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May 26th 2010 print

Paul Fraser

CSIRO responds

The methane data were plotted by a non-CSIRO designer in a manner that resulted in about a 20 year lag at the end of the record, presumably to separate them visually from the carbon dioxide record. This should have been explained in State of Climate - unfortunately it was not, and this has lead to Quirk’s misinterpretation of the data.

T. Quirk published a commentary on the CSIRO/Bureau of Meteorology State of Climate ‘snapshot’ in Quadrant Online (19 May 2010). 

In State of Climate, CSIRO presented their 1000-year records1 of the accumulation of carbon dioxide and methane in the atmosphere. Quirk noted that ‘the methane data is [sic] only plotted up to 1990….ten years short of the carbon dioxide measurements’. 

The methane and carbon dioxide data shown in State of Climate are annual means up to and including 2009. The methane data were plotted by a non-CSIRO designer in a manner that resulted in about a 20 year lag at the end of the record, presumably to separate them visually from the carbon dioxide record. This should have been explained in State of Climate - unfortunately it was not, and this has lead to Quirk’s misinterpretation of the data. The data are now correctly plotted on the ‘snapshot’ web-site. 

Quirk noted ‘Methane concentrations have plateaued – this does not fit the CSIRO storyline’. 

This is not correct: the methane data in ‘State of Climate’ show that methane stopped growing in the atmosphere and then started to grow again. Contrary to Quirk’s assertions, the CSIRO greenhouse gas team was the first group in the world to observe, explain and publish the rapid growth of methane in the Southern Hemisphere atmosphere in the 1970s2, the first to explain the role of biomass burning in methane variability3, the first to observe that methane slowed and nearly stopped growing in the early 2000s4,5, due to declining methane sources – in particular leaking natural gas6, the first to advise the IPCC of slowing methane growth rates, and were the first to show that methane started to grow again in the late 2000s7, from natural wetland sources in the Arctic and the tropics. The CSIRO team were the first to model the global distribution of methane, showing the impact of both natural, agricultural and industrial emissions8,9

The CSIRO ‘storyline’ has, in fact, been to report accurately, in a timely manner, what is happening with methane in the atmosphere, and to explain such behaviour in terms of what is known about methane sources and sinks. 

Contrary to Quirk’s assertions, CSIRO has never singled out rice and cattle as the only drivers of the long-term growth of methane in the atmosphere since pre-industrial times. CSIRO have always considered that fossil fuel methane sources (coal and gas) and landfill emissions were major drivers of long-term changing methane levels and concluded that a reduction in this fossil fuel source was a major contributor to the slowing of methane growth rates in the 1990s5,6, leading to the near-halt in methane growth rates in the early 2000s.  

Furthermore, Quick accused CSIRO of ‘wading into a large government funded trough’ and being ‘not inclined to publish anything that gets between it and the trough’. 

CSIRO’s research on the accumulation of carbon dioxide and methane in the background atmosphere has been funded by the Australian government (through CSIRO, BoM and AAD) and by NASA (through MIT) since the early 1970s. This research has produced a record of these greenhouse gases in the atmosphere that is unparalleled world-wide and used today by every important laboratory investigating the drivers of climate change. Six Australian governments during this period (3 Labor and 3 Liberal/National) have been totally supportive of this research, providing consistent and comparable levels of funding, and have never tried to influence its outcomes or suggest to CSIRO what research to publish or not publish. 

The senior CSIRO scientists involved in this research have published several hundred papers on greenhouse gases in international peer-reviewed journals, including Nature and Science; they have received many national and international awards recognising the world-leading status of their research, including the Eureka Prize, the Victoria Prize, and election to the prestigious Australian Academy of Science and the Australian Academy of Technological Sciences and Engineering. 

Dr P. Fraser FTSE, CSIRO Marine and Atmospheric Research

References (CSIRO Greenhouse Gas team in bold) 

1 MacFarling Meure, C., D. Etheridge, C. Trudinger, P. Steele, R. Langenfelds, T. van Ommen, A. Smith & J. Elkins (2006), The Law Dome CO2, CH4 and N2O ice core records extended to 2000 years BP, Geophysical Research Letters, 33 (14), L14810 10.1029/2006GL026152.

2 Fraser, P., A. Khalil, R. Rasmussen & A. Crawford (1981), Trends of atmospheric methane in the Southern Hemisphere, Geophysical Research Letters, 8 (10): 1063-1066.

3 Langenfelds, R., R. Francey, B. Pak, P. Steele (2002), Inter-annual growth rate variations of atmospheric CO2 and its isotope δ13C, H2, CH4, and CO between 1992 and 1999 linked to biomass burning, Global Biogeochemical Cycles, 16, doi: 10.1029/2001GB001466.

4 Steele, P., P. Fraser, R. Rasmussen, A. Khalil, T. Conway, A. Crawford, R. Gammon, K. Masarie & K. Thoning (1987), The global distribution of methane in the troposphere, Journal of Atmospheric Chemistry, 5: 125-171.

5 Steele, P., E. Dluglokencky, P. Lang, P. Tans, R. Martin & K Masarie (1992), Slowing down of the global accumulation of atmospheric methane during the 1980s, Nature, 358, 313-316.

6 Bousquet, P., P. Ciais, P., J. Miller, E. Dlugokencky, D. Hauglustaine, C. Prigent, G. van der Werf, P. Peylin, E.-G, Brunke, C. Carouge, R. Langenfelds, J. Lathiere, F. Papa, M. Ramonet, M. Schmidt, P. Steele, S. Tyler & J. White (2006), Contribution of anthropogenic and natural sources to atmospheric methane variability, Nature, 443, 439-443, doi:10.1038/nature05132.

7 Rigby, M., R. Prinn, P. Fraser, P. Simmonds, R. Langenfelds, J. Huang, D. Cunnold, P. Steele, P. Krummel, R. Weiss, S. O’Doherty, P. Salameh, R. Wang, C. Harth, J. Muhle & L. Porter (2008), Renewed growth of atmospheric methane, Geophysical Research Letters, 35, L22805, doi:10.1029/2008GL036037.

8 Fraser, P., P. Hyson, R. Rasmussen, A. Crawford & A. Khalil (1986), Methane, carbon monoxide and methychloroform in the southern hemisphere, Journal of Atmospheric Chemistry, 4 (1): 3-42, 1986.

9 Fung, I., J. John, J. Lerner, E. Matthews, M. Prather, P. Steele and P. Fraser (1991), Three-dimensional model synthesis of the global methane cycle, Journal of Geophysical Research, 96 (D7): 13033-13065.