Summer heatwaves are defined as having temperatures of 1.6 ºC or 33.9 ºF over the long-term average set between 1961 and 1990, while extreme heatwaves are 2.3 ºC or 36.1 ºF above the said average.

According to Dr. Nikos Christidis, the study’s lead author, extremely hot summers that were once expected to happen twice in a century during the early 2000s are highly likely to occur more frequently now. How frequently? Expect extremely hot summers about twice every 10 years.

“Moreover, the chances of heatwaves as extreme as seen in 2003 have increased from about 1-in-1000 to about 1-in100 years and are projected to occur once every other year by the 2030s-2040s under continuing greenhouse gas emissions,” Dr. Christidis added.

As the climate grows warmer, heatwaves increase in intensity and frequency, a fact that the new study supports.

The sharp spike in the chances that summer heatwaves in the region would occur in the last 10 to 15 years shows that increases in temperature are quickly affecting the likelihood of such events.

Dr. Peter Stott, a co-author for the study, said that updated projections for changes in the future show that by the time the century ends, summers will be so hot that the 2003 heatwave will be considered cool.

Stott also led a 2004 study that came up with the conclusion that man-made global warming doubled the risks of extreme heatwaves like the one Europe went through in 2003. That heatwave was believed to be the worst in 500 years, killing around 70,000 people. France was the hardest hit at the time.

The United Nation’s weather agency has said that the world’s temperature for 2014 is on track to be one of the warmest, if not the hottest, ever recorded.