The Shifts Hypothesis - an alternative view of global climate change

Abstract

In this study we used HadCRUT4 temperature anomalies for 1950-2013 years in order to investigate properties of recent warming. Our aim was to separate changes produced by short-term ENSO variations and to look on temporal and spatial dynamics of residual temperature anomalies. For this we subtract linear influence of ENSO index from each HadCRUT4 grid box. We found that residual global temperature dynamics looks like staircase function: linear trends for three quasi-stable periods 1950-1987, 1988-1997 and 1998-2013 are near zero and near all warming occurred during two shifts of 1987/1988 and 1997/1998 years. All these allows us to formulate a new hypothesis about recent warming - the Shifts Hypothesis. It explains the structure of recent warming as follows: during shifts of 1987/1988 and 1997/1998 the mean value of global temperature quickly rose, over which natural variability associated with ENSO, PDO and many other local factors occurs. According to IPCC forcing-response paradigm warming process (WP) cleared from all factors should be continuous warming (may be near linear on the considered time interval). This idea is inconsistent to the obtained staircase function. This staircase function may be explained by current IPCC forcing-response paradigm only if it happened so that the combination of compensating factors is near the same as anthropogenic greenhouse gases (GHGs) forcing for each quasi-stable period - 1950-1987, 1988-1997 and 1998-2013. This seems very unlikely. An alternative and more simple explanation is the existence of some regulation mechanism (e.g. global thermostat) not presented in IPCC climate models. This mechanism should maintain global temperature near stable in 1950-1987, 1988-1997 and 1998-2013 periods nevertheless all the time growing forcing due to anthropogenic GHGs.