Dr. Roy Spencer in Helsinki
Recent satellite evidence shows that computer climate models project too much future warming according to Dr. Roy Spencer who gave the first talk at a yearly meeting of climate realists in Finland coordinated by Dr. Boris Winterhalter. Dr. Spencer is a resercher in meteorology and former Nasa climate scientist. He explained that climate models are thrown off by a small amount of warming which results when extra atmospheric carbon dioxide reduces cloud cover over the Earth. This amplifies the warming predicted by the models and is an example of “positive feedback.” In the 21 climate models tracked by the Intergovernmental Panel on Climate Change (IPCC) the differences in warming are mainly attributable to varying degrees of positive cloud feedback.
In contrast, data from NASA’s Terra and Aqua satellites over the period 2000 – 2007 shows strong negative cloud feedback. Dr. Spencer attributed the discrepancy between the models and observations to the the climate modelers failure to account for natural cloud variation which was shown to cause temperature change in previous satellite studies. In simple terms, the IPCC confused cause and effect in interpreting the co-variations between temperature and cloud cover.
These results, which have been submitted to the Journal of Geophysical Research for publication, suggest that increased CO2 is insufficient to explain global average warming during the last 50 to 100 years. Spencer offered an alternative explanation, that the Pacific decadal oscillation modulates global cloudiness by a small amount which changes approximately every 30 years and supported this with satellite evidence.
Discussion with attendees focused mainly on the possible role of solar variation in global warming. Spencer replied that solar activity might also be involved, and it is therefore increasingly obvious that there are many unanswered questions as to what truly causes climate change on decadal to centennial time scales. After the talk Dr. Spencer conducted an interview which aired on Finland’s national television along with taped portions of his presentation .