Speckled wood butterfly | Jim Asher
Frequent droughts and habitat loss could push
drought-sensitive butterflies in the UK to local extinction by the
middle of the century, new research suggests.
Even in a very optimistic scenario, where habitat is
improved, the likelihood of these butterflies surviving climate
change drops to zero by 2100, if emissions stay very high.
The "alarming" results highlight the need to limit
climate change by capping emissions, the lead author tells Carbon
Very hungry caterpillars
In the summer of 1995, the UK experienced an
exceptionally dry summer, the most
arid since records began in 1776. Among the impacts of the
hot, dry season, the population of several species of butterfly
collapsed, says Dr Tom Oliver, a
researcher at the UK's Centre
for Ecology and Hydrology.
Heatwaves and droughts affect adult butterflies, says
Oliver, but caterpillars are even more sensitive to extreme
weather, he explains to Carbon Brief:
"If their host plants dry out
under prolonged severe drought then this can cause death or, at the
very least, reduce the quality of their food so that they grow very
Populations of some species of butterfly took several
years to recover to normal levels, says Oliver.
likely to become more frequent as the climate warms,
Oliver set about testing what effect this could have on butterfly
numbers. Looking at data from the UK Butterfly Monitoring Service
(UKBMS), they identified six
species that tend to suffer a fall in number after dry years and
suffered a major drop after the 1995 drought.
The six species of butterfly considered in the study: a)
Cabbage white, b) Small cabbage white, c) Ringlet, d) Green veined
white, e) Speckled wood, and f) Large skipper. Source: Oliver et
The results of the study, published in Nature
Climate Change, suggest that rising temperatures and fragmented
habitats could mean we lose entire species of butterfly by the
middle of the century.
With global temperature as it is today, we wouldn't
expect another drought as severe as 1995 for more than 200 years.
But climate change will drastically cut this return time in the
future, the researchers say.
Even if global temperature rise is held at 2C above
pre-industrial levels - that's
1.15C above the warming we've already seen to date - we
could still expect to see a drought as serious as 1995 every six
years. On the other hand, if emissions stay very high, a severe
drought could be expected almost every year.