1. Climate change: atmospheric carbon dioxide | NOAA Climate.gov. Accessed November 2, 2021. https://www.climate.gov/news-features/understanding-climate/climate-change-atmospheric-carbon-dioxide.
2. COP 21 | UNFCCC. Accessed October 18, 2021. https://unfccc.int/process-and-meetings/conferences/past-conferences/paris-climate-change-conference-november-2015/cop-21.
3. Net Zero in the UK | Shell United Kingdom. Accessed October 19, 2021. https://www.shell.co.uk/a-cleaner-energy-future/our-response-to-climate-change/net-zero-in-the-uk.html.
4. BP sets ambition for net zero by 2050, fundamentally changing organisation to deliver | News and insights | Home. Accessed October 19, 2021. https://www.bp.com/en/global/corporate/news-and-insights/press-releases/bernard-looney-announces-new-ambition-for-bp.html.
5. ExxonMobil announces emission reduction plans; expects to meet 2020 goals. Accessed October 19, 2021. https://corporate.exxonmobil.com/News/Newsroom/News-releases/2020/1214_ExxonMobil-announces-2025-emissions-reductions_expects-to-meet-2020-plan.