September 11, 2013 დატოვე კომენტარი
The Intergovernmental Panel on Climate Change’s data on global temperatures, which coincides with that of the UK Met Office, clearly shows a 16 year pause in surface temperatures on Earth. While nobody will doubt that carbon dioxide is a greenhouse gas, and that it is theoretically possible for anthropogenic CO2 emissions to have some effect upon climate, it is now subject to debate as to how large an effect that is. The positive feedback loops between CO2 and temperature assumed by most researchers in the past need re-evaluating.
The suggestion that the sun has entered a “quiet” period is accepted by many scientists. Causal associations between “quiet” periods and cooler than normal temperatures, or ice ages, have long been suggested and evidence of this is accumulating. Likewise, very vigourous solar activity is associated with warmer than normal temperatures, and research investigating a possible causal link is coming up with very interesting results.
The paper below by Australian scientist David Archibald makes for compelling reading. Based on the premise that a significant cooling event may be realised in the near future, it objectively calculates the effects upon the world’s grain production, and hence upon prices and food security. Hopefully such an event will not occur, but if it should do so, good investments will be graingrowing land in regions with mild climates and long, warm growing seasons, as these will suffer less from yield impairment than regions that already have short growing seasons (like Canada and Russia). It would also be prudent to short-sell Egyptian stocks according to this analysis………although we must hope that it does not come to pass.
Guest essay by David Archibald
There is now consensus that the Sun has now entered a quiet period. The first paper from the solar physics community predicting the current quiet period was Schatten and Tobiska’s 2003 paper “Solar Activity Heading for a Maunder Minimum?”. To date, Solar Cycle 24 has shown similar maximum SSN amplitudes to that of Solar Cycle 5, the first half of the Dalton Minimum:
Figure 1: Solar Cycle 24 relative to the Dalton Minimum
But what comes beyond that? Predicting the amplitude of Solar Cycle 24 was big business in the solar physics community with a total of 75 forecasts. There is only one forecast of the amplitude of Solar Cycle 25 to date. That forecast is Livingstone and Penn’s prediction of a maximum amplitude of seven. The first forecast, by Libby and Pandolfi, of the current quiet period is now over 40 years old. The fact that Libby and Pandolfi’s prediction got the detail of temperature changes to date right gives great credibility to it. Written in 1979, they forecast a warming trend for the rest of the 20th century followed by a cold snap that might well last throughout the first half of the 21st century. Specifically, Dr Libby is quoted by the Los Angeles Times as saying,
“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 Libby and Pandolfi forecast was based on isotope ratios in tree rings and dates from a time before the corruption of tree ring science.
Read the rest of this fascinating article here