Jonathan Cullen of Cambridge University said the world is not about to run out of energy or materials but something must nevertheless be done to stop and even reverse the rise in anthropogenic carbon dioxide in the atmosphere. Since 1870, human activity has added 1500 gigatonnes of CO2 to the atmosphere and this has raised global temperatures by about 1oC. These carbon emissions have arisen in the course of improving the thermal comfort, sustenance, illumination and hygiene for the growing population; to move them and their goods around, and to make buildings, infrastructure vehicles and “things”. With current emissions running at 28 Gt CO2/year, 35% is arising from industry, 27% from transport and 31% from buildings.
Using Sankey diagrams to map energy flows and CO2 emissions from source to final product or service Dr Cullen showed that compared with buildings and transport, industry uses energy more efficiently. Within industrial products, steelmaking emitted most CO2 (25%) with cement (19%), paper (4%), plastics (4%) and aluminium (3%) being the other big consumers. However 45% of total industrial emissions were in the Others category. Global demand for these materials will double by 2050 and the scope for reducing their process emissions is limited by the fact that most producers are now approaching the “best practice” limits. To reach the desirable halving of absolute CO2 emissions by 2050, a cut of at least 75% per tonne of product is needed and this appears impractical on current technologies.