Year of the big heat

By MICHAEL McCARTHY

It was the summer, scientists now realise, when global warming at last made itself unmistakably felt. People in the Northern Hemisphere knew that summer was remarkable this year.

Britain had record high temperatures; Europe had out-of-control forest fires, great rivers drying to a trickle and thousands of heat-related deaths.

But how remarkable that summer was is only now becoming clear.

June, July and August were the warmest three months recorded in western and central Europe. And they were the warmest by a very long way.

Like Britain, Portugal, Germany and Switzerland had record national highs.

Over a great rectangular block stretching from west of Paris to northern Italy, taking in Switzerland and southern Germany, the average temperature for the summer months was 3.78C higher than the long-term norm, says the Climatic Research Unit of the University of East Anglia in Norwich, one of the world's leading institutions for monitoring and analysis of temperature records.

That might not seem a lot until you are aware of the context. But then you realise it is enormous. There is nothing like this in previous data.

It is considered so exceptional that Professor Phil Jones, the climate unit's director, says openly - in a way that few scientists have done - that this year's extreme may be directly attributed to global warming caused by human actions, rather than natural climate variations.

Meteorologists have hitherto contented themselves with the formula that recent high temperatures are "consistent with predictions" of climate change.

For the great block of the map in question, the unit has reliable temperature records dating back to 1781.

Using as a baseline the average summer temperature between 1961 and 1990, departures from the temperature norm, or "anomalies", can easily be plotted.





Over the past 200 years, there have been at least half a dozen excess temperature anomalies approaching, or even exceeding 2C.

But there has been nothing remotely like this year, when the anomaly is nearly 4C.

"This is quite remarkable," Professor Jones said.

"It's very unusual in a statistical sense. If this series had a normal statistical distribution you wouldn't get this number. The return period [how often it could be expected to recur] would be something like one in 1000 years.

"If we look at an excess above the average of nearly 4C, then perhaps nearly 3C of that is natural variability, because we've seen that in past summers.

"But the final degree of it is likely to be due to global warming, caused by human action."

This year's summer has in a sense been one that climate scientists have long been expecting.

Until now, the warming has been manifesting itself mainly in winters that are less cold rather than in summers that are much hotter.

Last week, the UN predicted that winters were warming so quickly that winter sports would die out in Europe's lower-level ski resorts.

But sooner or later the unprecedented hot summer was bound to come - and this year it did.

Over a large swathe of the western part of the European continent, records were broken in all three months.

It wasn't only monthly averages, but daily extremes and the lengths of spells above thresholds.

National records were set in at least four countries.

Britain experienced its record high on August 10 when the mercury registered 38.5C (101.3F) at Faversham in Kent - the first time the British Isles had recorded a three-figure Fahrenheit temperature.

Germany had a record 40.8C (105.4F), Switzerland one of 41.5C (106.7F) - Swiss data show the summer as the hottest since at least 1500 - and Portugal a quite astonishing 47.3C (117.1F).

Although France's national record still stands at the 44C (111.2F) registered at Toulouse on August 8, 1923, the country suffered severely from "La Canicule", the heatwave, which was headline news for most of the late summer.

In southern and eastern France, says Professor Jones, 29 sites had temperatures of more than 40C (104F) during August. The highest was 42.6C (108.7F) at Orange in the Rhone Valley.

One of the most dramatic features of the summer was the hot nights, especially in the first half of August.

In Paris, the temperature did not drop below 23C at all between August 7 and 14, and the city had its hottest night on August 11-12, when the mercury did not drop below 25.5C.

Germany had its warmest night at Weinbiet in the Rhine Valley with a lowest figure of 27.6C (80.6F) on August 13, and similar night-time temperatures were recorded in Switzerland and Italy.

The high night-time temperatures have been related to the 15,000 extra deaths in France during August, compared with previous years.

They gradually increased during the first 12 days of the month, peaking at about 2000 a day on August 12 and 13, then dropped dramatically after August 14 when minimum temperatures fell by about 5C.

The elderly were most affected - the death rate in those aged more than 75 rose 70 per cent.

For Britain, the full year as a whole is likely to be the warmest recorded.

But despite the temperature record on August 10, the summer itself - defined as the June, July and August period - comes behind 1976 and 1995, when there were longer periods of intense heat.

At the moment, the year is likely to be the third-hottest in the global temperature record (which goes back to 1856), behind 1998 and last year.

But when the records for October, November and December are collated, it might move into second place.

The 10 hottest years in the record have occurred since 1990.

Professor Jones is in no doubt about the astonishing nature of this year's European summer.

"The temperatures recorded this year were out of all proportion to the previous record," he said.

"It was the warmest summer in the last 500 years and probably away beyond that. It was enormously exceptional."

His colleagues at the University of East Anglia's Tyndall Centre for Climate Change Research are planning a study of it.

"It was a summer that has not been experienced before, either in terms of the temperature extremes that were reached, or the range and diversity of the effects of the extreme heat," said the centre's executive director, Professor Mike Hulme.



"It will certainly have left its mark on a number of countries as to how they think and plan for climate change, much as the 2000 floods revolutionised the way the Government is thinking about flooding in the UK.

"The 2003 heatwave will have similar repercussions across Europe."

- INDEPENDENT


Climate change