These empirical results suggest that overly pessimistic predictions of global warming precede large falls in global temperature. Thus, the level of alarmist sentiment has the potential to be a useful predictor of global temperatures. The rational null expectations hypothesis is tested against the alternative hypothesis that extremes of sentiment signal turning points in global temperature.


Sentiment models are based on the idea that extreme sentiment levels signal turning points. These points occur at rare times, when irrational emotional responses lead to temporary extremes that are unsustainable. If you are indeed near the peak of an extreme, it is more likely that levels will fall away, thus contradicting the extremes up to and at the peak. Being aware of sentiment models can help you identify when levels of sentiment are at unrealistic, alarmist extremes.

The figure below shows the correspondence between landmark studies in global warming in the last 10 years and sudden falls in global temperatures. The first and largest fall was after the publication in 1998 by Mann et al. of the (now discredited) Hockey Stick showing temperatures flat for the last 1000 years and suddenly spiking up in the 20th century. The start of the most recent fall in temperature coincides with the 4 May 2007 publication by Rahmstorf et al. (Science Brevia) concluding that “The climate may be responding faster than IPCC models suggest”. The onset of other major falls in the last ten years is marked by other landmark studies in climate alarmism. The publications numbered in the figure are listed below.


Figure: Dates of publications indicating extremes of global warming sentiment precede sudden falls in global temperature (UAH MSU for lower troposphere).

1. April 1998 Paleoclimatology

Global-scale temperature patterns and climate forcing over the past six centuries“, by Michael E. Mann, Raymond S. Bradley & Malcolm K. Hughes. The origin of the famous hockey stick graph claiming temperatures are the highest experienced in 600 (and then 1000) years. The view has been reversed by a number of more rigorous studies.

2. January 2004 Biodiversity

Extinction Risk from Climate Change,” by Chris D. Thomas, Alison Cameron, Rhys E. Green, Michel Bakkenes, Linda J. Beaumont, Yvonne C. Collingham, Barend F. N. Erasmus, Marinez Ferreira de Siqueira, Alan Grainger, Lee Hannah, Lesley Hughes, Brian Huntley, Albert S. van Jaarsveld, Guy F. Midgley, Lera Miles, Miguel A. Ortega-Huerta, A. Townsend Peterson, Oliver L. Phillips8 & Stephen E. Williams, Nature, stating “we predict, on the basis of mid-range climate-warming scenarios for 2050, that 15–37% of species in our sample of regions and taxa will be ‘committed to extinction’.”

2004 has been described as the year global warming got respect. A number of significant reports of alarmist sentiment appeared throughout the year (as temperatures plummeted) including the Climate Impact Assessment (ACIA) report by an international team of 300 researchers for the Arctic Council, predicting the Arctic will lose 50% to 60% of its ice distribution (ice extent has since returned to long term averages). In December “The Scientific Consensus on Climate Change” by Nancy Oreskes found of papers published between 1993 and 2003 with the words “global climate change” in their abstracts that “Not one of the papers refuted the claim that human activities are affecting Earth’s climate”.

3. May 2006 Hollywood

The movie An Inconvenient Truth by Al Gore released
(soon as an opera).

4. May 2007 Global Climate Models

“Recent Climate Observations Compared to Projections” by Stefan Rahmstorf, Anny Cazenave, John A. Church, James E. Hansen, Ralph F. Keeling, David E. Parker, and Richard C. J. Somerville expressed the view that the IPCC (the consensus view on climate change) was too conservative and that “The climate may be responding faster than our current generation of models suggest” (temperatures have plummeted once again).


With a rational expectation of no bias, publications marking extremes of sentiment would be correct half of the time. The probability of the four publications would precede large falls in temperatures is 0.5×0.5×0.5×0.5=0.0625 or 6.25%. The null hypothesis is thus rejected at the 90% level but not at the 95% level. It is thus ‘very likely’ (according to IPCC terminology) that extremes of global warming sentiment mark turning points in global temperatures. Further work on development of an index of extreme global warming sentiment is in progress, and would be an important contribution to the emerging science of global warming error theory.

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