Annual emissions budget
How high is the climate-compatible annual emissions-budget of a person?
To determine the climate-compatible emissions-budget of an individual person, it is necessary to first determine the cumulative global level of emissions with which dangerous climate change can be avoided. Having determined the global emissions target, country-level and then individual emissions-budgets can be abstracted. In 2009, the German advisory council for global change (WBGU) carried out a study to determine these targets.
The scientific consensus opinion is, that global warming must be limited to a maximum of 2°C in relation to pre-industrial levels, to avoid dangerous and irreversible consequences of climate change (WBGU 2009, 1). To reach this goal, the sum total of global emissions must be kept within certain limits between now and 2050. To have a 67% chance of keeping the average increase of global temperature at or below 2°C, emissions must be limited to 750 billion tons of CO2 between now and 2050 (and must have levelled off at a very low level by that point). To increase this chance to 75%, emissions need to be limited to 700 bil. t CO2 (WBGU 2009, 2). To keep total global emissions within these limits, the WBGU devised three emissions paths (for different groups of nations). As these paths would, for example, envisage that the group of industrialized nations (such as USA, Europe, Japan but also oil exporting nations such as Saudi-Arabia or Venezuela) reduce their per-capita emissions from 12 t CO2 (current levels) to 0 t CO2 by 2025 (which is of course wholly unrealistic), these emission paths were complemented with flexible mechanisms, such as emissions trading. In the thus modified scenario the group of industrialized nations but also the emerging economies (such as China, Thailand or Mexico) would either purchase emission certificates from and/or implement climate protection projects (i.e. in the framework of CDM) in the group of ‘developing’ countries (such as Burkina Faso, Nicaragua, Vietnam) to offset their emissions. In terms of per-capita emissions, this modified scenario would envisage the groups of industrialized and emerging nations to reduce their emissions (currently around 4,5 t CO2 annually) over the medium term (2025-2030) to around 3 t CO2 annually. The group of ‘developing’ countries would increase their emissions from around 1 t per-capita annually to 2 t per-capita by 2040 (to allow for a certain level of development). By 2050 the emissions of all three-country groups would level off at 1 t per-capita annually (with slightly higher emissions for the group of emerging economies, and slightly higher emissions again for the group of ‘developing’ countries, to account for historic responsibility of emissions by industrialized nations) (WBGU 2009, 3ff).
For us as individuals this means that the average, global per capita (the basis for this calculation is global population data for 2010) emissions can be a maximum of 2,7 t CO2 to avoid dangerous climate change (for context, on a return, economy class flight from Vienna to New York, the per-passenger emissions are 2,8 t CO2). However, emissions in industrialized nations are currently considerably higher, and must be reduced to 1 t CO2 per-capita by 2050.