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Setting the stage for an intense debate, a new study has found that warming of American's west coast over the last century is a result of wind pattern changes and not human activity.

The Telegraph reported that temperatures on the west coast increased by one degree Celsius between 1900 and 2012, with 2014 set to top the temperature charts. However flying in the face of several studies that showed west coast's warming has anthropogenic origins, the new study shows that changes in wind circulation patterns caused temperatures to rise.

"Sea level pressure reductions and related atmospheric forcing led to century-long warming around the North-East (NE) Pacific margins, with the strongest trends observed from 1910-1920 to 1940. North-East Pacific circulation changes are estimated to account for more than 80% of the 1900-2012 warming in coastal NE Pacific sea surface temperature and US Pacific northwest (Washington, Oregon, and northern California) surface air temperature," researchers explained.  

As most warming happened before 1940 when greenhouse gas concentrations were small, the findings pose a strong arguement against man-made warming theories. 

"It was a big eye-opener. The winds have changed in a manner that explains virtually all of the coastal ocean warming. The winds appear to decide it all," study's lead author James Johnstone told The Seattle Times.

The study has evoked mixed responses from the scientific community as it flays long-held beliefs that human activity contributed to warming of the west coast.

"That sort of flies in the face of many, many years of research and modeling. That leads me to question whether or not the results are robust," said University of Idaho climatologist John Abatzoglou. He raised doubts over the accuracy of early-20 century data.

Johnstone and co-author Nate Mantua are however quick to point out their study does not rule out global warming happening in other parts of the world and the possibility that it could lead to future problems along the west coast.

The findings have been published in the Proceedings of National Academy of Sciences.