Radiative forcing imbalances are predominantly elicited by anomalies and trends in surface solar radiation, which is modulated by aerosol and cloud albedo.

New research indicates that from 1750 to present there was a total net -10.95 W/m² surface radiative forcing (RF) over South Asia. This negative radiation imbalance – a cooling effect – has been primarily attributed to aerosol/cloud interactions.

This surface RF value includes a +8.99 W/m² increase in shortwave absorption over this 275-year period.

The study thus highlights the “dominant role of aerosol/cloud interactions in cooling at both the TOA [top of atmosphere] and surface.”

Image Source: Sharma et al., 2026

Compare these RF values linked to aerosol/cloud interactions to the five times smaller +1.82 W/m² total forcing said to be derived from CO2 increases since 1750 (Feldman et al., 2015).

Image Source: Feldman et al., 2015

Globally, the increase in absorbed solar radiation due to aerosol/cloud interactions was estimated (Ohmura, 2009) to be +12 W/m² from 1920s-1950s, -8 W/m² from the 1950s-1980s, and +8 W/m² from the 1980s to 2000s.

The magnitude of these surface RF values relative to that alleged for CO2 forcing underscores the the dominance of decadal trends in surface solar radiation in shaping climate.

Image Source: Ohmura, 2009