This amazing new potential finding - which has been established for only two of the putative 100,000-year cycles and, hence, could still turn out to be spurious - is the work of Mukul Sharma of the Department of Earth Sciences at Dartmouth College.  It is based upon the fact that the production of ¹⁰Be in earth's atmosphere is affected by the intensity of magnetic activity at the surface of the sun, as well as the earth's geomagnetic dipole strength.  Using preexistent data pertaining to these factors that were obtained from several different sources, Sharma (2002) began his analysis by compiling 200,000-year histories of relative geomagnetic field intensity (from natural remanent magnetizations of marine sediments) and normalized atmospheric ¹⁰Be production rate (also from marine sediments).  Then, with the help of a theoretical construct describing the ¹⁰Be production rate as a function of the solar modulation of galactic cosmic rays (which modulation arises from variations in magnetic activity at the surface of the sun) and earth's geomagnetic field intensity, he created a 200,000-year history of the solar modulation factor.

This history reveals the existence of significant periods of both enhanced and reduced solar activity; and comparing it with the marine ð¹⁸O record (a proxy for global ice volume and, hence, earth's mean surface air temperature), it was found that the two histories are strongly correlated.  As Sharma describes it, "the solar activity has a 100,000-year cycle in phase with the ð¹⁸O record of glacial-interglacial cycles," such that "the long-term solar activity and earth's surface temperature appear to be directly related."  Throughout the entire 200,000-year period, for example, Sharma notes that "the earth has experienced a warmer climate whenever the sun has been magnetically more active," and that "at the height of the last glacial maximum the solar activity was suppressed."  Hence, it was easy for Sharma to make the final, obvious connection; and as he did so, he set forth as a new hypothesis the proposal that "variations in solar activity control the 100,000-year glacial-interglacial cycles," just as they also appear to control essentially all other imbedded and cascading climatic cycles.

With the subsequent publication of Sharma's impressive analysis, there is now more reason than ever to look to the sun as the cause of the global warming of the past two centuries (Esper et al, 2002), for the sun has now been implicated as the causative agent of just about every scale of climatic change imaginable.  And if the sun could free the planet from the frigid grip of a full-fledged ice age, it should have been a simple thing indeed for it to have ushered us out of the much more moderate Little Ice Age and into the Modern Warm Period in which we currently live, as something clearly did over the course of the past two centuries.

With respect to the future, we note that the current value of the solar modulation factor is considerably lower than it was during the two preceding interglacials, which suggests that it may rise even higher and thereby significantly extend the warming the planet has experienced to this point in time.  Such is also suggested by the fact that the peak warmth of the current interglacial or Holocene is more than 2°C cooler than the peak warmth of the four preceding interglacials (Petit et al., 1999), plus the fact that the planet is currently significantly cooler than it was during the peak warmth of the mid-Holocene, and that it is possibly even cooler now than it was during the more recent Medieval Warm Period.  Consequently, as is readily evident, there is a multitude of reasons - none of them related to the ongoing rise in the air's CO2 content, however - for expecting the earth to continue to warm even more in the coming years and decades; and it would thus behoove the nations of the earth to utilize their resources in preparing for that eventuality, rather than wasting their wealth in an ill-advised battle against an illusionary adversary (anthropogenic CO2 emissions) that could well prove a godsend in helping earth's vegetation cope with a warming climate, as described in many places on our website and as articulated in Science by Cowling (1999), who wisely says we should be less concerned about "rising temperatures and more worried about the possibility that future atmospheric CO2 will suddenly stop increasing, while global temperatures continue rising."

These observations clearly go to the very heart of the debate that rages over the struggle to accept or reject the Kyoto Protocol and anything like it; for if the sun truly rules in the heavens above, determining the nature and extent of essentially all climate change on the face of the earth, there is not a thing that man can do to change that fact.  If we are wise, therefore, and if what is outlined here is truly the case, we will do what the President of the United States, George W. Bush, long advocated before his recent equivocation.  We will strive for economic progress for all nations and plan for adapting to further warming, which surely would seem to be headed our way.

Reference
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Cowling, S.A.  1999.  Plants and temperature - CO2 uncoupling.  Science 285: 1500-1501.

Esper, J., Cook, E.R. and Schweingruber, F.H.  2002.  Low-frequency signals in long tree-ring chronologies for reconstructing past temperature variability.  Science 295: 2250-2253.

Friis-Christensen, E. and Lassen, K.  1991.  Length of the Solar-cycle - an indicator of Solar-activity closely associated with climate.  Science 254: 698-700.

Petit, J.R., Jouzel, J., Raynaud, D., Barkov, N.I., Barnola, J.-M., Basile, I., Bender, M., Chappellaz, J., Davis, M., Delaygue, G., Delmotte, M., Kotlyakov, V.M., Legrand, M., Lipenkov, V.Y., Lorius, C., Pepin, L., Ritz, C., Saltzman, E., and Stievenard, M.  1999.  Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica.  Nature 399: 429-436.

Sharma, M.  2002.  Variations in solar magnetic activity during the last 200,000 years: is there a Sun-climate connection?  Earth and Planetary Science Letters 199: 459-472.

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