In a highly controversial paper, climate scientists at three US universities have contested claims that greenhouse gases were causing climate change and instead attributed it to earth's "natural cycle."

The scientists at the University of Rochester, the University of Alabama, and the University of Virginia have said that the observed patterns of temperature changes over the last 30 years are not in accord with what greenhouse models predict.

These observations are in conflict with the conclusions of the United Nations Intergovernmental Panel on Climate Change (IPCC) and also with some recent research publications based on essentially the same data.

However, they are supported by the results of the US-sponsored Climate Change Science Program (CCSP).