1. National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Information (2019) Climate at a glance. https://www.ncdc.noaa.gov/cag/global/time-series/globe/land_ocean/ytd/12/1880-2016. Accessed 7 Oct 2019
2. National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Information (2020) State of the climate: global climate report for January 2020. https://www.ncdc.noaa.gov/sotc/global/202001. Accessed 20 Feb 2020
3. Etheridge DM, Steele LP, Langenfelds RL, Francey RJ (2001) Law dome atmospheric CO2 data (1800–1850). https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/antarctica/law/law_co2.txt. Accessed 7 Oct 2019
4. National Oceanic and Atmospheric Administration (NOAA) Earth System Research Laboratory for Global Monitoring Division (2019) Recent monthly average Mauna Loa CO2. https://www.esrl.noaa.gov/gmd/ccgg/trends/. Accessed 7 Oct 2019
5. National Oceanic and Atmospheric Administration (NOAA) Earth System Research Laboratory for Global Monitoring Division (2020) Recent monthly average Mauna Loa CO2. https://www.esrl.noaa.gov/gmd/ccgg/trends/mlo.html. Accessed 20 Feb 2020