• We provide reference forecasts for CO2 emissions in Portugal based on an ARFIMA approach. • Projections allows us to identify the policy effort necessary to achieve IPCC targets. • We forecast a reduction of 17.5% of emissions by 2050 relative to 2010 levels. • carbon neutrality by 2050 requires an additional reduction in emissions of 65.5%. • The long-memory implies that any policy effort to reduce emissions must be persistent.