Volume 12, Number 8: 25 February 2009
Shaviv (2008) begins a most intriguing paper by noting, as background material, that "climatic variations synchronized with solar variations do exist, whether over the solar cycle or over longer time-scales," citing numerous references in support of this fact, many more of which can be found under the general heading of Solar Effects in our Subject Index. However, it is difficult for certain people (such as climate alarmists) to accept the logical derivative of this fact, i.e., that solar variations are driving major climate changes, the prime problem being that measured or reconstructed variations in total solar irradiance seem far too small to be able to produce the observed climatic changes.
One potential way of resolving this dilemma would be to discover some amplification mechanism; but most attempts to identify one have been fraught with difficulty and met with much criticism. In this particular instance, however, Shaviv makes a good case for at least the existence of such an amplifier, and he points us in the direction of a sensible candidate to fill this role.
Shaviv's course of action was to "use the oceans as a calorimeter to measure the radiative forcing variations associated with the solar cycle" via "the study of three independent records: the net heat flux into the oceans over 5 decades, the sea-level change rate based on tide gauge records over the 20th century, and the sea-surface temperature variations," each of which can be used "to consistently derive the same oceanic heat flux."
In pursuing this path, Shaviv demonstrates "there are large variations in the oceanic heat content together with the 11-year solar cycle." In addition, he reports that the three independent data sets "consistently show that the oceans absorb and emit an order of magnitude more heat [our italics] than could be expected from just the variations in the total solar irradiance," thus "implying," as he describes it, "the necessary existence of an amplification mechanism, although without pointing to which one."
Finding it difficult to resist pointing, however, Shaviv acknowledges his affinity for the solar-wind modulated cosmic ray flux (CRF) hypothesis, which was suggested by Ney (1959), discussed by Dickenson (1975), and championed by Svensmark (1998). Based on "correlations between CRF variations and cloud cover, correlations between non-solar CRF variations and temperature over geological timescales, as well as experimental results showing that the formation of small condensation nuclei could be bottlenecked by the number density of atmospheric ions," this concept, according to Shaviv, "predicts the correct radiation imbalance observed in the cloud cover variations" that are needed to produce the magnitude of the net heat flux into the oceans associated with the 11-year solar cycle.
Shaviv thus concludes that the solar-wind modulated CRF hypothesis is "a favorable candidate" for primary instigator of all of the many climatic phenomena described in the Solar Effects section of our Subject Index. And we tend to agree with his characterization: not yet proven, but looking good.
Sherwood, Keith and Craig Idso
Dickinson, R.E. 1975. Solar variability and the lower atmosphere. Bulletin of the American Meteorological Society 56: 1240-1248.
Ney, E.P. 1959. Cosmic radiation and weather. Nature 183: 451.
Shaviv, N.J. 2008. Using the oceans as a calorimeter to quantify the solar radiative forcing. Journal of Geophysical Research 113: 10.1029/2007JA012989.
Svensmark, H. 1998. Influence of cosmic rays on earth's climate. Physical Review Letters 81: 5027-5030.