Party energy spokesman Liam McArthur hit out at the Scottish Government over its support for a third runway, as the Scottish Lib Dems backed an emergency motion in favour of rail as an alternative to expanding Heathrow.
The UK Government has already announced it is in favour of a third runway being built at the airport.
SNP ministers support this, claiming such a move could create up to 16,000 new jobs north of the border and reduce landing charges paid by airlines operating between there and Scotland.
But the motion, passed at the Scottish Liberal Democrat Autumn conference in Dunfermline, Fife, said that “climate change and the resulting environmental destruction represents one of the biggest threats to our way of life”.
Building another runway at Heathrow will “contribute to both of the above”, it added, while arguing going by train is “environmentally more benign that air travel”.
Mr McArthur said: “The voice of the Scottish Liberal Democrats couldn’t be clearer. Our commitment to protecting the environment has been reinforced by the passing of this afternoon’s motion opposing Heathrow expansion.
“Instead of prioritising low carbon transport, the SNP have backed an option that will increase the number of damaging short-haul flights.
“Our parliamentary questions have revealed that they did so without even assessing the impact that this would have upon Scotland’s environment.
“The SNP have chosen to fly an Airbus A380 through Scotland’s climate change commitments by backing the expansion of Heathrow.”