New Study: Global Warming Standstill Confirmed, Climate Models Wrong

Earth and climate – an ongoing controversy

A new study by Nicola Scafetta and colleagues is featured at The Global Warming Policy Forum (GWPF).

ABSTRACT 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.

INTRODUCTION As explained in part 1 of this study [1], in the last decade future climate scenarios have been used to develop and politically enforce energy expensive policies to contrast catastrophic climate warming expectations for the 21st century. This has been done mostly by the United Nations Intergovernmental Panel on Climate Change [2, 3, 4]. Several studies based on general circulation model (GCM) simulations of the Earth’s climate concluded that the 20th century climate warming and its future development depend almost completely on anthropogenic activities. Humans have been responsible of emitting in the atmosphere large amount of greenhouse gases (GHG) such as CO2 throughout the combustion of fossil fuels. This paradigm is known as the Anthropogenic Global Warming Theory (AGWT).

However, before trusting GCM projections about future climatic changes, it is necessary to validate these models by testing whether they are able to properly reconstruct past climate changes. In Ref. [1], the authors have argued that since 2001 AGWT was actually supported by the belief that the “hockey stick” proxy temperature reconstructions, which claim that an unprecedented warming occurred since 1900 in the Northern Hemisphere, were reliable [2,5] and could be considered an indirect validation of the available climate models supporting the AGWT [6].

However, since 2005 novel proxy temperature reconstructions questioned the reliability of such hockey stick trends by demonstrating the existence of a large millennial climatic oscillation [7-10]. This natural climatic variability is confirmed by historical inferences [11] and by climate proxy reconstructions spanning the entire Holocene [12, 13]. A millennial climatic oscillation would suggest that a significant percentage of the warming observed since 1850 could simply be a recovery from the Little Ice Age of the 14th – 18th centuries and that throughout the 20th century the climate naturally returned to a warm phase as it happened during the Roman and the Medieval warm periods [9, 11, 14- 16].

Continued here.

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