Posted on noviembre, 25 2009

If we are serious about avoiding catastrophic climate change, we need to limit global warming resulting from increased concentrations of greenhouse gases in the atmosphere. This means limiting and reducing global net emissions. But who must limit their emissions, by how much, and when? This is where a global carbon budget comes in; more precisely – a long-term cumulative GHG allowance for the entire planet.

A global carbon budget can guide and inform our efforts to limit the total amount of greenhouse gases we put into the atmosphere, share the remaining global space equitably, and achieve sufficient effort in the near and medium term so that we don’t leave an impossible task for the next generation in future decades.

OK, sounds interesting. But what exactly is a Carbon Budget?

A Global Carbon Budget sets out the total emissions that humanity is allowed to “spend” over a specific period, and then allocates those allowed expenditures to particular time periods, countries and regions over the period covered by the “budget”.

Science tells us that it is cumulative global emissions in particular long-lived greenhouse gases such as CO2 that drive atmospheric concentration levels and global temperatures, and it will be our total emissions of these gases between now and 2050 that will determine our success in limiting warming to below two degrees. Thus the starting point of a global carbon budget is the total emissions allowed worldwide between now and 2050 to meet a particular objective, such as having a high chance of staying well below 2 degrees C.