Here I have started to explore a new theory of global warming, not from greenhouse gas buildup in the troposphere, but from changes in stratospheric temperature caused largely by ultra-Plinian (stratosphere reaching) eruptions. A brief article entitled A Stratospheric Compensation Model of Climate Change, is in the May 8 issue of Australian Institute of Geologists Newsletter, pages 12-13.
The main lines of evidence presented for this theory are:
1. A correlation between the inverse of the global mean stratosphere and surface temperatures. This is illustrated in the figure below, showing both the short term cooling of the surface after sudden warming of the stratosphere due to two large eruptions, El ChichÃ³n (Mexico 1982) and Mt Pinatubo (Philippines 1991), and an apparent longer term warming with a delay as shown by the smoothed lines.
Figure: Monthly global surface (HadCRU in gray) and inverted stratosphere (-0.9*TLS in black) temperatures. Smoothed temperatures illustrate the correlation and potential stratospheric cause of recent surface temperature changes.
The warming after these volcanoes is usually attributed to two El Ninos, with no plausible causal mechanism, however I have seen the increased probability of El Ninos after large eruptions occasionally mentioned in the volcanism literature, (see here).
2. Theoretical support for the stratospheric origin of surface temperature changes from Miskolczi’s semi-transparent model of atmosphere. He has an equation, stratospheric compensation, that suggests an inverse delta between the stratosphere and the surface.
The idea is (but I don’t know what Miskolczi thinks about it) that while the temperature of the troposphere is constrained (due to optimization of greenhouse effect), the temperature of the stratosphere and surface can pivot in a see-saw motion while maintaining the same overall energy output of the planet as a whole. This is illustrated in the figure below, and contrasted with the tropospheric theory of warming.
Figure from Douglass et al. 2007 “A comparison of tropical temperature trends with model predictions” annotated to compare forcing of the GHG theory (red arrow) and stratospheric compensation theory (blue arrows).
3. Other back of envelope calculations to show that the major asymmetries of temperatures, between the Northern and Southern Hemispheres, and the glacial-interglacial periods, are possible without recourse to warming by troposphere greenhouse gases. Here I look at changes in albedo and emissivity that would be needed and if they are possible.
This is an exploratory article, based on some calculations to verify that such a theory is workable. I have since developed a more detailed model that I am presently writing up. It is taking somewhat longer than I had hoped, but in a few weeks I hope to have the basis of a comprehensive volcanic theory of climate change in place. What seemed at first to be an intriguing possibility, is actually looking interesting.
Predictions of the trajectory of temperature in the future from the stratospheric compensation model are:
“Baring major eruptions that produce immediate (~2yr) cooling and longer term warming, surface temperatures will gradually return to pre-CFC 1970 levels (-0.6K) depending on the pace of recovery of the ozone layer.”