This assumption does not consider long-term changes in natural source and sink rates.
The long-term proxied ice core data for atmospheric CO2 concentrations indicate that these natural changes are significant and should be considered in any mass balance type of calculation.
by Fred Haynie I conclude that, the IPCC’s model assumptions that long-term natural net rate of accumulation is constant and anthropogenic emission rates are the only contributor to total long-term accumulation of atmospheric CO2, is false.
All the data I have analyzed are evidence that reported monthly averages are measurements of a global distribution of background levels of CO2.
The average of all the two standard deviations is only 2.2 ppm.
Any locational differences appear to be insignificant.
The seasonal variation is likely the results of the ever-changing unfrozen sink area (both ocean and land biosphere).
Anthropogenic emissions are not temperature dependent. Therefore, evidence for an anthropogenic increase in atmospheric CO2, is more likely to be observed in long term changes with the seasonal variations factored out.A similar analysis of 13CO2 index data yields the following plot. Change in 13CO2 index in the Arctic as a function of time.https://curryja.files.wordpress.com/2010/09/cropped-header21" data-medium-file="https://curryja.files.wordpress.com/2010/09/cropped-header21.jpg? w=300" data-large-file="https://curryja.files.wordpress.com/2010/09/cropped-header21.jpg? w=500" class="aligncenter size-full wp-image-95" src="https://retiredresearcher.files.wordpress.com/2011/11/13co2.jpg? This plot is based on eight sets of flask data from the same region north of 60N.Event flask measurements that were exceptionally high (that could be from local anthropogenic sources) have been flagged and were not included in monthly averages.The result is a consistent global uniformity with no significant variation with longitude and a latitude dependent seasonal variation.