It mentioned leaving television on standby and using cars for short journeys as typical energy-wasting practices.
The message was superimposed over an image of a factory emitting fumes with a row of houses in the foreground.
The authority received three complaints challenging the validity of the statement. The complainants asked if the trust could prove that human actions caused half of the UK’s carbon dioxide emissions and said it suggested, misleadingly, that human-generated emissions were responsible for climate change.
The ASA said: “We understood that the ad’s purpose was to raise awareness about energy waste and encourage readers to reduce their carbon dioxide emissions.”
It said the claim was unlikely to mislead readers about the cause or nature of climate change. Scientific opinion, it said, largely accepted that this was exacerbated by man-made carbon dioxide emissions.