[A-List] Scorched Earth: climate change

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

In India, the monsoon fails. In Europe, it rains without mercy. Is this
more than a coincidence?
By Steve Connor Science Editor
The Independent, 13 September 2002

It was coursing down in Corsica, pouring in Prague and soaking in
Salzburg. The umbrella-weather of Umbria was matched by rain in Spain
and torrents in Turin. There was almost nowhere in central and southern
Europe that escaped this summer's record downpour.

Majorca suffered its wettest August for more than a quarter of a
century. In just one day violent storms dumped three times the average
monthly rainfall for August on Palma and on neighbouring Ibiza five
times the month's average fell over 24 hours.

Massive flooding in central Europe claimed more than 100 lives and
caused billions of pounds of damage to some of the continent's most
historic sites. Earlier this week, flooding killed at least 20 people in
the south of France, which was hit by some of the most violent weather
in living memory.

As the heavens opened this summer and thousands of Britons sat shivering
in their holiday villas, another devastating phenomenon was taking place
on the other side of the world with even greater consequences - only a
third of the expected rainfall fell during this year's Indian monsoon.

Scientists now believe that these two events are related. The failure of
the monsoon in India, which is so vital for crops, may have led directly
to a breakdown in the normally settled summer weather of southern and
central Europe.

Professor Brian Hoskins, a meteorologist from Reading University, said
yesterday that there was now convincing evidence that the poor summer in
Europe resulted from changes in atmospheric pressure caused by the
failure of the Indian monsoon.

"We've looked back over the last 40 years and certainly the extreme
events of the two seem to hang together," Professor Hoskins told the
annual meeting of the British Association for the Advancement of Science
at Leicester University.

"Don't go to the Mediterranean for your summer holiday before the Indian
monsoon has started because that's when both kick in. It happens every
year. The Indian monsoon starts and then the Mediterranean becomes
settled," Professor Hoskins said.

Normally, as the monsoon season arrives, huge volumes of air begin to
rise over the Indian subcontinent. These push north and west, allowing
other columns of air to descend over the Mediterranean region, causing
stable, high-pressure systems to develop, which repel unstable,
rain-bearing weather. "The rising of air over India actually causes
descent over the southern Mediterranean. That rising over India is much
weaker this year so the descent over the southern Mediterranean is much
weaker. So normally that descent gives high pressure and settled weather
and this year that's not there, which has allowed low pressure systems
to develop," Professor Hoskins said.

But that is just part of a bigger, global story with its beginnings over
the southern Pacific Ocean where an El Niño - an unusual ocean current
- is beginning to grow in strength. Meteorologists now believe El Niño
is behind the failure of the Indian monsoon.

"There's been some very interesting events this summer. One is a
developing El Niño in the Pacific, the second is almost a complete
failure of the Indian monsoon, which is really going to be disastrous
for India and its crops and the other is the flooding in Europe,"
Professor Hoskins told the Science Festival.

"I can relate those three events. Work we've done over the years has
suggested that the settled summer weather over southern Europe is
actually part of the Indian summer monsoon.

"What's happened this year is that the Indian summer monsoon is very
weak and that has released this control over southern Europe and allowed
these low-pressure systems to come in. This is a bit of a hypothesis at
the moment but there is a lot in the data to suggest this," he said.

As much as it matters to European holidaymakers whether their summer is
going to be wet or sunny, it matters far more for Indian farmers whose
crops rely so heavily on a regular monsoon soaking.

Professor Hoskins said that scientists might soon be able to predict
whether a monsoon failure is likely.

"Our ability to predict the Indian monsoon is crucial for those who live
in India, and that's clearly the number one thing. The amazing thing
about the Indian monsoon is not how much it varies but how little it
varies," Professor Hoskins said.

"The typical variation of the rainfall in India is within 10 per cent.
If it's plus 10 per cent then you get people drowning and if it's minus
10 per cent you get people dying from starvation. So what we are looking
at in climate change is whether we are going to perturb that very
subtle, seemingly stable system - although it is probably quite fragile
as well.

"I think with the Indian monsoon we should be able to give some idea of
its probability, although we can't do it with confidence now. I would
think within the next five years or so we would get a more confident
prediction of the probability distribution of the Indian monsoon and
then we'd get an idea of the European situation beyond that," he said.

Freak weather has also been seen in China, where torrential rain has
caused a risk of flooding on an unimaginably large scale, according to
Professor Ian Cluckie, a flood engineer at the University of Bristol who
has just returned from a trip to the regions worst affected. "If you
were a Chinese meteorologist you wouldn't be talking about the failure
of the monsoon, you'd be talking about one that has developed to a much
greater extent. The Chinese flooding which is still going on is due to
an extremely wet monsoon."

Although the link with the Chinese monsoon was not proved, it was part
of a pattern. Flooding was rapidly becoming one of the most prevalent
natural disasters everywhere in the world, he said. "Until the early
1980s, more people died in drought than flood. From the early 1980s,
floods overtook droughts. About 140 million people around the world are
affected by floods and 40 million people are affected directly by
drought," Professor Cluckie said.

"You could interpret this as closely associated with climate change
because it's exactly the period of increasing temperatures caused
essentially by greenhouse gases," he added.

The climate scientists, however, are still unsure about the role played
by increasing temperatures. "There is always the question, 'Is this
global warming?' and we turn around and say, 'Well, we can't say this is
global warming'," Professor Hoskins said.

But the signs are ominous. Computer models of a warmer world predict
greater weather instability, with more extremes in temperatures and
rainfall - which is just what happened this year in Europe and in India.

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The real reason for Manchester's weather - pollution
By Steve Connor
The Independent, 13 September 2002

Manchester's reputation as the wettest city in Britain could have
something to do with its industrial heritage, says an environmental
scientist who believes urban regeneration and pollution can lead to
local increases in rainfall.

Professor Christopher Collier of the University of Salford said that
Manchester's linger-ing drizzle was probably the result of air
pollutants affecting the size of raindrops and that regeneration of the
city's Victorian landscape was also influencing local climate.

"The regeneration projects, in Salford particularly, have led to
increases in rainfall downwind of the urban regeneration area. But in
other directions the rainfall has actually been suppressed by the air
quality," Professor Collier told the Science Festival.

"The explanation we are offering [for Manchester's wet weather] is that
the air quality is poor in the north of the city. The change in
particulates in the air has the effect of reducing the size of raindrops
to drizzle drops and of course Manchester has a reputation for cloudy
drizzle," he said.

Urban regeneration, with the demolition of Victorian buildings and their
replacement by tower blocks and open spaces - which increases the
"roughness" of the landscape - had also played a role in redistributing
local rainfall, Professor Collier said.

"If we change the fabric of city areas in some ways we will change the
distribution of temperature and rainfall. In some areas it might not
increase temperatures or rainfall, it might have the opposite effect.

"But there is definitely going to be changes and in Manchester we found
that 7 to 8 per cent of the increase in rainfall we think is due to the
regeneration of the Salford area and the changing roughness there."

The "heat island" effect of cities was well known, he said. "Cities
expend much more energy than surrounding rural areas, which actually
lose heat, particularly in winter, at a much quicker rate. The buildings
essentially hold the heat and these two work together to produce this
temperature difference."

Plans to increase housing density in the South-east from about 24
dwellings per hectare to 30 or 50 might affect local weather. "These
changes may have a magnitude comparable, or certainly approaching the
changes due to climate changeand we need to understand the complexities
of how these changes interact."