Comparing fossil CO2 emissions from vegetable greenhouses in Canada with CO2 emissions from importing vegetables from the southern USA

► Greenhouse heat energy loss is determined mainly by external surface areas. ► Greenhouse floor area increased 35% between 1996 and 2007 in Canada. ► CO2 emissions from Canadian vegetable greenhouses were 0.35 Tg. ► Air transport CO2 emission intensity was 1.9 times that of greenhouses. ► Truck transport CO2 emission intensity was .53 times that of greenhouses.