Geoscientist Online

Dear Editor, The recent Soapbox piece by Martin Lack (Join the decarbonisation bandwagon, Geoscientist 29 (3), 9, April 2019) is a disturbing use of the good offices of the Geological Society to promote the objectives of an external organisation, particularly one based on the hypothesis that climate change is caused by human activities.

As geologists, we are all familiar with the concept of the Earth’s changing climate, which has gone on since the planet was born. The proposition, by supporters of the Anthropogenic Global Warming (AGW) hypothesis, that increasing quantities of CO₂ in the atmosphere have any significant influence on temperatures is very dubious. It can be shown that at present levels of CO₂ in the atmosphere, approximately 90% of the infra-red radiation (IRR) wavelengths affected by the gas have been attenuated. Even in the unlikely event that the increase in CO₂ since 1910 (from 210ppm to 414ppm now) has caused all of the warming (1.2 degrees) in that interval, absorption of the remaining 10% IRR will cause a temperature rise of 0.25 degrees. Beyond that point, further increases in CO₂ have no effect on IRR, or temperature.

The alarmist pronouncements by the IPCC that there are less than 12 years to go before climate change leads to the extinction of the majority of species of life on Earth are simply nonsense. It would be irresponsible for us geologists to support this idea—temperatures in the previous interglacial periods were between 0.5 and 1.5 degrees higher than at present. Similar fear-mongering prophesies have been made since the 1980’s, by the IPCC and others (Al Gore, for one); as with other predictions by the IPCC, they have not occurred.

The IPCC models forecast/hindcast neither the decline in global temperatures over the last two years, the unchanged temperatures between 2001 and 2013, nor the temperature decrease from 1950 until 1975. In all, their model has failed to match rates of temperature change for 57% of the time since consistent measurements of CO2 levels have shown a continuous rise; this outcome is deplorable—clearly other factors must contribute to climate change. A model, ignoring CO₂, but based on summing cyclical changes in temperature from 1860, and incorporating a factor for El Niño, produces a correspondence with recorded global temperatures which is well within the uncertainty range of the measurements. Some 70% of the wavelengths in this model have been detected in geological studies published by the Geological Society.

The Antarctic Ice cores show that the extreme minima of temperatures always lie between 9.5 and 10.5 degrees centigrade below present values, the maxima between 2 and 3 degrees above. It is implausible that the change from declining to increasing CO₂ levels would occur consistently at those low temperatures, unless the temperature change itself was induced externally. Indeed, abrupt changes in temperature gradient always precede similar changes in CO2 level; supporters of the AGW narrative claim some published work disproves this, but oddly, the results, on examination, show that either temperature change occurs first (50% of the examples), or are ambiguous (remaining 50%).

In conclusion, it is difficult to see how any thoughtful geologist can support the AGW hypothesis; I suggest that it is time that the Geological Society initiates a debate to review their “position” on AGW rather than jumping on a decarbonisation bandwagon, as proposed by Martin Lack.

Peter Owen (FGS)