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Solar Link to 50% of Warming During the Past 100 Years? December 13, 2008

Posted by honestclimate in sunspots.
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Solar Link to 50% of Warming During the Past 100 Years?

By Paul Biggs, Climate Research News

There is a new paper ‘in press’ in Geophysical Research Letters by Eichler et al entitled, ‘Temperature response in the Altai region lags solar forcing’.The Abstract states:

The role of the sun on Earth’s climate variability is still much debated. Here we present an ice core oxygen isotope record from the continental Siberian Altai, serving as a high-resolution temperature proxy for the last 750 years. The strong correlation between reconstructed temperature and solar activity suggests solar forcing as a main driver for temperature variations during the period 1250-1850 in this region. The precisely dated record allowed for the identification of a 10-30 year lag between solar forcing and temperature response, underlining the importance of indirect sun-climate mechanisms involving ocean induced changes in atmospheric circulation. Solar contribution to temperature change became less important during industrial period 1850-2000 in the Altai region.

In the Results and Discussion the authors write: “Our reconstructed temperatures are significantly correlated with the 10Be and 14C based solar activity reconstructions in the period 1250-1850, but not with the greenhouse gas CO2. This indicates that solar activity changes are a main driver for the temperature variation in the Altai region during the pre industrial time. However, during the industrial period (1850-2000) solar forcing became less important and only the CO2 concentrations show a significant correlation with the temperature record. Our results are in agreement with studies based on NH temperature reconstructions [Scafetta et al., 2007] revealing that only up to approximately 50% of the observed global warming in the last 100 years can be explained by the Sun.”

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Whilst this paper supports studies by Scafetta et al, it is clear that solar factors are still poorly understood, and there are many factors other than CO2 or Solar involved in climate change. A correlation with post industrial CO2 does not necessarily imply causation. For example, Tsonis et al, 2007 investigated the collective behavior of known climate cycles such as the Pacific Decadal Oscillation, the North Atlantic Oscillation, the El Nino/Southern Oscillation, and the North Pacific Oscillation.

By studying the last 100 years of these cycles’ patterns, they found that the systems synchronized several times. In cases where the synchronous state was followed by an increase in the coupling strength among the cycles, the synchronous state was destroyed. Then, a new climate state emerged, associated with global temperature changes and El Nino/Southern Oscillation variability. The suggestion is that this mechanism explains all global temperature tendency changes and El Nino variability in the 20th century.

See post here.

Comments»

1. Dan Pangburn - December 13, 2008

During the last and previous glacial periods there were temperature and carbon dioxide up-trends and downtrends. Credible data from Vostok and EPICA showing these trends are readily available. Close examination of these data shows unequivocally that on many occasions temperature trended down for centuries while carbon dioxide level was higher than it had been during a prior temperature uptrend. This shows that, at least at that time, temperature was not driven by carbon dioxide level.

It is well known that added increments of carbon dioxide have less influence than previous increments. This has been elucidated using the added-blankets metaphor. Since there is more carbon dioxide in the atmosphere today than during the glacial periods, added increments of carbon dioxide today have even less influence than they did during the glacial periods when they did not drive temperature. Thus added atmospheric carbon dioxide today does not drive temperature and AGW that is based on increased atmospheric carbon dioxide is a mistake.


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