We (Peter Langdon Ward and David Bennett Laing) have just published a new theory of global warming that better accounts for temperature change over the past 100 years and throughout the Phanerozoic Eon than the currently favored greenhouse warming theory. In view of the extreme difficulty in getting peer-reviewed journals to publish papers that run counter to greenhouse theory, we decided to present our concept in a semi-popular book, “What Really Causes Global Warming? Greenhouse Gases or Ozone Depletion?”. The book is available in hardback, paperback, and ebook versions on amazon.com (search for “what really causes”), and in most bookstores. We also have a website: whyclimatechanges.com.

In brief, we find that major temperature changes throughout Phanerozoic time can be fully explained with two different styles of volcanic eruption: effusive and explosive. It is well-known that aerosols from explosive volcanoes like Pinatubo reflect sunlight and cause global cooling. What we found is that all volcanoes emit chlorine and bromine (as HCl and HBr), which deplete the ozone layer, allowing increased irradiance of Earth by solar UV-B radiation, causing global warming. UV-B is 48 times more energy-rich than Earth’s IR radiation absorbed by carbon dioxide.

In the case of explosive volcanoes, the aerosol cooling effect overwhelms the warming effect from ozone depletion, but since effusive volcanoes don’t emit aerosols, warming prevails. Effusive eruptions are also much longer-lasting and can be extremely voluminous. Massive effusive eruptions in Iceland occurred precisely at the time when Earth warmed out of the last ice age. Less massive effusive eruptions coincided with every one of the numerous, enigmatic Dansgaard-Oeschger warming events during the ice age. Much more massive effusive eruptions accompanied extreme warming events during the Paleocene-Eocene Thermal Maximum, the End-Permian Extinction, the Cretaceous-Paleocene boundary, and many others throughout the Phanerozoic.

We view the dramatic warming event of the late 20th century as anthropogenic, but not due to carbon dioxide. The event coincided with the release of chlorofluorocarbon (CFC) gases to the atmosphere, which became photodissociated to release chlorine, thus mimicking the ozone depleting and global warming effects of effusive volcanism. The Montreal Protocol ended CFC production and thereby ended global warming, thus explaining the enigmatic “global warming hiatus” that has prevailed since 1998. No other convincing explanation for the “hiatus” has been proposed or generally agreed upon. A warming effect from the massive effusive eruption of Iceland’s Bardarbunga volcano in late 2014 and early 2015 will likely make 2015 the warmest year on record, but still nowhere near as warm as predicted by the greenhouse warming based climate models.

Global temperature has plateaued rather than fallen, and ice masses still continue to melt globally, because chlorine remains in the stratosphere and continues to destroy ozone catalytically. This will continue for several decades, and due to heat storage in the oceanic thermal reservoir, it is likely that eventual lowering of global temperature will have to depend on a series of explosive volcanic eruptions. Until (and if) these occur, it seems equally likely that we will simply have to adapt to a world that is about one Fahrenheit degree warmer than it was in the mid-20th century, but at least we shouldn’t have to worry about “climate Armageddon” due to further warming, as long as we remain vigilant against further releases of existing CFC stockpiles.

In the book, we also discuss the failings of greenhouse warming in considerable detail on both theoretical and observational grounds. An exhaustive literature search revealed that only one actual experiment has ever been performed to test greenhouse warming theory. It was done by Knut Angstrom in 1900, and he concluded that any warming effect from increasing atmospheric CO2 concentration was negligible. Accordingly, Peter Ward has issued a $10,000 challenge to anyone who can demonstrate by experiment that greenhouse gases are more effective at warming Earth than ozone depletion. To date, he has had no takers.

We would welcome your thoughts on the foregoing, especially if they follow a careful reading of the book.

David Bennett Laing