Urban surfaces (roofs, pavements) with high solar reflectance (albedo), defined as cool surfaces, reduce solar energy absorbed by buildings and pavements, leading to a reduction in air-conditioning use and improved indoor thermal condition in non-conditioned buildings. In addition, cool surfaces improve summertime outdoor environment that in turn yield a better urban air quality, reduce morbidity and mortality. A reduction in cooling energy use reduces demand for electricity generation and lowers CO2 emissions from fossil fuel power plants. Independent of the direct CO2 reduction, high-albedo urban surfaces reflect a greater fraction of solar shortwave radiation back to space and create a negative radiative forcing (RF) that counters the RF induced by accumulation of greenhouse gases (primarily CO2) in the atmosphere. Previously, a method based on equating the RF on top of the atmosphere (TOA) was introduced to calculate a global-averaged CO2 equivalency offset for increasing albedo of urban surfaces. Here, a simplified technique is introduced to calculate a regional CO2-equivalency of changes on albedo of land surfaces. The required input for this technique is the regional global horizontal insolation (GHI) on TOA and on ground surface. Using this simplified model, calculations are carried out for about 4400 weather stations world-wide. These calculations showed that the world-wide median CO2 offset was about 2 kg per 0.01 albedo change of a m2 of a surface. The CO2 offset is highest where the atmospheric transmittance is high. The CO2 offset is about 2–3 kg around the equator, 1.5–4 kg for −30° to −20° latitude and 1–5 kg for 20° to 30° latitude, depending on local cloud cover. This method would allow development of country-specific policies to monetize the effect of high-albedo urban surfaces to counter global warming and climate change.

Hashem Akbari, A simplified method to calculate atmospheric CO2 equivalency for changing surface albedo, Urban Climate, Volume 65, 2026, 102795, ISSN 2212-0955, https://doi.org/10.1016/j.uclim.2026.102795. (https://www.sciencedirect.com/science/article/pii/S221209552600026X).