Former officials in the UN’s farming wing have said they were censored, sabotaged, undermined and victimised for more than a decade after they wrote about the hugely damaging contribution of methane emissions from livestock to global heating.

The allegations date back to the years after 2006, when some of the officials who spoke exclusively to the Guardian on condition of anonymity wrote Livestock’s Long Shadow (LLS), a landmark report that pushed farm emissions on to the climate agenda for the first time.

LLS included the first tally of the meat and dairy sector’s ecological cost, attributing 18% of global greenhouse gas emissions to livestock, mostly cattle.

The new report’s methodology had produced more accurate figures because “we have access to better data and tools and the IPCC calculations for emissions are also being improved and updated regularly”, she added.

Jennifer Jacquet, professor of environmental science at the University of Miami, suggested it was “no coincidence” that the FAO had rowed back on its appraisal of farm emissions, given the pressures recounted by former officials.

It has also, for the first time, set itself the aim of trying to outline how food systems must change for the world to stay within the globally agreed goal of limiting temperature rises to 1.5C above pre-industrial levels.

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