In the run up to the crucial climate conference in Copenhagen, and impending legislation on CO2 in the US congress, the sceptics are planning one final fight on the science of climate change.

Next month the right wing think tank, the heartland Institute, will host the “Third International Conference on Climate Change” in Washington. Make no mistake this is not a credible or international conference.

This will be yet another love-fest of the dying breed of the sceptics, funded by the right-wing think tanks that have tried to distort climate science for a decade.

It comes just three months after Heartland held the second “International Conference on Climate”. They are desperate for their voices to be heard, but like those who used to say the earth is flat, they belong to a by-gone age.

Once again the speakers will say that climate change is not man-made, and is caused by variation in the sun’s rays. Well new research should finally once and for all shut them up. Two scientists have developed a model to test a controversial hypothesis that says changes in the sun are causing global warming.

The hypothesis they tested was that increased solar activity reduces cloudiness by changing cosmic rays. So, when clouds decrease, more sunlight is let in, causing the earth to warm. In research published in Geophysical Research Letters, Adams and Pierce report the first atmospheric simulations of changes in atmospheric ions and particle formation resulting from variations in the sun and cosmic rays. They find that changes in the concentration of particles that affect clouds are 100 times too small to affect the climate.

“Until now, proponents of this hypothesis could assert that the sun may be causing global warming because no one had a computer model to really test the claims,” said Adams, a professor of civil and environmental engineering at Carnegie Mellon.

“The basic problem with the hypothesis is that solar variations probably change new particle formation rates by less than 30 percent in the atmosphere. Also, these particles are extremely small and need to grow before they can affect clouds. Most do not survive to do so,” Adams said. “Proponents of the cosmic ray hypothesis will probably try to question these results, but the effect is so weak in our model that it is hard for us to see this basic result changing.”

Time for the sceptics to sail off into the sunset then….