77 countries have committed to reaching “net-zero” emissions by 2050 . What exactly does this mean?
“Net-zero” means that we keep the overall amount of greenhouse gas in the atmosphere the same [6,7,8]. Greenhouse gas emissions come from many sources including energy generation (59% of global CO2 emissions), transport (16%), and agriculture, land use and forestry (8%) . In many cases we can reduce emissions from these industries, for example by using low-carbon energy sources, like nuclear and renewables [3,12,13,16].
However, to stop temperatures from continuing to rise we need to have zero CO2 emissions overall [4,7]! It’s not possible to bring emissions from all these processes down to zero . But we don’t want to stop doing all the things that cause emissions either! We need another solution, and taking CO2 back out of the atmosphere could be the answer . To reach “net-zero”, any greenhouse gas that we release must be removed again [6,7,8].
Each country’s net-zero commitment has its own terms and conditions [14,15]. For example, the UK’s commitment excludes emissions from: international flights and shipping, UK overseas territories, burning of biomass like wood and chicken litter for energy production, and critically, production of goods and services imported from other countries .
Counting only emissions produced directly from your own country is standard practice . This raises the concern that richer countries like the UK could reach net-zero whilst encouraging emission production in other countries .
 https://sdg.iisd.org/news/77-countries-100-cities-commit-to-net-zero-carbon-emissions-by-2050-at-climate-summit/ See: Penultimate paragraph
 https://ourworldindata.org/co2-and-other-greenhouse-gas-emissions#co2-emissions-by-sector See: Carbon dioxide (CO2) emissions by sector
 https://ourworldindata.org/co2-and-other-greenhouse-gas-emissions#co2-intensity-of-economies See: CO2 intensity of economies
 http://wedocs.unep.org/bitstream/handle/20.500.11822/26895/EGR2018_FullReport_EN.pdf?sequence=1&isAllowed=y See: Section 3.2.3, paragraph 3
 https://www.ipcc.ch/site/assets/uploads/2018/02/SYR_AR5_FINAL_full.pdf See: Box 3.3, page 89
 http://www.lse.ac.uk/GranthamInstitute/news/what-is-net-zero/ Paragraph 3
 https://www.theccc.org.uk/wp-content/uploads/2019/05/Net-Zero-The-UKs-contribution-to-stopping-global-warming.pdf See: Should the net-zero target be for CO₂ or all GHGs?
 https://www.ons.gov.uk/economy/environmentalaccounts/articles/netzeroandthedifferentofficialmeasuresoftheuksgreenhousegasemissions/2019-07-24 See: They exclude emissions or removals from
 https://www.theccc.org.uk/wp-content/uploads/2019/05/Net-Zero-The-UKs-contribution-to-stopping-global-warming.pdf See: 4. Equity considerations, Box 3.3
 https://www.carbonbrief.org/in-depth-qa-the-uk-becomes-first-major-economy-to-set-net-zero-climate-goal See: What about emissions embedded in imports?
 https://pubs.rsc.org/en/content/articlehtml/2018/ee/c7ee02342a See: 13.2 The value of CCS
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