the European phenology
studies, the majority of the remaining biotic time series related to terrestrial biology
and only around 100 or so to marine and freshwater biology. A handful of agricultural
and forestry time series were also included.
What the Rosenzweig et al. study showed was that in all their global regions abiotic
systems exhibited a response consistent with warming to at least 94% significance (in
other words the response was so great that if analysing the analogous series from 100
parallel Earths only six could be attributable to chance variation and 94 to warming).
With biotic systems this was at least 88% significance (North America and Asia). In
Europe where there had been a large volume of phenological studies, and a total of
28 117 biotic time series examined, the biotic response was consistent with warming
to 90% significance. The global region abiotic response was at least 96% significant.
The conclusion was that anthropogenic climate change is having a significant impact
on physical and biological systems. (A summary overview of this work by Francis
Zwiers and Gabriele Hegerl, 2008, appeared in the same issue of Nature as the study
by Rosenzweig et al.)
6.1.4 Phenology
Aside from changes in species ranges (spatial distributions), phenological data are, as
mentioned in the previous section, the other main indicator of a climatic fingerprint.
Phenology is the study of a plant or animal's progression through its life cycle in
relation to the seasons. Phenological records have been built up over the past few
centuries. In Britain the oldest phenological record known is a diary entry for the first
cuckoo of spring in Worcestershire in 1703. But the association between the arrival
of spring and certain species is much older. For example, the Romans in Britain knew
all about the arrival of spring and the returning of the swallow from its overwintering
in Africa. However, it was many hundreds of years before phenological data began to
be assembled systematically. Arguably the first, which began with observations from
1736, was the English Norfolk country gentleman Robert Marsham's collection of
'27 indications of spring'. Others, such as Thomas Barker of Rutland and Gilbert
White of Selborne, Hampshire, were also keen observers of nature and kept pheno-
logical diaries. Gilbert White even compared his own records with those of a friend
in Sussex. Phenological observation has been a popular activity for professional bio-
logists and amateur natural historians ever since, so much so that between 1875 and
1947 the Royal Meteorological Society managed a voluntary national network of
recorders (Sparks and Collinson, 2003).
As for the changes in phenology that these records reveal in Britain, a very loose
rule of thumb is that it appears that flowering and leafing occur 6-8 days earlier