2012 has become infamous as the
wettest year on record in England. Infamous, at least, in England. This has been
followed by a peculiarly long winter, the coldest for fifty years. Britain has
had a run of wet summers. One outcome was a recent meeting by climate
scientists hosted by Exeter University to try and make sense of the signals from
the noise and ,perhaps, the causes. The immediate driver appears to be the jet
stream, which has not been shifting as far north has it once did and, instead,
acts as a conveyor hauling Atlantic depressions across the UK, one after the other.
However what causes the jet stream to linger so far south remains unclear (http://metofficenews.wordpress.com/2013/06/18/meeting-on-uks-run-of-unusual-seasons/)
. Ponds make immediate and powerful indicators of the impacts of these variations
in our climate. The photos above show one of the subsidence ponds at Blakemoor
Farm in the summer of 2012, when it was festooned with deep banks of Celery
Leaved Buttercup, to summer 2013, when it has dried out, leaving a few forlorn
tufts. What is the most worrying; being awash or being dried out? Neither. The
pond comes and goes and with it the vegetation. The animals are less obvious
but they too wax and wane between years. The extreme year of 2012 created an opportunity
for plants and animals that seldom colonised or, even if they did, dominated
the ponds. The ability of a landscape to vary has always struck me as important, although a
tricky thing to measure, given how short term so much of our research is. We find it hard enough to describe what we can capture and count, letalone something as abstract as the potenital to change. The
variation between years has added to the overall biodiversity, allowing wet and
dry year communities to flourish. The risk is that we have not recorded enough
data for sufficient years to spot any major step changes, those thresholds
beyond which the stage is re-set and some of the cast of ecological characters never re-appear.
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