Council leaders have blamed the severe winter and tasks linked to the general election campaign for failing to meet a target to reduce CO2 emissions.
Since 2004, Highland Council said it had successfully cut energy use.
But prolonged cold weather at the start of the year led to greater heating costs and carbon emissions.
Officers also blamed election duties, such as travelling by electoral assessors, for adding to mileage costs and the level of emissions.
The local authority had aimed to cut carbon emissions over the 2009-10 financial year by at least 4.24% as it had done over the past two years.
However, it only succeeded in achieving a reduction of 1.09%, or 746 tonnes of C02.
In a new report to the council's resources committee, officers said an "exceptionally cold" winter had hampered progress.
They said December 2009 and January and February this year were 2C colder than for the same period in 2007-08 and 2008-09.
In January, the temperature in Altnaharra, near Lairg in Sutherland, dropped to -22.3C, making it the coldest place in Britain this winter.
Altnaharra shares the record as the coldest place in the UK with Braemar after recording -27.2C in 1995.
Officers said in their report: "A significant challenge towards energy use and emission reductions is the prevailing climate of the region."
They added: "In 2009-10 the UK experienced a sustained period of cold weather and in the Highlands records show the coldest January and February since 1986."
Highland Council said it had been striving to reduce councillors' and staffs' mileage.
However, the report showed 29,617 extra miles were totted up in the countdown to May's general election.
The papers also detail areas of success.
Installing water meters at a hundred of the local authority's main buildings have reduced emissions linked to water consumption by 51% since 2007-08.
This resulted in savings of £391,813 for the council.
- 13 August 2010
- 12 March 2010
- 2 February 2010
- 8 January 2010