Oggi si legge. Due nuovi lavori di Nicola Scafetta, tornato ormai da un paio d’anni a lavorare in Italia, presso l’Università Federico II di Napoli. Entrambi i paper sono open source.
In pratica si tratta nel primo lavoro di un’analisi comparativa dei dati osservati con quanto previsto dai modelli climatici, analisi che giunge ad un verdetto che già conosciamo ma che molti sembrano voler ignorare: l’attuale capacità di riprodurre le dinamiche del clima è molto limitata; ne deriva una sostanziale sovrastima del contributo antropico al trend di riscaldamento osservato e una ancora più sostanziale inadeguatezza degli strumenti di proiezione ad essere utilizzati come riferimento per le policy in materia di clima e ambiente.
During the whole history of the planet, astronomical factors (orbital and solar variability) have determined the energy balance of the Earth and generated natural climate oscillations affecting the life of plants, animals and human beings at all time scales. During the last decades, severe concerns have been raised about whether human activities could have been so influential as to deeply modify the natural variability of the global climate and, in particular, could have caused a significant warming since the beginning of the 20th century. To properly address the latter issue, it is required to understand the phenomenology of the natural climate fluctuations. These are well emphasized by several climate indexes such as the Atlantic Multidecadal Oscillation, the Pacific Decadal Oscillation, the El Niño–Southern Oscillation and others. This complex natural dynamic is still not reproduced by the general circulation models (GCMs) supporting the Anthropogenic Global Warming Theory (AGWT), which is mainly advocated by the Intergovernmental Panel on Climate Change (IPCC). In this “part 1” of our work we briefly introduce the general topic and statistically compare observed and GCM modeled global surface warming trends from 1860 to 2016. We find that the models have significantly overestimated the observed warming during the historical record. In addition, we compare observed and modeled temperature trends of three significant periods: from Jan/1922 to Dec/1941, from Jan/1980 to Dec/1999 and from Jan/2000 to Dec/2016. We find that only during the 1980-1999 period the observed and synthetic records show compatible warming trends within the 95% confidence level. The severe discrepancy between observations and modeled predictions found during the 1922-1941 and 2000- 2016 periods further confirms, according to the criteria proposed by the AGWT advocates themselves, that the current climate models have significantly exaggerated the anthropogenic greenhouse warming effect.
Il secondo lavoro riprende un filone di ricerca già lungamente esplorato da Nicola Scafetta. Partendo dall’evidenza che, al netto del potente contributo di El Niño, il trend delle temperature medie globali continua ad essere molto distante da quanto prospettato dalle simulazioni, l’applicazione di un modello climatico semi-empirico basato su di uno specifico set di oscillazioni climatiche naturali e con un contributo antropico significativamente ridotto, restituisce risultati molto più soddisfacenti di quanto non facciano i modelli climatici tradizionali.
The period from 2000 to 2016 shows a modest warming trend that the advocates of the anthropogenic global warming theory have labeled as the “pause” or “hiatus.” These labels were chosen to indicate that the observed temperature standstill period results from an unforced internal fluctuation of the climate (e.g. by heat uptake of the deep ocean) that the computer climate models are claimed to occasionally reproduce without contradicting the anthropogenic global warming theory (AGWT) paradigm. In part 1 of this work, it was shown that the statistical analysis rejects such labels with a 95% confidence because the standstill period has lasted more than the 15 year period limit provided by the AGWT advocates themselves. Anyhow, the strong warming peak observed in 2015-2016, the “hottest year on record,” gave the impression that the temperature standstill stopped in 2014. Herein, the authors show that such a temperature peak is unrelated to anthropogenic forcing: it simply emerged from the natural fast fluctuations of the climate associated to the El Niño–Southern Oscillation (ENSO) phenomenon. By removing the ENSO signature, the authors show that the temperature trend from 2000 to 2016 clearly diverges from the general circulation model (GCM) simulations. Thus, the GCMs models used to support the AGWT are very likely flawed. By contrast, the semi-empirical climate models proposed in 2011 and 2013 by Scafetta, which are based on a specific set of natural climatic oscillations believed to be astronomically induced plus a significantly reduced anthropogenic contribution, agree far better with the latest observations.