A leading global organic group has attacked a study that claims large-scale organic farming has increased greenhouse gas emissions, labelling its analysis 'simplistic' and its conclusions 'clearly wrong'. 

The International Federation of Organic Agriculture Movements (IFOAM) issued a response to the study Does certified organic farming reduce greenhouse gas emissions from agricultural production?, which was authored by Julius McGee, a sociologist at the University of Oregon.

McGee was quoted by British media outlet Mailonline.co.uk as saying his analysis found the rise of certified organic production in the U.S. was not correlated with declines in greenhouse gas emissions derived specifically from agricultural production.

"On the contrary [it] is associated positively overall agricultural greenhouse gas emissions," he was quoted as saying.

"The big questions are what are we are doing when we shift from conventional to organic production and what are the environmental consequences.

"This study says that the organic farming industry is in the early stages. So far we don't see any mitigating effect on greenhouse gasses."

IFOAM, which describes itself as the worldwide umbrella organization for the organic agriculture movement representing nearly 800 affiliates in 117 countries, heavily criticized the paper, saying 'correlation does not prove causation'.

"Most correlations are coincidences. Causation needs to be proved to show that the correlation is not a coincidence," IFOAM said.

"The paper offers no proof of causation; only data-free assumptions.

"It would be more logical to use the same methodology to show that the rise in GMO [genetically modified organism] farming in the US correlates with the increase in greenhouse gases from farming; given that GMO farming now comprises a substantial part of US production while organic farming is only one percent."

IFOAM cited a range of sources to refute findings of the study, which was published in the journal Agriculture and Human Values.

"There is a good body of peer-reviewed science clearly showing that not only does organic farming emit less greenhouse gases, because it captures CO2 and stores it in the ground as soil organic matter, organic farming also reduces greenhouse gas emissions," the organization said.

The organic association took issue with one of the paper's 'date-free assumptions' that the increase in large-scale organic farms was contributing to the increase in greenhouse gases because of the need for machinery.

IFOAM cited the study of the Rodale Farming Systems Trial in the U.S., a long-term comparison trial of conventional and organic systems, which found organic systems use less fossil fuels and emit 30% less greenhouse gases.

The group added that the majority of greenhouse gases in farming came from the use of nitrogen fertilizers, not from farm machinery emissions.

"Synthetic chemical fertilisers are significant contributors to climate change in terms of the energy used to manufacture them and their contribution to nitrous oxide (N2O) and methane (CH4)," it said.

"Nitrous oxide is one of the most significant of the greenhouse gases emitted by agriculture. One N2O molecule is equivalent to 310 carbon dioxide (CO2) molecules in its greenhouse effect in the atmosphere. It has a mean residence time in the atmosphere of 120-150 years and also contributes to the depletion of the ozone layer in the atmosphere."

"The biggest contributor to human-produced N2O pollution is the use of synthetic nitrogen fertilisers such as urea and ammonium nitrate in agriculture. The contribution of nitrogen fertilizers is even higher when all the CO2 and N2O that is emitted in the production of these energy-intensive fertilisers are included in the totals."

It added that since synthetic nitrogen fertilizers were not used in organic farming, the rise in organic farming in the U.S. could not be the cause of the rise in greenhouse gas emissions that come from farming.

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