The annual atmospheric CO2 variation: A new theory – Net Zero Watch

Arctic sea ice [image credit: Geoscience Daily]

The authors propose that sea-ice formation is the key factor and not biology. In their paper, we read: ‘Results: Carbon dioxide is very strongly correlated with sea ice dynamics, with the carbon dioxide rate at Mauna Loa lagging sea ice extent rate by 7 months.’ However, drawing conclusions from correlations can go wrong. The authors conclude: ‘If sea ice does not drive the net flux of these gases, it is a highly precise proxy for whatever does. Potential mechanisms should be investigated urgently.’
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Could we be wrong about the annual cycle of carbon dioxide in the atmosphere? – asks Net Zero Watch.

That’s the suggestion by a pair of distinguished Oxford zoologists Clive Hambler and Peter Henderson who have just published a paper that could change our understanding about one of the key observations of this greenhouse gas.

They propose that sea-ice formation is the key factor and not biology.

The amount of carbon dioxide in the atmosphere has risen since records were kept regularly, about 1960. Superimposed on the trend is a seasonal cycle which, when measured at the Mauna Loa Observatory in Hawaii, is very regular usually peaking in May. Some scientists have called this cycle “the Earth breathing,” as they attribute it to biological activity on the large land masses of the Northern Hemisphere.

There is also a methane cycle though it is more complex and less regular, with peaks around November.

The Oxford researchers, however, point out that the “earth-breathing” explanation for the annual carbon dioxide cycle is not as secure as many think.

The global carbon dioxide net emission rate has a correlation of only 0.77 (significant at the 99.99% level) with lower tropospheric temperatures for the tropical land region. Also, despite considerable effort to find the location, there is great uncertainty about where​​ the “earth breathing” is taking place.

In addition, terrestrial biological productivity in the Northern Hemisphere is typically measured by a factor called NDVI (sometimes called “greenness”) but the researchers point out that this is less strongly correlated with carbon dioxide rates than are sea ice rates.

“To our knowledge no region has been shown to have extremely high temporal synchrony and hence statistical correlation with the global carbon dioxide rate.”

Full article here.
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Paper: Clive Hambler, Peter Alan Henderson, Temperature, Carbon Dioxide and Methane May Be Linked Through Sea Ice Dynamics, International Journal of Atmospheric and Oceanic Sciences. Volume 6, Issue 1, June 2022 , pp. 13-34. doi: 10.11648/j.ijaos.20220601.13

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August 20, 2022 at 03:10AM

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