http://www.guardian.co.uk/climatechange/story/0,12374,997248,00.html
The
heat is on... and it's getting hotter still
Temperatures over the past decade are the highest
for 2,000 years, scientists say
Robin McKie, science
editor
Sunday July 13, 2003
The Observer
Britain will swelter
in the year's hottest weather this week
as temperatures soar to record levels over the next couple of
days. And there is more to come, say the forecasters - a lot more.
After one of the warmest
Junes on record, July is shaping up
to be another blistering month, they say. And in future things
are only going to get hotter.
The world has already
experienced spiralling temperature rises
that made the last few years the hottest on Earth for more than
2,000 years. All the signs indicate that this increase will
continue indefinitely, scientists add.
As warm air continues
to pour into Britain from the continent
and the tropics, temperatures in southern England should reach
31C tomorrow - the highest of the year - while in central and
northern England they will reach 27C and in Scotland around 24C.
However, the sticky heat is also likely to bring thunderstorms
to central England, Wales and the South by Tuesday.
Britain's mid-July
heatwave is particularly noteworthy because
it arrives at the tail end of several weeks of very hot weather.
There were 214 hours of sunshine last month (compared with 172
last June), an increase of 15 per cent on the average figure for
June between 1961 to 1990. The average temperature for June 2003
was 15.5 degrees compared with 13.9 for June last year - though
this is still a bit short of the 16.2 for 1976, the hottest
June on record.
The prospect of continued
heatwaves was underlined last week
by a scientific report showing that global warming is being
accelerated drastically by human activity, and is not the
result of climatic variation.
The research by Michael
Mann of the University of Virginia
and his team involved analysis of lake sediments, fossil trees
and glacier samples. These show very little variation in
temperatures in either hemisphere for the past 2,000 years
- with one exception: the last 10 years. On both sides of
the equator, and at all latitudes, temperatures have soared.
The study is striking
because it contradicts findings earlier
this month which suggest that our current hot weather is
relatively mild compared with that experienced by Britain
in the Early Middle Ages. The earlier research - by Will Soon
and Sallie Baliunas of the Harvard-Smithsonian Centre for
Astrophysics - focuses on historical records and concludes
that between AD800 and 1100, Britain, and much of Europe,
was actually warmer and happier than today. Vineyards
flourished when the Normans invaded, they point out,
while the Vikings established farms in Greenland.
Agriculture is still impossible there, they add.
We are therefore not
living in a period of unprecedented
warmth, Soon and Baliunas conclude, and are not victims
of industries who pump gases into the atmosphere.
But many leading climatologists
have questioned the study,
pointing out that it only covered a relatively small portion
of the planet's surface and was therefore not representative
of global trends. It is this point that Mann and his group
have tackled.
They looked at fossil
tree rings, from Canada to Mongolia
and from New Zealand to Patagonia and studied ice cores
- which contain air that has been trapped for centuries
- from Tibet, Peru, Greenland and Antarctica to get a
global pattern.
Their conclusion is
simple: the only significant deviation
from average temperatures occurred after 1990 with a rise
of about 0.5 C across the globe. 'It becomes increasingly
less plausible that natural variability can explain late
20th-century warming,' says Mann in Eos, the newspaper of
the American Geophysical Union.
However, global warming
caused by industrial emissions
that will take decades to reverse will not necessarily
bring continued soaring temperatures to our shores.
Melting polar caps could divert the Gulf Stream and
trigger weather patterns more like those of Canada,
meteorologists warn.
Until that happens,
things look balmy, however:
spring is arriving earlier and earlier, and autumn
later and later; while average summer temperatures
inexorably rise - including this year's. 'It's going
to be really, really warm,' said a forecaster.
'It should also be dry in most of the country,
though there may be showers in Scotland.'
The scorching weather
has also revealed evidence
that more and more Britons are adjusting to the
prospect of semi-tropical summers. Last year bottled
water sales rose 11 per cent on the previous year,
and reached a record retail value of £1 billion;
Sainsbury's reported that weekly sales of bottles
of Pimms during Wimbledon reached 200,000, almost
treble the level of 2002; and supermarkets have
reported that sales of barbecue equipment continue
to rise dramatically.
· Additional
research: Tania Valdemoro
