Study: global warming ‘pause’ caused by natural climate cycles

The so-called global warming ‘pause’ in recent years is likely to have been caused by natural variations in the climate cycle, not a slowdown in man-made climate change, according to a team of scientist.

The research, which has been published in Science, notes the importance of ensuring that studies highlight the difference between man-made climate change and changes that occur naturally.

Michael Mann, a professor of Meteorology at Penn State University, US, and one of the researchers, said, “We know that it is important to distinguish between human caused and natural climate variability so we can assess the impact of human-caused climate change on a variety of phenomena including drought and weather extremes.

“The North Atlantic and North Pacific oceans appear to be drivers of substantial natural, internal climate variability on timescales of decades.”

The study involved looking at a combination of real world observational data and state-of-the-art climate model simulations used in the most recent report of the Intergovernmental Panel on Climate Change to understand the competing contributions to climate variability.

The paper explains that natural cycles in the Pacific and Atlantic have caused an overall cooling effect on temperatures, masking the full impact on manmade climate change.  The researchers conclude that given past historical variations, the global warming ‘pause’ will likely reverse and add to human-induced warming in the future.

Mann added, “Our findings have strong implications for the attribution of recent climate changes. Internal multidecadal variability in Northern Hemisphere temperatures likely offset anthropogenic warming over the past decade.”

Several other pieces of research have suggested why the ‘pause’ in global warming has occurred, including gaps in data, the use of older technology and cooler Pacific temperatures.

Photo: Liam Quinn via Flickr

Further reading:

‘Pause’ in global warming a result of gaps in data, finds new research

The Economist: global warming ‘pause’ goes from ‘unexplained to overexplained’

Modern technology could have predicted global warming hiatus

Cooler Pacific temperatures explain slowdown in global warming