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"But it does not mean global warming is a delusion."

The fact is temperatures between 2000 and 2010 are still almost 1C above their level in the first decade of the 20th century.

"The mismatch might mean that for some unexplained reason there has been a temporary lag between more carbon dioxide and higher temperatures in 2000-2010.

"Or it might mean that the 1990s, when temperatures were rising fast, was the anomalous period."

The magazine explores a range of possible explanations including higher emissions of sulphur dioxide, the little understood impact of clouds and the circulation of heat into the deep ocean.

But it also points to an increasing body of research that suggests it may be that climate is responding to higher concentrations of atmospheric carbon dioxide in ways that had not been properly understood before.

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On face value, Hansen agrees the slowdown in global temperature rises can be seen as "good news".

But he is not ready to recalculate the Faustian bargain that weighs the future cost to humanity of continued carbon dioxide emissions.

Hansen argues that the impact of human carbon dioxide emissions has been masked by the sharp increase in coal use, primarily in China and India.

Increased particulate and nitrogen pollution has worked in the opposite direction of rising carbon dioxide levels in the atmosphere.

Another paper published in Geophysical Research Letters on research from the University of Colorado Boulder found small volcanoes, not more coal power stations in China, were responsible for the slowdown in global warming.

But this did not mean that climate change was not a problem.

"Emissions from volcanic gases go up and down, helping to cool or heat the planet, while greenhouse gases from human activity just continue to go up," author Ryan Neely says.

Hansen's bottom line is that increased short-term masking of greenhouse gas warming by fossil fuel particulate and nitrogen pollution represents a "doubling down" of the Faustian bargain, an increase in the stakes.

"The more we allow the Faustian debt to build, the more unmanageable the eventual consequences will be," he says.

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