Against a population of 100 million: 1) Only 10% of Canada is inhabitable. 2) Our agricultural lands are limited and huge amounts of it have already been covered over by housing developments near Toronto and Vancouver; tripling our population will cover most of the rest, contributing to food insecurity. 3) Between the offshoring of manufacturing, information technology and even call centre jobs, and automation replacing ever more remaining manufacturing and retailing jobs and increasing numbers of highly skilled jobs in the next 20 years, what employment will exist for millions more Canadians? 4) If Canada's immigration were not based on the nepotism of limitless family class sponsorships, regardless of education, skills etc., we'd have greater innovation and other benefits by now. 5) Climate change.  Three decades of massive immigration that is overwhelmingly from low carbon footprint countries means that Canada has created millions of First World consumers to burden the planet.