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Aerosol Removal and Solar Decline Drive Post-1980 Surface Warming Acceleration
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Authors
Pochender Shenigarapu 
Abstract
Standard climate models do not fully reproduce post-1980 surface warming acceleration. Two forcing pathways explain the gap: Western clean air legislation progressively removed industrial sulphate aerosols from 1980 onward, unmasking suppressed greenhouse warming; and the Sun's magnetic output declined secularly after 1980, partially offsetting that unmasking. We quantify both using MERRA-2 sulphate aerosol optical depth records for four industrial regions, a first-principles radiative transfer calculation of aerosol forcing efficiency (RE = −25 W/m²/AOD), and a PMOD/NNLSSI2 composite solar irradiance record with 11-year cycle smoothing. North American and European sulphate AOD fell 53% and 67% respectively over 1980–2020, contributing +0.162 W/m² of net warming. The solar secular decline contributed −0.169 W/m² of cooling. Together with greenhouse gas forcing (+1.500 W/m², validated against IPCC AR6 to within 1.3%), these terms form a five-term Resultant Radiative Imbalance Curve (RRIC) of +1.493 W/m² at 2020. The RRIC predicts +0.747°C of warming from 1980, matching HadCRUT5 observations of +0.740°C to within 0.007°C — a result that present GHG-only frameworks do not achieve at this temporal resolution. Extended to 2075 under SSP2-4.5 and SSP3-7.0, the framework projects Paris 1.5°C threshold crossings between 2030 and 2037. Models that ignore aerosol unmasking and solar secular decline do not simply underperform — they misread the physical structure of post-1980 warming.
DOI
https://doi.org/10.31223/X5CR25
Subjects
Physical Sciences and Mathematics
Keywords
Aerosol radiative forcing, Solar variability, Aerosol optical depth, Radiative forcing, Climate projections
Dates
Published: 2026-04-06 08:51
Last Updated: 2026-04-06 08:51
License
CC BY Attribution 4.0 International
Additional Metadata
Conflict of interest statement:
None
Data Availability:
All datasets used in this study are publicly accessible. MERRA-2 sulphate aerosol optical depth (M2TMNXAER v5.12.4, variable SUEXTTAU) is available from the NASA Goddard Earth Sciences Data and Information Services Centre at https://disc.gsfc.nasa.gov/datasets/M2TMNXAER_5.12.4/summary and via the NASA Giovanni interface at https://giovanni.gsfc.nasa.gov/giovanni/ (select dataset M2TMNXAER, variable SUEXTTAU). The PMOD composite total solar irradiance record is available at https://www.pmodwrc.ch/en/research-development/solar-physics/tsi-composite/ For the Data Availability Statement, we may have to use the main page URL since some browsers block FTP links directly. The NNLSSI2 solar reconstruction is available from the NOAA National Centers for Environmental Information at https://www.ncei.noaa.gov/products/climate-data-records/solar-spectral-irradiance. HadCRUT5 global mean surface temperature (v5.0.1.0) is available from the UK Met Office Hadley Centre at https://www.metoffice.gov.uk/hadobs/hadcrut5/data/HadCRUT.5.1.0.0/download.html Mauna Loa atmospheric CO₂ monthly means are available from the NOAA Global Monitoring Laboratory at https://gml.noaa.gov/ccgg/trends/data.html. The Multivariate ENSO Index v2 is available from NOAA ESRL at https://psl.noaa.gov/enso/mei/. CMIP6 SSP greenhouse gas concentration scenarios are available from the Reduced Complexity Model Intercomparison Project at https://rcmip-protocols-aa.readthedocs.io/en/latest/protocol.html. Solar spectral irradiance data (GSFC SSI2, 120–500 nm; NNLSSI1, 700–200,000 nm) were obtained from the LASP Interactive Solar Irradiance Datacenter (LISIRD) at https://lasp.colorado.edu/lisird/data/gsfcssi2/ and https://lasp.colorado.edu/lisird/data/nnlssi/ respectively.
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