Three Papers of Interest – Long-term Cycles

A scientist – Michael Asten, professor of geophysics at Monash University – responds to Obama’s global warming rhetoric:

It was an appeal using rhetoric and not science because the most severe impacts of these natural disasters come from the challenge of managing increased population or changed population demands, not changes in the events per se…

I note three recent papers that find evidence for long-term cycles influencing the Earth’s climate.

Weichao Wu of the Peking University and colleagues studied sea-surface temperature records preserved in deep-sea sediments near Okinawa in the Pacific Ocean, and found evidence for multiple cyclic temperature variations over the past 2700 years.

The most interesting temperature peaks correspond to medieval, Roman and possibly Minoan warming periods of about 900, 1800 and 2500 years ago.

The paper is significant in that it concludes that the current rate of global temperature change lies in the same range as that of those historical warming periods.

This suggests we have evidence that challenges current climate orthodoxy on two grounds, first by suggesting that such warming events were global not local European phenomena, and second that current warming is not unprecedented in the historical record.

While we read many claims by oceanographers of an increasing rate of rise in sea-levels associated with increased atmospheric carbon dioxide, an alternative interpretation of observed data is made in a recent analysis by Don Chambers of the University of South Florida and colleagues.

Chambers poses the question: “Is there a 60-year oscillation in sea-level?” and shows evidence that the answer is probably yes.

I read his data and find it is arguable that the upswing of that oscillation is responsible for about half of the current 3mm/year rate of rise, leaving the background rate of rise at about 1.7mm, where it has been for 110 years…

I would add that if Chambers is right, the accelerating rate of increase in sea-levels has topped out about now, and the 10mm a year rises needed to reach the feared “1 metre rise by 2100” are not going to happen.

A third work … is a study by JA Abreu of the prestigious Swiss university ETH, with co-authors including Australia’s 1995 Australia Science Prize winner Ken McCracken.

Abreu reconstructs a history of solar sunspot cycles over the past 10,000 years… These records show a series of cycles ranging from 88 years to 504 years with longer cycles of 974 and 2300 years evident …


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