[A-List] Climate change update

["Michael Keaney" <michael.keaney@xxxxxx>]

Climate change doubles Britain's stormy weather

Paul Brown in Milan
Wednesday December 10, 2003
The Guardian

Britain has become twice as stormy in the past 50 years as climate change
has forced the deep depressions that used to hit Iceland further south, it
was revealed yesterday. In a second disturbing discovery, the Hadley Centre
for climate prediction and research in Exeter added that pressure changes in
the atmosphere had caused storms to become more intense.

While low pressure areas which bring high wind and rain are getting deeper,
the high pressure areas which bring calm, settled periods are getting
stronger. The increased gradients between the two make for more dramatic
weather - and for insurance companies, expensive claims for damaged
buildings and fences.
Geoff Jenkins, head of the Hadley Centre, released the figures at the
climate change convention meeting in Milan, where politicians are still
trying to reach agreement on the Kyoto protocol to start legally binding
reductions in greenhouse gas releases to the atmosphere.

The report says whatever politicians decide, some climate change and sea
level rise is already built into the system and current trends will
accelerate.

"The contrast between the slight decrease in the number of storms in Iceland
and the increase over the UK is pretty conclusive evidence that the storm
track, or North Atlantic oscillation as we call it, has moved south," Dr
Jenkins said.

"As far as the pressure anomaly is concerned, this is much higher than we
predicted in our models, and it basically means that the westerly winds
across the British Isles have increased in strength. This is significantly
larger than explicable by natural variation, and must be man-made climate
change."

According to the classic weather model, there was high pressure over the
Azores and low pressure over Iceland, with British weather in between the
two. Peter Stott, the Hadley scientist who carried out the study, said the
high pressure over this country was around 1,030 millibars, and the low
pressure 970.

But over the past 50 years, the high pressures have increased on average by
three millibars and the lows have deepened by the same amount. This has led
to an increase in the winds and in wind damage.

A collaboration between Britain, Canada and Australia established anomalies
across the globe but nowhere were they greater than over northern Europe and
particularly the UK. A telling graphic produced by the researchers of the
observed storm track - the line between high and low pressure belts - shows
England just to the south of the main track and northern Scotland right in
its path.

Because the instruments used to measure wind speeds were unreliable and
liable to be moved from time to time, Dr Stott said, scientists had used an
alternative method to measure storms. "Out at sea what fishermen and all
sailors have learned to dread is a sudden drop in pressure. If the barometer
drops 10 millibars in three hours... it means there will be a gale or worse.
Examples of that happening in the UK weather record have doubled over 50
years. That is very significant statistically."

Although Dr Jenkins is confident the increased intensity of high and low
pressures can be attributable to climate change and is a significant
development in understanding the science, the long-term storminess trends
are more uncertain.

While researchers have been able to use the data for the past 50 years to
establish that storms have increased, they do not have any reliable data for
the 50 years before that to establish whether it was as stormy in 1900s as
it is now.

The Hadley report also records a continued steep rise in global temperatures
during 2003, and it shows average land temperatures across the world were 1C
higher than a century ago for the first eight months of this year. In
England, the warmest January-to-September period was recorded in central
England since records began in 1659, including the hottest day ever
recorded, at 38.5C (101.3F)

Dr Stott said warmer weather had continued since September and 2003 was
heading towards being the warmest year recorded in Britain.


Drier summers, wetter winters - and little snow


· Average annual temperatures may rise by between 2 and 3.5 C by the 2080s,
with greater warming in the south and east than in the north and west of the
UK. Hot, humid summers will become more frequent and very cold winters will
become increasingly rare

· The 1990s was the warmest decade in central England since records began in
the 1660s and this warming of climate over land has been accompanied by
warming of UK coastal waters. 2003 is on track to be the warmest year on
record

· Winters will become wetter and summers may become drier across all of the
UK. The largest changes will be in the south and east, where summer rainfall
may decline by up to 50% by the 2080s. The amount of snow could decline by
60%-90% by the 2080s

· Snowfall will decrease throughout the UK. The reductions in average
snowfall over Scotland might be between 60% and 90% (depending on the
region)

· Average sea level around the UK is now about 10cm (4ins) higher than in
1900 and levels could be between 26 and 86cm above the current level in
south-east England by the 2080s. Extreme high water levels, which currently
have a 2% annual probability, could become 10 to 20 times more frequent at
some east coast locations

· The thermal growing season for plants in central England has lengthened by
about one month since 1900

· Source: Climate Change Scenarios for the United Kingdom: The UKCIP02
Briefing Report