Guest blog by Dr. Anthony Lupo, University of Missouri

A recent paper published in the Geophysical Research Letters deserves some attention, not only for the work done, but the implications of the paper as well. The paper, “A new dynamical mechanism for major climate shifts”, by A.A. Tsonis, K. Swanson, and S. Kravtsov is remarkable because it brings back some common sense in the climate change debate. This paper discusses the collective behavior of four major climate “cycles” or variations and how they may interact with each other to impact the overall direction of climate or climate change. Some of these cycles are well-known to the public, such as El Nino or the North Atlantic Oscillation, and others are less known such as the Pacific Decadal Oscillation.

The authors can account for the warming and cooling periods of the 20th century by examining the dynamic behavior of these climate variations. In particular, they find that the climate regime can shift when these four cycles “synchronize”. Thus, they find that climate can shift, or change, due to internal (non-linear) climate dynamics, and they don’t even have to invoke an external climate change mechanism such as solar forcing. This is new and exciting work.

Thus, the paper cited above is a welcome message and is message that, while not exactly new, must be repeated over and over again even if the message is presented in different ways. Others, including many climate experts on this website have delivered a similar message. For example, a document authored by J. D’Aleo and G. Taylor present observed global temperature trends and demonstrate the same type climatic behavior that Tsonis et al. (2007) show can now be modeled.

Additionally, other studies including some published by my own research group demonstrates that changes in the frequency and intensity of natural cycles (such El Nino) can be modulated by other natural cycles (such as the Pacific Decadal Oscillation) and that the impact on the variations in local climates can be profound.  Read more here.