By Renee Maltezou and Kate Holton
ATHENS/LONDON (Reuters) - Emergency services battled wildfires across swathes of southern Europe amid mass evacuations on Wednesday, as warnings sounded in London after Britain's hottest day that the fight against climate change needed to be stepped up.
Hundreds fled in central Italy as gas tanks exploded in a forest fire near the Tuscan town of Lucca. Similar numbers fled in Greece as a blaze fuelled by gale-force winds raged in mountains north of Athens. Greek authorities said later in the day that the blaze had been tamed.
A brutal heatwave with spikes well above 40 Celsius (104F) settled over southern Europe last week, part of a global pattern of rising temperatures, widely attributed by scientists and climatologists to human activity. It is forecast to dump searing heat on much of China into late August.
It is also expected to expose around 100 million Americans to temperatures above 38C on Wednesday and set records in Texas, Louisiana and Arkansas.
Power consumption is predicted to hit new peaks in Central U.S. states - adding to greenhouse gas emissions - as homes and businesses crank up air conditioners to combat a heatwave forecast to last into next week.
While the record heat last week around parts of the Mediterranean has eased, mercury readings have begun heading up again in Portugal, Spain and Italy.
Armando Silva, Civil Protection commander in Portugal's northern region, said rising temperatures and strong winds would make it harder to fight the country's largest wildfire centred on the municipality of Murça.
It has burned 10,000-12,000 hectares (38-46 square miles) since Sunday and around 800 firefighters and six water planes have been deployed to tackle it.
In Spain, where emergency crews were fighting fires in five regions, national weather service AEMET also forecast higher temperatures.
Wildfires burned in several areas of Italy, including one that threatened to leave part of the northeastern city of Trieste without power and water, and 14 metropolitan areas including Rome, Milan and Florence were due to be put on the country's highest heatwave alert on Thursday.
Forecasters there said that temperatures were expected to hit 40C across a swathe of the north and centre this week.
That mark was topped in Britain for the first time on Tuesday, shattering the country's previous temperature record by 1.6 degrees Celsius. At least 13 people have died while swimming to cool off.
The Chief of Science and Technology of Britain's Met Office, Stephen Belcher, said that unless emissions were reduced, the country might experience similar heatwaves every three years.
Treasury Minister Simon Clarke said Tuesday's "remarkable, unprecedented" record served as "a reminder ... of the importance of tackling climate change."
British engineers raced on Wednesday to fix train tracks that buckled in the heat after firefighters worked through the night to damp down wildfires. On Tuesday, London firefighters endured their busiest day since World War Two.
'OUR GRANDCHILDREN WILL SUFFER'
The shift in climate is leading to more wildfires and will force France and the European Union to take "structural decisions...in the years to come", President Emmanuel Macron said on Wednesday.
In southern Europe, far larger wildfires continued to rage.
In Italy, emergency crews in Tuscany battled the Lucca wildfire, which forced around 500 people to evacuate as flames reached villages overnight and caused liquefied gas tanks to explode, the region's governor, Eugenio Giani, tweeted.
Another fire close to the border with Croatia and Slovenia forced state-owned shipbuilder Fincantieri to close down its plant in the port city of Monfalcone, which employs 3,000 people.
As the fire crossed into Slovenia, the mayor of nearby Trieste told local TV that parts of the town could soon stop receiving power, which would shut off the water supply.
In Greece, thick smoke darkened the sky over Mount Penteli, 27 km (16 miles) north of Athens, where close to 500 firefighters, 120 fire engines and 15 water-carrying planes managed to stem the spread of a wildfire.
"Yesterday's fire in the area of Penteli had all the features of a situation which was very hard to manage," Civil Protection Minister Christos Stylianides said in a televised statement later on Wednesday.
"Now the fire has been brought under control."
Greek authorities said they evacuated nine settlements and a hospital, and police helped at least 600 residents out of fire zones. Strong winds were forecast to persist in the area until Thursday.
In France, where firefighters in the southwestern Gironde region have been battling since July 12 to contain huge forest fires, Agriculture Minister Marc Fesneau said more money needed to be invested to tackle such threats.
In Portugal, as the Murça fire raged nearby, olive tree grower Manuel Lopes, 67, feared for his plantations and for the future of his drought-stricken region. "Our grandchildren ... will suffer if this (climate change) doesn't stop," he said.
(Reporting by Renee Maltezou, Angeliki Koutantou, Karolina Tagaris and Vassilis Triandafyllou in Athens; Dominique Vidalon, Mathieu Rosemain and Sudip Kar-Gupta in Paris; Kate Holton and William James in London, Emma Pinedo in Madrid and Catarina Demoney in Lisbon; Writing by John Stonestreet; Editing by Nick Macfie, Alex Richardson and Mark Heinrich)