The paper, by climate change contrarians John McLean and Associate Professor Bob Carter of the Australian Climate Science Coalition and New Zealand climate scientist Associate Professor Chris de Freitas, describes a close link between the Southern Oscillation Index (SOI) and the temperature of the troposphere, the lower 17-20km of the Earth's atmosphere.

The authors establish that tropospheric temperatures respond to changes in the SOI after a lag of 5-7 months.

They argue that analysis of this link demonstrates that most of the warming—about 70 per cent—observed over the past 50 years can be attributed to the SOI.

"… this study has shown that natural climate forcing associated with ENSO is a major contributor to variability and perhaps recent trends in global temperature, a relationship that is not included in current global climate models," the authors concluded.

The peer-reviewed paper was published on July 23 in the respected Journal of Geophysical Research (JGR).

The paper, and the claims made within and about it, are likely to stir up strong debate in the scientific community, as appears to be the authors' intention.

In a press release issued by the Australian Climate Science Coalition this week, the authors cast aside scientific moderation and take a more direct political line.

"Our paper confirms what many scientists already know: which is that no scientific justification exists for emissions regulation, and that, irrespective of the severity of the cuts proposed, an emissions trading scheme will exert no measurable effect on future climate," said Prof. Carter, one of Australia’s most prominent dissenters against the theory of human-induced global warming.

"The close relationship between the Southern Oscillation and mean global temperature, as described in the paper, suggests future global temperatures will continue to change primarily in response to ENSO cycling, volcanic activity and solar changes."