Date(s): February 26, 2009

Presenter(s): Nicola Scafetta (Duke University)

Description: A comparison of past and recent studies suggests that the problem of climate change is complex, as it is evident. Several key issues remain open and their solution may drastically change our understanding of the phenomenon. The crucial issue is: how is it possible to address a problem such a climate change where several crucial physical ingredients are still severely uncertain? In particular, some of the key issues he will address are: a) Did the total solar activity remain constant (as the IPCC and PMOD claim) or increase (as ACRIM claims) since 1980? b) Was the preindustrial temperature almost constant (The Hockey Stick graph) or did it experience a large change? c) What is the contribution of the GHG forcing on climate change, was it overestimated in some important past publications and might this have contributed to shape and bias the following debate? It is evident that solving the above issues in one way or in another is crucial for correctly interpreting climate change. He will propose a solution based on minimal physical assumptions that appear to have been confirmed by a large scientific empirical and theoretical literature. This solution suggests that a significant portion of climate change is natural and linked to changes of solar activity. He will also address the puzzling possibility that climate change might be partially driven by an additional natural forcing different from the radiative one that has not been identified yet. Finally, he will use these findings to attempt a climate prediction about the 21st century and discuss the possibility of an imminent global cooling.

Dr. Scafetta is a research scientist in the Department of Physics at Duke. He has about 40 papers in peer reviewed journals and two books in preparation.

Presentation Document: Climate Change and Its Causes: A Discussion about Some Key Issues

Seminar Category: Climate Science