Guest post by David Archibald
A large part of the US is currently in drought. A recent paper by Springer et al – “Solar forcing of Holocene droughts in a stalagmite record from West Virginia in east central North America” – analysed the Sr/Ca ratios and C13 values in a Holocene stalagmite from east-central North America. Their work “demonstrates solar forcing of droughts in east-central North America on multiple time scales. Droughts typically occur during solar minima when SST in the Atlantic and Pacific Oceans are comparatively cool. These SST anomalies cause migration of the jet stream away from east-central NA, yielding decreased meridional moisture transport and reduced convergence over east-central NA.”
Futhermore: “The 210-year period coherency in the BCC-002 Sr/Ca andd13C time series is evidence that the de Vries solar irradiance cycle has significant effects upon moisture levels in east-central NA.”
So, to predict the onset of de Vries cycle droughts in North America, all we have to know is when the last de Vries cycle started. That was in 1798 at the beginning of the Dalton Minimum. 210 years after 1798 makes 2008, which happens to be the end of Solar Cycle 23 and the beginning of Solar Cycle 24. Solar activity has been quite weak since 2008, so everything is happening on schedule.
That is shown in the following figure of the annual average temperature of Providence, Rhode Island:
The periods of the Dalton Minimum (Solar Cycles 5 and 6) and the current Eddy Minimum (Solar Cycles 23 and 24) are shown as blocks. Gleissberg maxima and minima from a paper by Peristykh and Damon are shown as down-facing red arrows and up-facing blue arrows respectively. The next Gleissberg maximum should be around 2043, which agrees with a projection of solar activity by Fix (2011, in press).
Separate to the de Vries cycle-based projection of climate, the onset of a cold period is confirmed by application of Friis-Christensen and Lassen theory, shown above on the temperature record of Providence, Rhode Island.
Drought has an obvious agricultural impact, but this will be compounded by lower average temperatures and a shorter growing season.
Edmund Burke (1729-1797) stated that “Those who don’t know history are destined to repeat it.” Whether or not we are aware of previous de Vries cycle events, we are going to experience them and their consequences anyway, but knowing means that should not be a surprise.
Links to papers cited: