Human-caused warming increased likelihood of record hot years

Human-caused global warming is significantly increasing the rate at which hot temperature records are being broken around the world, a study has found.
Global annual temperature records show there were 17 record hot years from 1861 to 2005.
Researchers at University of Melbourne in Australia examined whether these temperature records are being broken more often and if so, whether human-caused global warming is to blame.
The results show human influence has greatly increased the likelihood of record-breaking hot years occurring on a global scale.
Without human-caused climate change, there should only have been an average of seven record hot years from 1861 to 2005, not 17, researchers said.

Human-caused climate change at least doubled the odds of having a record-breaking hot year from 1926 to 1945 and from 1967 onwards, according to the study.

The study also projects that if greenhouse gas emissions remain high, the chance of seeing new global temperature records will continue to increase.
By 2100, every other year will be a record breaker, on average, according to the study published in the journal Earth's Future.
The new findings show how climate change is visibly influencing Earth's temperature, said Andrew King, a research fellow at the University of Melbourne.
"We can now specifically say climate change is increasing the chance of observing a new temperature record each year," said King, lead author of the study.

"It is important to point out we should not be seeing these records if human activity were not contributing to global warming," said King.
The study strengthens the link between human activity and recent temperature trends, according to Michael Mann, a climatologist at Pennsylvania State University in the US.
"This work builds on previous research establishing that, without a doubt, the record warmth we are seeing cannot be explained without accounting for the impact of human activity on the warming of the planet," Mann said.
Record hot years have been occurring more frequently in recent decades. 2014 was the hottest year on record since 1880, but that record was quickly broken in 2015 and again in 2016.

Research published earlier this year in the journal Geophysical Research Letters found these three consecutive records in global temperatures were very likely due to anthropogenic warming.
In the new study, King developed a method to isolate the human role in changing rates of record-breaking temperatures globally.
Unlike previous studies, the method uses a single source of temperature data, in this case global annual temperatures, allowing King to study temperature records on a global scale.
King first looked at global temperature data from 1861 to 2005 and identified which years were hot record breakers. He then used a wide array of climate models to simulate global temperatures in this period.