Guest post by David Archibald
When I started out in climate science in 2005, the climate people ignored the solar physics community. A casual perusal of the literature though indicated that the difference in climate outcome from Dikpati’s (NASA) estimate for Solar Cycle 24 amplitude of 190 and Clilverd’s (British Antarctic Survey) estimate of 42 amounted to 2.0°C for the mid-latitudes.
Since then, the prognostications of astute scientists with respect to Solar Cycle 24 amplitude have come to pass. Some commentators though are over-reaching and predicting a recurrence of the Maunder Minimum. We now have the tools to predict climate out to the mid-21st Century with a fair degree of confidence, and a repeat of the Maunder Minimum is unlikely. A de Vries Cycle repeat of the Dalton Minimum is what is in prospect up to the early 2030s and then a return to normal conditions of solar activity, and normal climate.
The three tools we have to predict climate on a multi-decadal basis are the solar cycle length – temperature relationship, the logarithmic heating effect of carbon dioxide and Ed Fix’s solar cycle prediction. Let’s start with the solar cycle length – temperature relationship, first proposed by Friis-Christensen and Lassen in 1991. This is the relationship for Hanover, New Hampshire:
The relationship established for Hanover is a 0.7°C change in temperature for each year of solar cycle length. Solar Cycle 23 was three years longer than Solar Cycle 22, and thus the average annual temperature for Hanover, New Hampshire will be 2.1°C lower over Solar Cycle 24 than it had been over Solar Cycle 23. Why did I pick Hanover? Governor Lynch recently vetoed New Hampshire leaving the Regional Greenhouse Gas Initiative.
Professor Jan-Erik Solheim of Oslo University replicated this methodology for ten Norwegian temperature records, and thus this methodology is confirmed as valid:
These ten Norwegian temperature records all confirm a solar cycle length – temperature relationship, and predict that temperatures of these stations will be about 1.5°C colder over the next ten years than they have been over the last ten years.
The second tool to use is the logarithmic heating effect of carbon dioxide. The pre-industrial level of carbon dioxide in the atmosphere was approximately 290 ppm. It is currently 390 ppm. The first 20 ppm of carbon dioxide in the atmosphere provides half the heating effect to date. By the time we get to the current concentration, each additional 100 ppm provides a further 0.1°C of heating. We are currently adding 2 ppm to the atmosphere each year so carbon dioxide will provide further heating of 0.1°C every 50 years. That said, the temperature fall over the next 22 years should result in a higher rate of carbon dioxide uptake by the oceans. The logarithmic heating effect of carbon dioxide is shown by this graph, using data derived from the Modtran site at the University of Chicago:
Lastly, to put a multi-decadal climate forecast together, we need a prediction of solar cycle length that comes with a very good hindcast match. This is provided by Ed Fix’s long ephemeris simulation. This simulation is described in Ed Fix’s paper which is included in an Elsevier volume edited by Don Easterbrook, “Evidence-Based Climate Science”, due out in September. You can put advance orders in for it now:
This is a window of Ed Fix’s simulation:
The green line is the solar cycle record from 1914 to 2010, with alternate cycles reversed. Solar Cycles 19 to 23 are annotated. The red lines is the model output, from which the lengths of individual solar cycles in the mid-21st Century can be calculated.
Combining all the above tools, this is the climate forecast for Hanover, New Hampshire, which is a good proxy for what is going to happen along the US-Canadian border:
Solar Cycles 24 to 27 are annotated. For the next thirty years odd, temperatures will be at mid-19th Century levels. With the two year decrease in the length of Solar Cycle 26 from 25, temperatures will rise by 1.4°C by mid-century to late 20th Century levels.
By then, anthropogenic carbon dioxide will be providing a very welcome 0.2°C to the temperature.
The graph shows that quantified solar effects dwarf the quantified anthropogenic carbon dioxide effect.
12th July 2011