Acceleration After 2020 of Decreasing Earth Albedo from DSCOVR-EPIC 2015–2025 Compared with CERES 2000–2025

Abstract. The 10-year Earth albedo time series, its seasonal and wavelength dependence (10 wavelengths from 317.5 to 779.5 nm) of the illuminated Earth are estimated from radiance measurements by the Earth Polychromatic Imaging Camera EPIC located in an orbit around the Earth-Sun Lagrange-1 point L₁. The measurements were made at a backscattered observing phase angle ranging from 2° to 12°. The maximum albedo occurs at 340 nm, ranging from 0.33 in June to 0.38 in December. For shorter wavelengths, 325 and 317.3 nm, the albedo decreases sharply because of ozone absorption. For wavelengths longer than 340 nm (388, 443, and 551 nm) the albedo decreases gradually until about 680 nm where reflectivity from vegetation increases (680 and 779.5 nm). The maximum albedo occurs in December when the illuminated Antarctic ice sheet is observed. The EPIC solar flux weighted annual mean albedo in 2016 is estimated to be 0.298 (317.5 to 779.5 nm) and 0.293 in 2025, (-1.68% change) compared to the Clouds and the Earth's Radiant Energy System (CERES) 2016 values of 0.289 and 0.284 in 2025 (-1.73% change) for the spectral range 300 to 5000 nm. The long-term trend of CERES albedo R_AC (2000–2025.7) = -0.094±0.0007% yr^-1 for a total linear change of 2.35% over 25 years, However, the albedo shows an accelerating decline after 2020, R_AC (2020–2025.7) = ­0.27 ± 0.001% yr^-1 compared to R_AC (2000–2020) -0.09 ± 0.0006% yr^-1. Because the decline is non-linear, the total 25-year change is -2.7%. EPIC observes similar rates of albedo decline, R_AE (2016–2019.5) = -0.18 ± 0.0006% yr^-1 and R_AE (2020.3–2025) = ­0.25 ± 0.001% yr^-1 validating the increased rate of albedo decline after 2020. This suggests that the accelerating reduced Earth reflection of sunlight back to space is enhancing global warming.