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Carbon Dioxide stabilisation lines

These emissions pages discuss targets for the UK. To give meaning and perspective to these targets I have run the Global Commons Institute's "Contraction & Convergence" model to see what fair emission targets would look like for the UK. I have run the model to stabilise atmospheric carbon dioxide (CO₂) concentrations at both 450 ppm or 750 ppm by the year 2200. These stabilisation targets match those discussed in the consequences pages.

See below for more detail about the "Contraction & Convergence" (C&C) model. Note that the purpose of the model is to suggest a fair way of splitting future carbon emissions, between richer and poorer countries.

• The following plot shows data taken from the model runs and combines it with actual emissions data from CDIAC (the Carbon Dioxide Information Analysis Centre), from 1800 to 1989. From 1990-2008 data are from the NAEI (National Atmospheric Emissions Inventory), which now reports statistics to DECC (the new Department of Energy and Climate Change).
• Notice that the "hump" in the 750 ppm trend is just part of the model design.
• Also note that the figures are in millions of tonnes of CO₂ emitted per year, e.g. in 1990 we emitted 593 Mt.

Global Commons Institute (GCI) model of "Contraction & Convergence"

Climate change is obviously a global problem. The GCI came up with a fair solution which is called Contraction & Convergence (see GCI's Carbon Countdown document).

The basic premise is that economically well developed countries, with high emissions (e.g. Western Europe and USA), will cut down between now and 2030. Less well developed countries can grow their economies (and hence emissions) up to this convergence point, which is only fair. At this convergence point all countries will have the same emissions per capita (i.e. per person), and so from there we all cut down together. See the following:

This model can be run to hit various future target levels of carbon dioxide concentration in the atmosphere. I have run the "200 countries" version of the model to work out what the UK targets would be for: 450 ppm and 750 ppm CO₂ stabilisation in the atmosphere by 2200. In both cases the convergence year was set to 2040.