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Testing greenhouse

By Mark S. Lawson - posted Friday, 23 January 2009


Then what about the mid-range or low end of the forecasts? Given they way they were originally constructed the mid and low range projections are much harder to confirm, or dismiss, but recent developments will make the next few years worth of temperature trends most interesting to follow.

If the results flatline over the next few years, the climate modellers are still looking good. As I have noted in previous posts, there has been some work in modifying greenhouse theory by adding in climate cycles, including the likes of La Niña, El Niño and the Atlantic Meridional Overturning (AMO) circulation. There are a whole zoo of climate cycles which scientists are only just beginning to understand, and which certainly have a major influence on global temperatures.

After studying the AMO, one group led by Noel Keenlyside of the Leibnitz Institute of Marine Sciences, has declared that temperatures will remains static and even weaken up to 2015 before turning up (Letters Nature, May 1 2008). In April of this year, NASA also announced that, despite La Niña fading away, the important Pacific Decadal Oscillation had shifted from its warm mode to cool mode. One scientist who tracks the PDO, Don J. Easterbrook at the Department of Geology, Western Washington University, has since stated publically - albeit not in the refereed literature - that the PDO shift “virtually assures” global cooling for the next 25-30 years.

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If the PDO, and AMO, are that important then one would think we should see some cooling in the next few years. Although the climate record obviously has a lot of noise in it, overall the trend should be down. Let’s see what temperatures do. Let’s test these various propositions.

Then there are those who point to solar activity as the over-riding factor in climate, with the sun now obligingly arranging a test for their theories. As previously noted the sun has well-recognised 11-year cycle marked by numbers of sun spots. Those spots have been absent for almost a year since the last cycle ended, and no one knows when the next cycle will start. There are various forecasts, all based on statistical analysis rather than any theory (what scientists thought they knew about the internal workings of the sun has been proved wrong), that the next cycle will start sometime later this year or remain quiet until past 2014. Take your pick. As the former forecasts surfaced only after the sun had gone quiet I would go with the latter, but whatever. We will find out.

If the sun continues to be quiet the results could be interesting. There is evidence linking solar minimums with cold periods in earth’s history, as well as published scientific papers linking solar activity of various sorts, including changes in solar magnetic fields (which influences that of the earth) with climate. One such recent paper in the journal Geology, January 2009, is titled Is there a link between Earth’s magnetic field and low-level precipitation?

None of this adds up to an integrated, accepted theory on climate, or even a part of one, particularly as there is a lot of debate over the exact mechanism linking the sun and the earth’s climate. Again the orthodoxy has pushed aside all doubts, and all greenhouse proponents have to do is point to that. “It’s carbon, and all those laymen who doubt the climate models should go and soak their heads.”

However, scientists can be over-ruled by nature and as we have seen there are various reasons for believing that temperatures will fall and, one would think, fall noticeably over the next couple of years. If they flat line or increase noticeably then the climate modellers can line up for their humanitarian awards.

Can we wait several years before doing anything? Most definitely. In fact, as noted in other posts efforts to curtail industrial emissions globally are a waste of time and money. It is simply not going to happen. Instead of cutting emissions now, Governments can wait a little then invested in adaptation measures and on (hopefully) cheaper technology to clean up emissions when it becomes available. Greenhouse proponents will consider this to be highly unsatisfactory, but even if the science is right waiting will make no difference to the final result.

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This article is adapted from one published in the Summer 2008-2009 issue of The Skeptic, produced by the Australian Skeptics.



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About the Author

Mark Lawson is a senior journalist at the Australian Financial Review. He has written The Zen of Being Grumpy (Connor Court).

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