An extensively peer-reviewed study published last December in the Journal of Atmospheric and Solar-Terrestrial Physics indicates that observed climate changes since 1850 are linked to cyclical, predictable, naturally occurring events in Earth’s solar system with little or no help from us. The research was conducted by Nicola Scafetta, a scientist at Duke University and at the Active Cavity Radiometer Solar Irradiance Monitor Lab (ACRIM), which is associated with the NASA Jet Propulsion Laboratory in California. It takes issue with methodologies applied by the U.N.’s Intergovernmental Panel for Climate Change (IPCC) using “general circulation climate models” (GCMs) that, by ignoring these important influences, are found to fail to reproduce the observed decadal and multi-decadal climatic cycles.
As noted in the paper, the IPCC models also fail to incorporate climate modulating effects of solar changes such as cloud-forming influences of cosmic rays throughout periods of reduced sunspot activity. More clouds tend to make conditions cooler, while fewer often cause warming. At least 50-70% of observed 20th century warming might be associated with increased solar activity witnessed since the “Maunder Minimum” of the last 17th century.
Dr. Scafetta’s study applies an astronomically-based model that reconstructs and correlates known warming and cooling phases with decadal and multi-decadal cycles associated with influences of planetary motions, most particularly those of Jupiter and Saturn. This “astronomical harmonics model” was used to address various cycles lasting 9.1, 10-10.5, 20-21, and 60-62 year-long periods. The 9.1-year cycle was shown to be likely related to decadal solar/lunar tidal oscillations, while those of ten years and longer duration relate to planetary movements about the Sun that may have solar influences that modulate electromagnetic properties of Earth’s upper atmosphere which can regulate the cloud system.
Scafetta’s findings contradict IPCC claims that all warming observed from 1970 to 2000 has been man-made (“anthropogenically-induced”) based upon models that exclude natural quasi 20-year and 60-year climate cycle contributions. These cycles have been clearly detected in all global surface temperature records of both hemispheres since 1850, and are also evident in numerous astronomical records. The 60-year cycle is particularly easy to observe in significant surface temperature maxima that occurred in 1880-1881, 1940-1941, and 2000-2001. These momentarily warmer periods coincided with times when orbital positions of Jupiter and Saturn were relatively close to the Sun and Earth.
A 60-year modulation cycle also corresponds with warming/cooling induced in the ocean surface which appears to correlate with the frequency of major Atlantic hurricanes, and is seen in the sea level rise since 1700 as well as in numerous ocean and terrestrial records dating back centuries. Further evidence of a 60-year cycle is referenced in ancient Sanskrit texts among observed monsoon rainfall cycles. Scafetta believes that a natural 60-year climate cycle associated with astronomical cycles may also explain calendars adopted in traditional Chinese, Tamil and Tibetan civilizations, since all major ancient civilizations knew about 20-year and 60-year Jupiter and Saturn cycles. Indeed, Scafetta pointed out to me that in the Hindu tradition, the 60-year cycle is known as the cycle of Brihaspati, the name of Jupiter, and that every 60 years special ceremonies are celebrated by some populations, such as the Sigui ceremony among the Dogon people of Africa.
Proper reconstructions of natural 20-year and 60-year cycles, along with other independent studies, indicate that the IPCC has seriously overestimated human climate contributions. For example, according to all GCM simulations, increased CO2 concentrations should have produced an increased tropical warming trend with altitude, which is contrary to what balloon and satellites observations actually show.
GCM interpretations also allege that volcano activity may have contributed an offsetting 0.1-0.2 degrees of cooling influence between from 1970 to 2000. However, that conclusion appears to significantly overestimate the volcano signal because the models predicted deep and large cooling spikes associated with eruptions which are observed to be much smaller in global surface temperature records. Accordingly, this too suggests that the 1970-2000 warming effect attributed to anthropogenic influences should be reduced. Moreover, some of the observed 0.5 degrees of warming recorded by surface stations during the 1970-2000 period which IPCC models associated with human greenhouse gases emissions, may be explained by improperly corrected urban “heat island” effects and other land use change influences.
Finally, three major available global surface temperature record sources report a steady-to-cooling trend since 2001. These measurements contradict the strong warming predicted by all IPCC models during the same period that are attributed primarily to a continuing increase in CO2 emissions. Indeed, only one global surface record source shows a slight increase in the temperature since 2001. This occurred because missing temperature data needed to be adjusted or filled in to complete the records…which appears to be the case with NASA Goddard Institute for Space Studies model data resulting from poor sampling during the last decade for Antarctic and Arctic regions and the use of a 1200 km smoothing methodology.
The Duke University/NASA JPL study estimates that as much as 0.3 degrees of warming from 1970 to 2000 may have been naturally induced by the 60-year modulation during the warming phase, amounting to at least 43-60% of the 0.5-0.7 degrees allegedly caused by human greenhouse emissions. Additional natural warming can be explained by increased solar activity during the last four centuries, as well as simply being part of a natural and persistent warming recovery since the end of the Little Ice Age of AD 1300-1900.
Nicola Scaletta concludes that the scientific method requires that a physical model fulfill two conditions…it must be able to reconstruct as well as predict (or forecast) direct physical observations. Here, he argues that all climate models used by the IPCC can do neither. “They seriously fail to properly reconstruct even the large multi-decadal oscillations found in the global surface temperature which have climatic meaning. Consequently, the IPCC projections for the 21st century cannot be trusted.” In fact, he argues that “By not properly reconstructing the 20-year and 60-year natural cycles we found that the IPCC GCMs have seriously overestimated also the magnitude of the anthropogenic contribution to recent warming.”
Unlike the current IPCC models, the astronomical harmonics model can have real climate forecasting value. By combining current trend information with natural cycle patterns Scafetta believes that the global temperature “may not significantly increase during the next 30 years mostly because of the negative phase of the 60-year cycle.” He goes on to say: “If multi-secular natural cycles (which according to some authors have significantly contributed to the observed 1700-2010 warming and may contribute to an additional natural cooling by 2100) are ignored, the same projected anthropogenic emissions would imply a global warming by about 0.3-1.2 degrees C by 2100, contrary to the IPCC 1.0-3.6 degree C projected warming.”
Scafetta projects that the global climate may remain approximately steady until 2030-2040 (as was observed from the 1940s to the 1970s) because the 60-year cycle entered into its current cooling phase around 2000-2003. The climate may further cool if additional natural long and short-term cycles also enter into cooling phases. In fact the present warm period may well be at the top of a natural millennial cycle as previously occurred during Roman and Medieval times.
When I asked Nicola how confident he is about his prognosis, he responded: “Of course there is a need to wait and see, and as I say in the paper, additional cycles may be needed for a better forecast. After all, ocean tides are currently predicted with 30-40 astronomical harmonic constituents, while in the proposed model I used only four harmonics. However, in the paper I did show that once the proposed model was calibrated from 1850 to 1950, it has been able to reproduce the decadal and multi-decadal modulation of the temperature observed from 1950 to 2011, and vice versa. Since 2000 the model has well captured the steady-to- cooling trend shown in temperature data, while all IPCC GCMs have failed the prognosis by predicting steady warming.”
So, as the old expression goes…time will tell. And assuming that his model prediction will prove to be correct, let’s enjoy basking in warmth while it lasts.
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