Rome: As large parts of Europe and North America once again bake in an exceptionally hot summer, many people are asking what has now become a perennial question: "Is this global warming?"
The heat has already killed at least 21 people in France, including a 15-month-old baby, prompting fears of a repeat of the European heat wave in 2003 in which at least 15,000 people in France and 20,000 in Italy died.
Large parts of the United States and Canada have also seen record high temperatures this month.
"We are cooking," said US meteorologist Dennis Feltgen of the National Weather Service.
Many scientists reckon the globe is warming and will continue to do so due to the "greenhouse effect" caused by emissions from fossil fuels trapping heat in the atmosphere. But they say we should not read too much into a single hot spell.
"As ever, you cannot say any one weather event is caused by global warming," said Asher Timms of Britain's Tyndall Centre for Climate Change Research.
"But globally, it seems that there's quite a shift in our weather patterns."
Sceptics of the global warming theory, which predicts droughts and floods this century unless greenhouse gas emissions are curbed, say the media play up hot summer days for dramatic effect.
Bill O'Keefe, a board member of Washington think tank the George C. Marshall Institute and a consultant to the oil industry, said the record heat could be seen as part of a natural cycle of highs and lows.
"[Only] if this persisted for a very long time than you might be able to conclude that human activities had an impact," he said
But many scientists say a warming trend is already clear.
US space agency Nasa says 2005 was the warmest globally in more than a century and that the preceding three years were also the warmest since the 1890s.
