There is hardly any carbon budget left, which means there can be no delay in action. Emissions must decrease as fast as conceivably possible in rich countries, followed by likewise unprecedented rapid reduction rates also in poor countries – enabled by significantly enhanced support from richer countries for climate mitigation, resilience building, adaptation and Loss and Damage provisions.
The IPCC 2018 special report on 1.5°C estimates the remaining carbon budget for a 67% chance of keeping below 1.5°C global average heating to 420 Gt from 2018 onwards. This only corresponds to 8,5 years at current global emissions levels. The UNEP Emissions Gap report concludes that there will need to be 7.6% yearly reductions globally to have a decent chance (67% probability) to keep below 1.5°C by 2100 while still allowing for higher temperatures (overshooting) before that. With no overshooting and less risk acceptance, global reduction rates must be much higher.
For countries with higher capacity and historical responsibility for having caused emissions, the rate of yearly GHG reductions would clearly need to be significantly higher than this global average rate (likely somewhere between 10 and 20% per year), and including scaled-up contributions of climate finance toward mitigation in poorer countries.
The climate crisis is all about what we do now – immediate behavioural and lifestyle changes to reduce consumption, particularly by the rich and powerful; immediate regulations, bans of dirty infrastructure like coal power stations, standards and policies; immediate planning and investments in renewables, and energy and resource efficiency solutions in all sectors in order to have them play out over coming years and decades to move to 100% renewables, ideally well before 2050. There is no scope for delay.