Monday, 21 May 2012

Premonitions of the Fall (in temperature)

 

Posted on May 20, 2012by Anthony Watts

Guest post by David Archibald

The first prediction of the current climatic minimum was made by Hubbert Lamb in 1970 in a report (Weiss and Lamb) for the German Navy. He did it by making a reconstructed record of the average frequency of south-westerly surface winds in England since 1340. Quoting Lamb “We sense a cycle or periodicity of close to 200 years in length.” and “There may be a valuable indication of the origin of this apparent 200 year recurrence tendency, in that the sharp declines of the south-westerly wind indicated in the late 1300s, 1560s, 1740s-1770s and now, in each case fell at about the end of a sequence of sunspot cycles which built up to periods of exceptionally great solar disturbance (around 1360-80, the 1570s, the 1770s, the 1950s and more recently). The frequency maxima of the south-westerly wind, and evidence of warm climate periods in Europe sustained over several decades, all bear a similar relationship to these variations of the Sun’s activity.”

Following is Figure 11.6 from Lamb’s 1988 book “Weather, Climate and Human Affairs”:

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The frequency of the southwest wind at London is shown by the solid line. A tentative forecast (broken line) is made simply by moving the whole curve 200 years to the right, i.e. the forecast implied by accepting the apparent 200 year recurring oscillation shown by the series.

The most successful prediction of the current minimum, in terms of lead time and detail, was made by two researchers in the US later that decade. Using tree ring data from redwoods in Kings Canyon in California, in 1979 Libby and Pandolfi forecast that, “by running this function into the future we have made a prediction of the climate to be expected in King’s Canyon; the prediction is that the climate will continue to deteriorate on the average, but that after our present cooling-off of more than the average decay in climate, there will be a temporary warming up followed by a greater rate of cooling-off.”

In a Los Angeles Times interview, Libby and Pandolfi gave a more detailed forecast:

“The forecast is for continued cool weather all over the Earth through the mid-1980s, with a global warming trend setting in thereafter for the rest of the century – followed by a severe cold snap that might well last through the first half of the 21st century.”

“Both the isotope record and the thermometer record show neat agreement for the cold decades at the ends of the 17th and 18th centuries, when temperatures fell by 1-10th to 2-10ths of a degree.”

“More recently, the world has enjoyed an agricultural boom during the past 70 years or so. The Earth’s annual average temperature has risen by about 1 to 1½ degrees, about as much of an increase as the decrease during the Little Ice Ages, during this interval.

When she and Pandolfi project their curves into the future, they show lower average temperatures from now thorugh the mid-1980s. “Then,” Dr. Libby added, “we see a warming trend (by about a quarter of 1 degree Fahrenheit) globally to around the year 2000. And then it will get really cold – if we believe our projections. This has to be tested.”

How cold? “Easily one or two degrees,” she replied, “and maybe even three or four degrees.”

The remarkable thing about the Libby and Pandolfi prediction is that they got the fine detail right, up to the current day, which gives a lot of credence to their projection for the next fifty years.

In 2003, two solar physicists, Schatten and Tobiska, published a paper which included the following prediction: “The surprising result of these long-range predictions is a rapid decline in solar activity, starting with cycle #24. If this trend continues, we may see the Sun heading towards a “Maunder” type of solar activity minimum – an extensive period of reduced levels of solar activity.”

The next prediction of the current minimum was made by Clilverd et al in 2006 using low-frequency solar oscillations:

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Clilverd predicted that Solar Cycles 24 and 25 would have amplitudes similar to that of Solar Cycles 5 and 6 of the Dalton Minimum before a return to more normal levels mid-century.

A Finnish tree ring study (http://lustiag.pp.fi/holocene_trends1000_INQUA.pdf) followed in 2007 – Timonen et al. This is a portion of a figure from that study showing a forecast cold period starting about 2015 that is deeper and broader than any cold period in the previous 500 years:

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Summary

Libby and Pandolfi provided timely warning of the current cooling more than thirty years ago, through the proper use of tree ring data. Given the enormous societal and financial consequences of that cooling, it would be good application of climate research funds to have a number of groups replicate and update the Libby and Pandolfi work.

References

Clilverd. M.A., Clarke, E., Ulich, T., Rishbeth, H. and Jarvis, M.J., 2006 “predicting Solar Cycle 24 and beyond” Space Weather, Vol. 4, So9005, doi:10.1029/2005SW000207

Libby, L.M. and Pandolfi, L.J. 1979, Tree Thermometers and Commodities: Historic Climate Indicators, Environment International Vol 2, pp 317-333

Schatten, K.H. and W.K.Tobiska 2003, Solar Activity Heading for a Maunder Minimum?, Bulletin of the American Astronomical Society, 35 (3), 6.03

Timonen, M., Helema, S., Holopainen, J., Ogurtsov, M., Eronen, M., Lindholm, M., Merilainen, J and Mielikainen, K. 2007 “Climate patterns in Northern Fennoscandinavia during the Last Millenium” Xvii INQUA Congress

Weiss, I. and Lamb, H.H. 1970 ‘Die Zunahme der Wellenhohen in jungster Ziet in den Operationsgebieten der Bundesmarine, ihre vermutliche Ursachen and ihre voraussichtliche weitere Entwicklung, Fachlich Mitteilungen, Nr. 160, Porz-Wahn, Geophysikalisher Bertungsdiesnt der Bundeswehr.

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