COM/ENV/EPOC/IEA/SLT(2021)3
19
2. Context and background 2.1. A brief rationale for net-zero and net-negative emissions The 1992 United Nations Framework Convention on Climate Change (UNFCCC) set an ultimate objective to achieve a “stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system” (UNFCCC, 1992[15]). However, the 2021 Working Group I contribution to the Sixth Assessment Report of the IPCC indicates that human activities have unequivocally caused a continued increase in GHG concentrations in the atmosphere, with rapid and widespread changes across the climate system already affecting many weather and climate extremes in all regions across the globe (IPCC, 2021[4]). The 2015 Paris Agreement set a goal of “holding the increase in the global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial levels, recognising that this would significantly reduce the risks and impacts of climate change” (UNFCCC, 2016[2]). Limiting global warming to 1.5°C is projected to lead to lower impacts and reduced climate-related risks compared to global warming of 2°C (IPCC, 2018[3]). However, the Working Group I contribution to the IPCC’s Sixth Assessment Report finds that global warming will exceed 1.5°C and 2°C during the 21st century, unless deep and sustained reductions in CO2 and other GHG emissions take place in the coming decades (IPCC, 2021[4]). In the 2018 IPCC Special Report, modelled pathways that limit global warming to 1.5°C with no or limited overshoot see global net anthropogenic CO2 emissions decline by about 45% from 2010 levels by 2030 (40–60% interquartile range) and reach net-zero CO2 emissions by around 2050, with parallel reductions in non-CO2 emissions – see Figure 2.1. Net-zero GHG emissions would only be reached around 2061– 84 depending on the pathway (IPCC, 2018[3]). On a similar note, the first output of the Sixth IPCC Assessment Report notes that in scenarios that start in 2015 and have very low and low GHG emissions, limiting global warming to between 1°C to 2.4°C by 2100 requires CO2 emissions to decline to net-zero around or after 2050, followed by varying levels of net-negative CO2 emissions, alongside deep reductions in other GHG emissions, in particular methane emissions (IPCC, 2021[4]).
UNDERSTANDING COUNTRIES’ NET-ZERO EMISSIONS TARGETS Unclassified
