Unreliable information about CO2 emissions

Greenhouse gas emissions of the 1990s underestimated

11/02/2013

Information on CO2 emissions, which has often fixed CO2 reduction targets, is unreliable, according to an international research team from Australia, the US and Germany. Recent analyzes indicate that here is one „cumulative underestimation“ The researchers report to Roger Francey from the Center for Australian Weather and Climate Research „Nature Climate Change“. Often, carbon dioxide emissions from countries are not consistent with actual atmospheric values, write Francey and colleagues

According to the researchers, the values ​​determined on the basis of the government's CO2 emission figures were extremely unreliable, especially in the 1990s. The CO2 balance is calculated from the reported emissions minus the changes in the CO2 concentration in the air. The difference shows how much carbon dioxide is stored in the so-called CO2 sinks such as forests or oceans. Ideally, humans should not emit more CO2 than can be deposited in the CO2 sinks. The scientists around Roger Francey have now analyzed the evolution of carbon dioxide concentrations in the atmosphere since the 1990s, based on the data from two stations - one in Mauna Loa, Hawaii, and one in Cape Grim, Tasmania. The expected deviations between the northern and southern hemisphere have been confirmed in the measured data of the two stations. In the northern hemisphere, with its high density of industrialized and emerging economies, there was a stronger increase in carbon dioxide concentration than in the southern hemisphere.

CO2 emissions underestimated cumulatively
The growth of CO2 concentration demonstrated by the researchers and the „Inter-hemispheric concentration differences during the global financial crisis support the earlier speculation that the increase in reported emissions from 2000 to 2008 was due to a cumulative underestimation“ CO2 emissions in the 1990s can be explained, the scientists report. „What was observed during the zero years in the atmosphere did not fit the emission statistics“, said co-author Martin Heimann, head of the participating Max Planck Institute for Biogeochemistry in Jena. The analysis of global anthropogenic CO2 emissions with improved measurement and calculation methods has shown that the carbon dioxide emissions reported by the states appear to be a greater uncertainty factor than previously assumed.

Atmospheric measurement methods instead of government emission data
The deviations between the reported CO2 emissions and the development of the CO2 concentration in the air could theoretically also be caused by changes in the storage capacity of the CO2 sinks, but Francey and colleagues consider this scenario to be rather unlikely. Here it is rather to assume that the reported emission data from the 1900s did not correspond to the actual CO2 emissions. This finding seems quite problematic, as the national and international climate protection targets frequently proclaim a reduction in CO2 emissions compared to basic data from the 1990s. The findings of the researchers also raise general doubts about the accuracy of previous information on CO2 emissions. Here Francey and colleagues advocate the use of atmospheric measuring methods to avoid corresponding inaccuracies. With a network of measuring stations, the emission rate could be much better controlled in the future, the researchers concluded. (Fp)

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Image: Bernd Wachtmeister