In the refund version, the calculations are based on the USA estimated carbon price of circa $15 per ton of CO2. Therefore they implicitly include the impact of the current recession.
No discount for free emission allowances has been applied.
Historical calculations
For the previous version with a global cap, the following sample costs and benefits calculations for 2013 took account the impact of the recession. The annual net emissions growth rate has been discounted to 2% per annum due to the current global slowdown (this is equivalent to skipping one year of growth and using the most conservative previous growth scenarios). An illustrative cap is set at an ambitious 20% reduction in emissions by 2020 from its 2005 level. It applies only to emissions attributable to Annex I countries (current climate change regime). Total baseline emissions in 2005 are rounded to 1 GtCO2, as per the higher estimates and for ease of scaling. Based on the emission growth rate and the emission cap, the levy is calculated as 30% of the carbon price in 2013, translating to approximately 5% of the fuel price.