No, Global Warming Hasn't 'Stopped'

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The headline was catnip to climate change deniers:

“Global Warming Stopped 16 Years Ago, Says Met Office Report Quietly Released.”

It hits all the right notes: Global warming is a myth; and ‘they’ know it’s a myth and are trying to keep it quiet. (The ‘they’ in this context – the Met Office – is Britain’s national weather forecasting service. Met is an abbreviation for Meteorological.)

The article, in the London tabloid Daily Mail, goes on to state: “The world stopped getting warmer almost 16 years ago, according to new data released last week. The figures, which have triggered debate among climate scientists, reveal that from the beginning of 1997 until August 2012, there was no discernible rise in aggregate global temperatures … The new data, compiled from more than 3,000 measuring points on land and sea, was issued quietly on the internet, without any media fanfare, and, until today, it has not been reported.”

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It is said that there is nothing new under the Sun, and the denialist argument that there has been no warming since 1997 or 1998 is an oft-repeated one. We’ve addressed it here several times, notably back in 2009 when ‘Washington Post’ columnist George Will was repeating it a great deal.

It seemed to, ahem, cool down a little when 2010 moved ahead of 1998 in the medal race for World’s Hottest Year – but, as John Cook of the excellent Skeptical Science blog said when I mentioned the Daily Mail article to him, “I fully expect to see this ‘global warming has stopped’ myth repeated for many years to come.” Indeed, David Rose, author of the ‘Daily Mail’ article, has been repeating that same line for some time himself.

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So what’s the story? It should first of all be pointed out that, contrary to the headline’s claims, the Met Office didn’t “quietly release” any report – it simply updated its ongoing temperature data set. It should also be pointed out that a scientist whom Rose quoted as saying that the news showed climate models are ‘deeply flawed’ in fact insists she said no such thing.

The key point here is in the arbitrary starting point. Climate scientists note that while the underlying long-term trend is unmistakable, it can be masked by short-term natural variations. And 1998 was an exceptionally hot year as a result of a very strong El Niño that created a lot of atmospheric warming. (In fact, it currently occupies the bronze medal position, behind 2005 and the race-leading 2010.) Move the starting point to 1999, and the picture changes considerably. 

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As the aforementioned Skeptical Science has observed, there’s a wrong way to look at long-term trends:

And there’s a right way:

In response to the ‘Daily Mail’ article, the Met Office posted a graph that includes a larger number of years and show the real trend quite clearly:

As can be seen, at first glance, the years seem to follow no discernible order: 2010, 2005, 1998, 2003, 2006. But the decades are color-coded, which shows that the vast majority of the hottest years are in this century, followed by the 1990s etc. As the Met Office pointed out in December 2009, “the first decade of this century has been, by far, the warmest decade on the instrumental record.”

The farther back in the instrument record one goes, the clearer the trend. Witness, for example, this graph, from last year:

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That graph is the work of the Berkeley Earth Surface Temperature (BEST) project, led by former climate skeptic - yes, skeptic – Richard Muller. As we noted last year, Muller was surprised to find that his own analysis of temperature data closely matched those of the scientists he had previously criticized. He wrote:

When we began our study, we felt that skeptics had raised legitimate issues, and we didn’t know what we’d find. Our results turned out to be close to those published by prior groups. We think that means that those groups had truly been very careful in their work, despite their inability to convince some skeptics of that. They managed to avoid bias in their data selection, homogenization and other corrections. Global warming is real. Perhaps our results will help cool this portion of the climate debate.

Alas, no. Global warming, unfortunately, has not stopped. But nor have the efforts of some to claim that it has.

IMAGES:

Top Photo: The glacier was here in 1992 reads a sign below the foot of Canada’s Athabasca Glacier. The present day terminus is visible in the background. Global warming has fast contributed to the demise of Athabasca and other glaciers around the world. (Ben Cooper, Corbis)

Top two graphs courtesy of Skeptical Science. Third graph courtesy of UK Met Office. Bottom graph by Berkeley Earth Surface Temperature (BEST) Study.