This approach was originally developed at the University of Utrecht (Blok et al. 1997) to share the emission allowances of the first commitment period within the European Union. It has been updated and revised subsequently (Phylipsen et al. 1998, Groenenberg 2002, den Elzen and Lucas 2003, Höhne et al. 2003, Phylipsen et al. 2004, Höhne et al. 2005a, Höhne 2006).
Analogue to the first Triptych approach, the global Triptych approach is a method to allocate emission allowances among a group of countries based on several national indicators. It takes into account main differences in national circumstances between countries that are relevant to emissions and emission reduction potentials. The Triptych approach as such does not define which countries should participate, but hopefully it is applied to all countries equally.
If the approach is applied globally, substantial reductions for the industrialised countries, especially those with carbon intensive industries (i.e. Eastern Europe and Russian Federation), are required. Substantial emission increases are allowed for most developing countries. But for lower concentration targets (e.g. 450 ppmv CO2) these are rarely above Business As Usual (BAU) emissions.
The Triptych methodology calculates emission allowances for the various sectors which are added to obtain a national target. Not individual sector targets but only the national targets are binding. This provides countries the flexibility to pursue any cost-effective emission reduction strategy.
The emissions of the sectors are treated differently: For ‘electricity production’ and ‘industrial production’, a growth in the physical production is assumed together with an improvement in production efficiency. This takes into account the need for economic development but constant improvement of efficiency. For the ‘domestic’ sectors, convergence of per capita emissions is assumed. This takes into account the converging living standard of the countries. For the remaining sectors, ‘fossil fuel production’, ‘agriculture’ and ‘waste’, similar reduction and convergence rules are applied.
Details on the applied methodology can be found in Phylipsen et al. 2004. The choice of parameter values is subjective but should reflect a reasonable burden sharing of emission reductions. Several other options are possible.
The Department for Environment Food and Rural Affairs (DEFRA – United Kingdom)*, in their Report (pg18) chose parameters to be balanced in stringency over the sectors for the stabilisation levels of 450 and 650 ppmv CO2eq. In other scenarios they put forward, e.g. for 550 ppmv CO2eq, the chosen parameter set is valid for both years, 2020 and 2050, but does not allocate emission reduction efforts evenly over all sectors.
The parameters for the 650 ppmv case are relatively moderate: 40% to 50% share of renewable and emission-free electricity in 2050, 20% to 40% reduction in electricity generation based on coal and oil as well as convergence of all countries’ industrial energy efficiencies to a level that is 5% to 30% better than best available technology in 1995.
The parameters for the 450 ppmv case stretch the methodology to the limit: 70% to 95% renewable and emission-free electricity in 2050, 70% to 95% reduction in electricity generation from coal and oil, convergence to an industrial energy efficiency that is 50% to 70% better than best available technology in 1995.
* Niklas Höhne, Dian Phylipsen, Sara Moltmann, Factors underpinning future action 2007 update, Department for Environment Food and Rural Affairs, United Kingdom.
The complete report including the section on Global Triptych is available here