A heat wave is sweeping Europe with temperatures in normally cool Britain exceeding those on the Mediterranean coast. Britain's weather forecasting service the Met Office said that there is a chance the country will record its highest temperature of all time on Wednesday -- previously 38.5 degrees Celsius (101.3 Fahrenheit) recorded in Kent, south-east England in August 2003.

There were reports of asphalt on roads melting and railway tracks buckling in the extreme heat. London Underground passengers had to endure temperatures of up to 47 degrees Celsius (117 Fahrenheit) Monday as there is no air conditioning on London's transport system. London's mayor even warned that parts of the underground may have to be closed in the future as the sweltering heat posed a serious risk of death to passengers should a train break down during the hot weather and commuters become trapped in a furnace-like tunnel.

Across Europe there have been similar problems and warnings as temperatures soar way above the seasonal average. In Germany temperatures could reach 38 degrees Celsius (100 Fahrenheit) on Thursday in parts of the country. Emergency services are reporting a 20 percent increase in calls. The heat wave has already recorded its first casualties, with six deaths across the continent in the past few days attributed to excessive temperatures. In the southern French city of Bordeaux, authorities on Tuesday confirmed the deaths of two elderly people due to the heat. An 85-year-old man died on arrival in hospital and an 81-year-old woman was found dead in her apartment. In the Netherlands two members of a hiking event fell victim to the heat in temperatures touching 34 degrees Celsius (93 Fahrenheit). Thirty people were also taken to hospital suffering from heat stroke. In Spain, two workers collapsed and died after working in the blistering heat, where temperatures reached 41.5 degrees Celsius (107 Fahrenheit).

European governments have issued health warnings and placed medical workers on high alert after a heat wave in 2003 killed 27,000 people across the continent, many of whom were elderly or infirm. French Heath Minister Xavier Bertrand called for increased vigilance during the hot spell as the country was placed on "orange" alert, the third-highest temperature warning level. Britain's Department of Heath said, "These temperatures are high enough to give rise to significant health risks."

Britain's meteorological office issued a statement claiming there was a "significant human contribution" towards recent heat waves due to carbon dioxide emissions. "This is a sign of things to come, with the current temperatures becoming a normal event by the middle of the century." Hervé Le Treut, the head of the weather research unit at science research center CNRS in Paris, told the AFP news agency. "Climate change has begun -- there's no doubt we're reached the start of the process."