The trend towards having bigger cars is taking its toll on the environment, according to a new report from the EPA.
The study highlights the fact that the increase in transport emissions, particularly on the roads, is the largest in any sector - at 160% of 1990 figures.
Energy emissions made up almost a quarter of our greenhouse gases in 2005, although agriculture remains the single largest contributor at 28%.
Ireland now has one of the highest rates of carbon emissions per head of population in the world.
Oisin Coughlan of Friends of the Earth said that we can all take steps to help reduce the problem.
"The funny thing is though this is a global problem that the small things each of us do make a difference.
"They reduce the amount of energy we need and reduced the amount of carbon dioxide going into the atmosphere and therefore they reduce the amount of global warming," he said.