A new study finds no link between incoming cosmic rays, global cloud cover and global warming, dealing another setback to those who claim climate change is triggered by cosmic rays rather than manmade greenhouse gases.

The research was led by Terry Sloan of Lancaster University in the UK and Arnold Wolfendale of Durham University, also in the UK.

"If the effect were important, then we would have seen it," Rasmus Benestad of the Norwegian Meterological Institute told LiveScience. "[Cosmic rays] cannot account for the present warming trend."

Some skeptics have argued that changes in solar activity are responsible for the current period of warming. They argue that the sun's magnetic fields cause fluctuations in the intensity of cosmic rays, which they contend can ionize gases in Earth's atmosphere, creating small particles that collect water to form low-level clouds. These clouds, in turn, scatter incoming light, causing a cooling effect.

Among the skeptics, a small group of scientists say it is a decrease in cosmic rays that has decreased the amount of low-level clouds, causing the current phase of warming. A recent British television special, "The Great Global Warming Swindle," which aimed to debunk current scientific understanding of the causes of global warming, named this as the main cause of Earth's rising temperatures.

But the new study found no significant link between the intensity of cosmic rays hitting the Earth and low-level cloudiness. Its findings "suggest that it is fairly unlikely that [cosmic rays] have any discernable effect on the cloudiness," said Benestad, who was not involved with the study.

Benestad also pointed out that no long-term trend in cosmic ray intensity that corresponds with the decades-long rise in global temperatures has been detected, which is a bigger stumbling block for those who support cosmic rays as the source of global warming.