Steffen says quantifying the relative contributions of El Niño and climate change on a monthly or even annual basis cannot help to answer how fast the world is warming. Only trends over 30 years really matter.
But the pile up of records we have had in the early part of this century are significant. All things being constant, record hot years should occur once every 150 years. Yet 1998, 2005, 2010, 2014 and 2015 have all been record breakers.
A study published in January found that even without last year’s mammoth anomaly such a run was 600 to 130,000 times more likely to have occurred with human interference than without.
“The fact that you are getting records so close, one after the other is really striking. And that is symptomatic of that long-term trend,” said Steffen.
But while they may be poor signals for long-term climate change, record hot months and years do have an immediate and tangible impact.
“It’s making heat waves worse. Here in Australia it bumps up the bushfire danger weather really fast. It tends to lead to drier conditions in our part of the world. These things are exacerbated by El Niños, so I don’t want to downplay the importance of them for human suffering,” said Steffen.