Earth climate identification vs. anthropic global warming attribution

Based on numerical models and climate observations over past centuries, the Intergovernmental Panel on Climate Change (IPCC) attributes to human activity most of the warming observed since the mid-20th century. In this context, this paper presents the first major attempt for climate system identification - in the sense of the systems theory - in the hope to significantly reduce the uncertainty ranges. Actually, climatic data being what they are, the identified models only partially fulfill this expectation. Nevertheless, despite the dispersion of the identified parameters and of the induced simulations, one can draw robust conclusions which turn out to be incompatible with those of the IPCC: the natural contributions (solar activity and internal variability) could in fact be predominant in the recent warming. We then confront our work with the approach favored by IPCC, namely the “detection and attribution related to anthropic climate change”. We explain the differences first by the exclusion by IPCC of the millennial paleoclimatic data, secondly by an obvious confusion between cause and effect, when the El Niño index is involved in detection and attribution.