Career
He is a columnist for many publications, among them, Métro and Transcontinental Media. He has also been columnist for Radio-Canada, CHMP-FM, the magazine Corporate Knights, as well as newspapers Louisiana Presse and Voir. Guilbeault has participated in most international United Nations conventions on climate change.
At age six, Guilbeault, with the approval of his mother, occupied a tree behind his home to prevent it from being cut down by a real estate promoter.
He later studied political science and theology at Université de Montréal for a short period of time (no diploma), where he was president of the political science student association and participated in activities related to the Canadian Human Rights Commission. In 1994 he co-founded Équiterre, a non-profit and non-governmental organization, with the help of Sidney Ribaux, Laure Waridel and François Meloche.
He was in charge of the climate change initiative and research of this organization. He was the president of the Quebec Coalition for Climate Change.
He was the vice-president of the Conseil régional de l"environnement de Montréal.
He also gave conferences on the environment across Canada. In 2005 he participated in a Greenland expedition where he claims to have witnessed the effects of arctic ice melting.