The US used backstage diplomatic maneuvers to help block the appointment of a scientist from Iran to a key position on the Intergovernmental Panel on Climate Change (IPCC), a leaked diplomatic cable reveals.

The US privately lobbied IPCC chair Dr Rajendra Pachauri, as well as the UK, EU, Argentina and Mali representatives, and had put its embassies to work from Brazil to Uzbekistan. It wanted to prevent the election of Dr Mostafa Jafari as one of two co-chairmen of a key working group.

The other co-chair was to be an American scientist, Prof Christopher Field. The US state department noted that sharing the IPCC position with an Iranian would be "problematic" and "potentially at odds with overall US policy towards Iran".

The jobs often involved travel to and extended residencies in each other's countries, the cable said. The appointment of an Iranian would also "significantly complicate" US funding for the IPCC secretariat for that working group. US diplomats recognized Jafari as "a highly-qualified scientist ... but he is also a senior Iranian government employee".

Pachauri today rejected any suggestion he had colluded with the US private approaches, which apparently ended in another candidate, an Argentinian, being appointed to the position to which Jafari had been nominated. A spokesperson for Pachauri said that he, "neither influenced, nor agreed to influence, the election. Not only would such an agreement be outside his mandate as chairman of the IPCC, but it would also be impossible to achieve."

The cable claims: "Prior to arrival in Geneva, the [US delegation] contacted IPCC chairman Dr Rajendra Pachauri (please protect) who agreed to work on this issue to avoid the potential for disruption to one of the organization's three core working groups." The phrase "please protect" is used to tell the cable's recipients not to use a contact's name publicly.

The US also lobbied the Austrian who was the EU's representative on the committee which "manages the election process". US officials were optimistic, saying he "showed an understanding of US equities". They also tried to persuade Mali to nominate a candidate for the position, as well as the Argentinians. The German, British and Dutch delegations were all pressured to help the US.

Earlier this year, the IPCC – which was set up to review and assess the scientific evidence on climate change and report back to governments – accepted the need for fundamental reform after the disastrous handling of a mistake in the IPCC's last major report, which wrongly stated that all glaciers in the Himalayas would melt by 2035. That public relations catastrophe was attributed to the IPCC's tiny communications staff, but the revelation that the US manipulated the appointments process presents a more fundamental challenge as the IPCC's governing principles (pdf) state its role is "to assess on a comprehensive, objective, open and transparent basis" information related to human-induced climate change, on behalf of the world's governments.

According to the cable, sent on 2 September 2008 in the name of Condoleezza Rice, the then US secretary of state, the US delegation to the IPCC was "working actively" to prevent the election of Jafari, "who has represented Iran in international negotiations".

Jafari and Field were the only candidates specifically nominated (pdf) for the co-chair positions on one of the three core working groups of the IPCC. It is standard IPCC practice for one co-chair to be from a developed country and the other from a developing country.

The confidential cable put diplomatic missions in capitals around the world on standby to help the US IPCC delegation (USdel) "secure a positive outcome" in blocking Jafari's nomination.

The cable was sent two days before the end of the IPCC plenary at which the appointments were made, at the end of the day on which Pachauri was re-elected as chair (pdf). It predicted: "Based on experience at prior IPCC plenaries, events ... will likely unfold unpredictably and rapidly, necessitating a rapid and flexible USG [US government] response."

In the event, Field was elected alongside an Argentinian candidate as co-chairs of the second of the three working groups that write the IPCC's influential reports. Jafari was appointed in June 2010 to a far more junior position, as one of 15 "lead authors" on a chapter for the third working group's report (pdf), due to be published in 2014. He had already served as a lead author for the previous IPCC report, which was published in 2007 and is credited with convincing the world's governments that human activities were very likely to be causing global warming. The report helped win the IPCC that year's Nobel peace prize alongside former US vice-president Al Gore.

The state department was aware of the sensitivity of its delegation's efforts, ordering their missions not to contact their host countries' diplomats "until such a call is received" as "USdel will be interacting directly with host-country expert delegations in Geneva, and premature contacts ... could be highly counterproductive".