Extremely hot temperatures over land have dramatically and unequivocally increased in number and area despite claims that the rise in global average temperatures has slowed over the past 10 to 20 years, according to scientists.
Scientists from the ARC Centre of Excellence for Climate System Science and international colleagues made the finding when they focused their research on the rise of temperatures at the extreme end of the spectrum where impacts are felt the most.
"It quickly became clear, the so-called "hiatus" in global average temperatures did not stop the rise in the number, intensity and area of extremely hot days" one of the paper's authors Dr Lisa Alexander, said.
"Our research has found a steep upward tendency in the temperatures and number of extremely hot days over land and the area they impact, despite the complete absence of a strong El Nino since 1998," she said.
The researchers examined the extreme end of the temperature spectrum because this is where global warming impacts are expected to occur first and are most clearly felt.
The observations also showed that extremely hot events are now affecting on average more than twice the area when compared to similar events 30 years ago.
To get their results, the researchers examined hot days starting from 1979. Temperatures of every day throughout the year were compared against temperatures on that exact same calendar day from 1979-2012. The hottest 10 percent of all days over that period were classified as hot temperature extremes.
Globally, on average regions normally expect around 36.5 extremely hot days in a year. The observations showed that during the period from 1997-2012, regions that experienced 10, 30 or 50 extremely hot days above this average saw the greatest upward trends in extreme hot days over time and the area they impacted.
The consistently upward trend persisted right through the "hiatus" period from 1998-2012.
