AGW reassessment through behavioral modeling from millennial climate data

Abstract

AbstractContext. Theanthropogenic principle, usually referred to as AGW (Anthropogenic Global Warming), is based on thousands of climate simulations that indicate that human activity is virtually solely responsible for the recent global warming. The climate models used are derived from the meteorological models used for short-term predictions. They are based on the fundamental and empirical physical laws that govern the myriad of atmospheric and oceanic cells integrated by the finite element technique. Numerical approximations, empiricism and the inherent chaos of fluid circulations make these models questionable for validating the anthropogenic principle, given the accuracy required (better than one per thousand) in determining the Earth energy balance.Aims.The objective is to quantify and simulate behavioral models of weak complexity, without explicitly referring to the parameters of underlying physical laws, but relying exclusively on generally accepted historical and paleoclimate series.Results. These models perform global temperature simulations that are consistent with those from the more complex physical models. However, the repartition of contributions in the current warming depends strongly on the retained temperature reconstructions, in particular the magnitudes of the Medieval Climate Anomaly and the Little Ice Age. It also depends on the level of solar activity series. It follows from these observations and climate reconstructions that the anthropogenic principle holds only for climate profiles assuming the absence of any significantPreindustrial Climate Oscillation(PCO) and variations in solar activity. Otherwise, it reduces to a weak principle where global warming is not only the result of human activity, but is largely due to solar activity.