
ALT B.5.3 If the annual CO2 emissions between 2020–2030 stayed, on average, at the same level as 2019, the 7 resulting cumulative emissions would almost exhaust the remaining carbon budget for 1.5°C (50%), and deplete 8 more than a third of the remaining carbon budget for 2°C (67%). Estimates of future CO2 emissions from 9 existing fossil fuel infrastructures without additional abatement42 already exceed the remaining carbon budget 10 for limiting warming to 1.5°C (50%) (high confidence). Projected cumulative future CO2 emissions over the 11 lifetime of existing and planned fossil fuel infrastructure, if historical operating patterns are maintained and 12 without additional abatement43, are approximately equal to the remaining carbon budget for limiting warming 13 to 2°C with a likelihood of 83%44 (high confidence). {2.3.1, 3.3.1, Figure 3.5} 14 15 B.5.4 Based on central estimates only, historical cumulative net CO2 emissions between 1850 and 2019 amount 16 to about four-fifths45 of the to

ALT Emissions Trends and Drivers Chapter 2 The global estimate of future CO₂ emissions from current and planned fossil-fuel infrastructures is 850 (600-1100) GtCO₂ (Tong et al 2019). This already exceeds total cumulative net CO₂ emissions in pathways that limit warming to 1.5°C with no or limited overshoot (see above). It is about the same size as the total cumulative net CO2 emissions of 890 (640-1160) GtCO, from pathways that limit warming to 2°C (<67%) (Chapter 3). Hence, cumulative net CO₂ emissions to limit warming to 2°C (<67%) or lower could already be exhausted by current and planned fossil fuel infrastructure (high confidence) even though this estimate only covers a fraction of all infrastructure developments over the 21st century as present in mitigation pathways, does not cover all sectors (e.g., AFOLU) and does not include currently infrastructure development plans in transport, buildings, and industry due to a lack of data. 2 overall cumulative net CO₂ emissions until reaching




























