the science

Runaway climate change would be bad news for hot, dry, forested areas 

A fair share for everyone 

Sea level rise will impact on coastal communities around the world 

C&C model - click to enlarge 

Fair AND square...here comes the science

Contraction & Convergence or 'C&C'

Minimising manmade climate change is almost certainly the biggest challenge faced by humans. Some impacts are happening right now (often in parts of the world least equipped to deal with them) because of greenhouse gases already released into the atmosphere. We have to act quickly and decisively to avoid really dangerous climate effects.

Developed by Aubrey Meyer of the Global Commons Institute, the Contraction and Convergence (C&C) model is a widely accepted global framework for reducing greenhouse gas emissions (GHGs) to safe levels in a socially just way. The model provides a global ‘carbon budget’ with annual reduction targets for CO2 emissions, based on levels considered safe to avert dangerous climate change. Once in the atmosphere, GHGs can take up to 200 years to decay, so to stay within safe levels we'll have to continue to reduce, or ‘contract’ emissions year-on-year, to near zero by around 2080. The diagram (below, right) illustrates the scale of worldwide reductions required to achieve C&C.

Global equity is a governing principle of the C&C model. Historically, levels of emissions have been related to a nation’s wealth. As a result, per capita emissions (‘per person’ averages) in rich countries are well above the global average and in poor countries, well below. In the C&C Framework everyone is given an equal right to emit CO2. In order to resolve current inequalities, individuals in developing countries would initially be entitled to emit relatively more CO2, and those in developed nations relatively less, until per capita emissions from all countries ‘converge’ at an agreed annually reviewed level.

In applying the C&C model, the UK’s permitted emissions have been divided by its projected population to give a per capita figure. This indicates how much carbon individuals within the UK are entitled to emit, otherwise referred to as our individual ‘carbon budget’ or ‘Fair Share’. In 2008 our individual carbon budget has been calculated at just over 4.1 tonnes of CO2 emissions, falling to 3.2 tonnes by 2017.

The C&C model has also been used to work out an overall carbon budget for the South West which again would need to reduce year-on-year. This reveals that in broad terms the region’s current CO2 emissions are approximately 10% above its fair carbon share for 2007 and that CO2 would need to be reduced by nearly a third by 2017 to be ‘within budget’. See the SW budget for more.