The data used for the analysis are (i) the monthly ice extent series produced by the National Snow and Ice Data Center (NSIDC) for the Globe, the Northern Hemisphere, and the Southern Hemisphere, from January 1979 to April 2024, and (ii) the monthly snow cover extent series constructed by the Rutgers University Global Snow Laboratory (GSL) for North America + Greenland, the Northern Hemisphere, and Europe + Asia, from January 1967 to April 2024 (no snow extent data are available for the Southern Hemisphere from NOAA, 2024). These series are the result of a collaborative effort between The National Centers for Environmental Information (NCEI) - National Oceanic and Atmospheric Administration (NOAA) and the Rutgers University Global Snow Lab (GSL). All anomalies are relative to the 1991–2020 average. https://www.ncei.noaa.gov/access/monitoring/snow-and-ice-extent/sea-ice/G/6