Carbon budgets and footprints: a guide

World map showing transfers of emissions

Global emission transfers between countries in 2004 in millions of tonnes of CO2 (MtCO2), taken from Figure 1 in Davis and Caldeira 2010*. (via Carbon Brief)

Greater Manchester Climate Network, with Green Drinks, organised a session called “Carbon Jargon Buster Workshop”. It was addressed by Joe Blakey from the University of Manchester. Joe has specialised in understanding the various methods and tools of carbon accounting, with particular reference to the assumptions behind them. He gave a very comprehensive, clear and stimulating talk to climate activists who had asked for input on the topic. SLIDES

Key take-away messages were:

  • Our carbon footprint is a way of taking stock of our (collective) responsibility for emissions.
  • As many people have a hand in the production of emissions across the planet
    there is no ‘correct’ way of measuring them.
  • Typically it is ‘direct’ emissions and those from energy use that are estimated and presented.
  • Carbon budgets are a tool for planning what carbon we use when, to limit
    the build-up of carbon in the atmosphere over multiple years. A carbon diet
    plan or ration.
  • Carbon budgets depend on estimates of the safe level of global warming (an arbitrary figure, 1.5 or 2 degrees, for example) and the likelihood of the quantity of emissions in the budget keeping us within that level. They also differ in the assumptions they make about the possibility of taking carbon back out of the atmosphere in the future.
  • We need to focus on year-on-year emissions rather than just target dates.
  • By focussing on emissions beyond direct, or territorial ones (consumption, investment, travel, trade) more levers can be found for reducing our contribution to global
  • By continuing to “claim” a carbon budget of (for the city of Manchester) 15 Megatonnes (of Carbon Dioxide equivalent), we are actually reducing the emission space available for poorer countries, which unlike us have not made significant contributions to the climate problem. While making radical cuts is difficult, we should really be thinking of even more stringent targets.

See the slides from Joe’s talk, click HERE

There is also a video of Joe’s talk (Manchester Climate Emergency, thanks to Marc Hudson and Amy Baron).

* Link for the graphic on global emission transfers: Davis, S.J. & Caldeira, K. (2010) PNAS (open access) at,

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