Extreme weather link ‘can no longer be ignored’
weather events
weather – the heavy storms, floods and droughts which often fill news bulletins
– as part of a radical departure from a previous equivocal position that many
now see as increasingly untenable.
have formed a new international alliance that aims to investigate exceptional
weather events to see whether they can be attributable to global warming caused
by greenhouse gas emissions.
is “consistent” with climate change. Instead, they intend to assess each unusual
event in terms of the probability that it has been exacerbated or even caused
by the global temperature increase seen over the past century.
attribution” is still in the early stages of development and so is likely to be
pounced on by climate “sceptics” who question any link between industrial emissions
of carbon dioxide and rises in global average temperatures.
weather event with climate change, arguing that the natural variability of the
weather makes it virtually impossible to establish any definitive association
other than a possible general consistency with what is expected from studies based
on computer models.
more aggressive posture, arguing that the climate has already changed enough for
it to be affecting the probability of an extreme weather event, whether it is
an intense hurricane, a major flood or a devasating drought.
about attributing extreme weather events to climate change,” said Peter Stott,
a leading climate scientist at the Met Office Hadley Centre in Exeter.
in the atmosphere and the potential for stronger storms and heavier rainfall is
clearly there.”
between extreme weather and the global climate in which it develops.
in particular it is warmer and more moist than it was 30 or 40 years ago,” Dr
Trenberth said.
and then there is more moisture as well as heat that is available for these storms
[to form]. The models suggest it is going to get drier in the subtropics, wetter
in the monsoon trough and wetter at higher latitudes. This is the pattern we’re
already seeing.”
US National Oceanic and Atmospheric Organisation (NOAA), to carry out detailed investigations of extreme weather events, such as the
vast flooding in Pakistan last year, to see whether they can detect a climate
change “signal” as a likely cause.
a meeting of the World Climate Research Programme in Denver. They hope in future
to assess each extreme weather phenomenon in terms of its probability of being
linked with global warming and then to post the result on the internet.
increase in heatwaves and floods and droughts and extreme rainfall and extreme
temperatures,” Dr Stott said.
extreme temperatures and extreme rainfall are changing. But you can’t jump from
that and say that a specific event is straightforwardly attributable because we
know that natural variability could have played a part.
the links and make more definitive statements about how the risk has changed.
You look sensibly about these things by talking about changing risk, or changing
probability of these events.”
in Europe, in which up to 35,000 people died of heat-related illnesses, as well
as the devastating UK floods in 2000 which cost £1.3bn in insurance claims and
destroyed 10,000 homes following the wettest autumn in England and Wales since
records began in 1766.
gases to global warming substantially increased the risk of such extreme events
occurring. The group is also investigating the exceptional warm April in Britain
this year, which was the warmest since central England records were kept in 1659
and 0.5C warmer on average than the previous warmest April.
US and the flooding of major rivers such as the Mississippi and Missouri led many
people to question whether they were exacerbated by global warming. In the past
scientists would have been reluctant to link single weather events such as these
with climate change, but Dr Trenberth believes this is wrong.
that the environment in which all of these storms are developing has changed,”
Dr Trenberth told The Independent.
memory of the system and the main memory is in the oceans and the oceans have
warmed up substantially, at depth, and we can measure that. I will assert that
every event has been changed by climate change and the main time we perceive it
is when we find ourselves outside the realms of the previous natural variability,
and because natural variability is so large this is why we don’t notice it most
of the time.
10 per cent of the time, that’s when we begin to notice. The main way we perceive
climate change is in changes in the extremes? this is when we break records.”
years on record for natural disasters, nine-tenths of which were related to extreme
weather, such as the floods in Pakistan and eastern Australia and heatwave in
Russia, which is estimated to have killed at least 56,000 people, making it the
most deadly natural disaster in the country’s history.
alone. No, the probability is that climate change is contributing to some of the
warming of the world’s oceans,” said Peter Höppe, author of the Munich Re report.
through south-eastern United States in April; 131 were killed in Alabama alone.
Fifteen people died in Tuscaloosa and sections of the city were destroyed.
to St Ives, but fears of drought were raised. Rainfall in the UK that month was
only 52 per cent of the long-term average.
dried up and people were walking or using bicycles on areas where canoes and river
boats had been the only means of transport.
it caused the destruction of New Orleans when levees were overwhelmed. Some 90
per cent of residents of south-east Louisiana were evacuated.