David Whitehouse

Between the start of 1997 and the end of 2014, average global surface temperature stalled. This 18-year period is known as the global warming pause, also sometimes referred to as the global warming hiatus. The rise in global temperatures that alarmed climate campaigners in the 1990s had slowed so much that the trend was no longer statistically significant. It has been the subject of much research and debate in peer-reviewed scientific journals. [caption id="attachment_9890412" align="alignnone" width="620"] Global surface temperature between January 1997 and December 2014[/caption] Then, in the spring of 2015, El Niño, a warm ocean phase in the equatorial Pacific developed. It rapidly drove up global temperatures by 0.5°C in less than a year.

The global warming 'pause' never existed, say the headlines. It's a claim that has been made before, only to be refuted, yet now it's back again. If there is one topic that sends a small subset of climate scientists' temperature into the stratosphere, it's the topic of the global warming 'pause' or 'hiatus'. This is the idea that global surface temperatures haven't changed much for almost 20 years. Never in my experience of science have I come across a topic like it, and that's because it means nothing, and everything. Global warming is about energy imbalance. Greenhouse gasses stop heat leaving the earth, so the planet is getting warmer. This is fundamental physics. Temperature goes up; oceans warm up, expand and sea level rises; pole caps melt.

If you happened to be standing today on the reddish sand of Meridiani Planum - a vast, flat, expanse just south of the Martian equator - you might well spot a dark spec in the distance against the peach-coloured sky, moving towards you. In the next few hours, the European Space Agency's Schiaparelli probe will make its final, six-minute decent through the Martian atmosphere. If it succeeds in touching down safely, the probe will be one of the very few to make it to the Martian surface. But after a journey of 500 million kilometres, it's only then that the probe's work will really start: scientists hope the Schiaparelli lander will act as a Martian weather station, sending data all the way back to earth in preparation for a future, more ambitious probe.

This article, in Nature magazine, ought to have been front page news - and might have been, had it suggested that global warming was worse than we had thought.  Instead, it underlines the sound science behind an inconvenient truth: that there has been a 15-year hiatus in global warming. To those of us who have been following the debate, this is no surprise. In 2007 I pointed out that it was curious that in recent years the global annual average temperature had not increased at a time when greenhouse gasses were increasing rapidly and when the media was full of claims that the earth's temperature was getting higher and higher. I proposed no explanation but said that it was a curious observation that would probably change in the near future.

Some people find climate change ‘deniers’ the most irritating people on God's green earth. On her Telegraph blog Martha Gill equates them with flat-earthers, which says a lot for the depth of her analysis. She points to a piece on the Huffington Post by Bob Ward of the Grantham Research Institute on Climate Change and the Environment (funded by billionaire Greenpeace contributor Jeremy Grantham, who also sponsors an $80,000 prize for environmental reporting – which this article will stand no chance of winning) and says it demolishes the deniers’ arguments. The problem is that it doesn't. Those who think ‘deniers’ are a problem and seek to put them down are in doing so misrepresenting the science they want to uphold.