Pay Pal Donation
Index of Editorials
Climate Science Climate Cycles


All Editorials for
2013
2012
2011
2010
2009
2008

Categories
Subcategories

Antarctic Warming
Skepticism [2]

Book
Review [2]

Climate Change
CO2 Emissions [1]

Climate Models
Uncertainty [2]

Climate Science
Climate Cycles [1]
Climate Sensitivity [1]
Holes [1]
Thermal History [1]
Unsolved Problems [1]

Energy Issues
American Power Act [1]
Clean and Sustainable [1]
Nuclear Waste Storage [1]
Renewable Electricity Standard (RES) [1]

Environmentalism
Surrogate Religion [1]

Foreword
Energy Primer for Kids [1]

Geo-Engineering
Applications [2]

Global Climate - International
French Academy [1]

Global Warming
Anthropogenic Global Warming (AGW) [6]
Confusion [1]
Economics [1]
General [2]
Greenhouse Gases [1]
Hockeystick [4]
Ice Cores [1]
Junkscience [9]
Oceans' Role [2]
Skepticism [1]
Sun's Role [2]

Health Issues
Second Hand Smoke [1]

Measurements
Arctic Sea Ice [1]
Atmospheric Temperature Data [2]
Sea Surface Temperature [1]
Surface Data [2]

Misinformation
Statistics Misuse [1]

Modern Empirical Science
v. Medieval Science [1]

NIPCC
China [1]

Nuclear Fuel
Supplies [1]

Organizations
Climate Research Unit (CRU) [1]
International Panel on Climate Change (IPCC) [2]
Nongovernmental International Panel on Climate Change (NIPCC) [1]
UK Met Office [1]
World Meteorological Organization (WMO) [1]

Political Issues
Climate Realism [1]
Climategate [3]
Independent Cross Check of Temperature Data [1]

Report
IPCC Assessment Report [2]
NOAA State of the Climate 2009 [1]
NRC-NAS Advancing the Science of Climate Change [1]

Sea-Level Rise
West Antarctic Ice Sheet (WAIS) [1]
Alarmism [1]

Types of Energy
Nuclear Energy [1]
  • 04-Apr-09 On Causes and Mechanisms of the 1500-Year Climate Cycles
  • SEPP Science Editorial #11-2009
    (in TWTW Apr 4, 2009)

    S. Fred Singer, Chairman and President , Science and Environmental Policy Project (SEPP)

    On Causes and Mechanisms of the 1500-Year Climate Cycles

    Apr 4, 2009

    The existence of a (roughly) 1500-year climate cycle of abrupt warming and cooling, first noted in Greenland ice cores by Dansgaard and Oeschger, is well established from a multitude of geological data [Singer and Avery. Unstoppable Global Warming: Every 1500 Years. Rowman & Littlefield Publ. 2007]. The cycle appears to extend into the Holocene and can account for the Medieval Warm Period (MWP) and Little Ice Age (LIA) [Loehle and Singer 2009]. Its synchronicity seems to be preserved. Early on, Bond [2001] suggested a solar cause; but we do not know of any solar phenomenon with such a period. Nor do we know the mechanism by which the Sun could cause such abrupt climate changes.

    In view of the fairly precise timing of the cycle, we speculate that purely internal oscillations of the oceanatmosphere system are unlikely to be the principal or only cause. We also note that the amplitude of D-O events was much larger during the period of glaciation than during the current warm period of the Holocene. We therefore favor a quasi-periodic internal oscillation synchronized by a solar trigger; the mechanism resembles "stochastic resonance." This would also account for the occurrence of missing cycles. As to the actual mechanism, we favor changes in solar activity modulating the energy spectrum of Galactic Cosmic Rays [Singer 1958] and thereby the flux of GCR impinging on the Earth's atmosphere. The most reasonable way this could affect the climate is by changes in cloudiness [Svensmark 2007]. The large amplitude of the D-O events suggests a positive feedback, perhaps a greenhouse effect, ultimately limited by a negative feedback inherent in the atmosphere-ocean system. Although many puzzles still remain, the observations suggest that large-amplitude abrupt changes become less likely in a warmer climate [NRC 2002].

    Why is that?

    (1) One reason might be that a colder ocean mixed-layer contains more dissolved CO2 and therefore releases more CO2 into the atmosphere when warmed - compared to a warmer Holocene ocean.

    (2) Further, this released CO2 produces a stronger GH forcing when added to the low CO2 levels of the ice ages -- because of the well-accepted logarithmic dependence of CO2 forcing on CO2 concentration.

    (3) Even more important, the ice-age atmosphere is extremely dry; there is little evaporation from the cold ocean surface and ice cover. Hence there will be little or no 'negative feedback' from WV or from clouds. (I am assuming here that such a feedback exists now -- reducing the GH effects of CO2). So one can see the full GH effect of CO2.

    (4) Finally, we don't see "run-away warming" because the amount of CO2 released from the mixed layer is limited. (At much higher temperatures, of course, the 'thermostat' effect of Ramanathan would operate.)

    View The Week That Was in which this editorial appeared.

    Return to Top of Page


    Free use is granted for non-commercial purposes of all materials on this Website.
    Acknowledgement would be appreciated.
    SEPP is funded through the generous contributions of individuals such as yourself. Pay Pal Donation
    (c) Copyright 2010-2018 Science and Environmental Policy Project