The outcome of the study by Huijser is that natural causes play a dominant role in recent global warming, according to the analysis presented. Specifically, the study concludes that roughly two-thirds of observed global warming should be attributed to natural factors, mainly those that increase incoming solar radiation—such as changes in cloud cover and surface albedo—rather than solely to anthropogenic greenhouse gas emissions.
The study challenges the standard Anthropogenic Global Warming (AGW) hypothesis that attributes warming exclusively to human-caused greenhouse gas emissions.
Analysis using satellite-based top-of-atmosphere (TOA) radiation data and ocean heat content measurements indicates that the increase in warming aligns more closely with an increase in incoming shortwave solar radiation (SWIN) rather than with the rise in GHG concentrations alone.
Arguments suggesting the increase in solar radiation is secondary feedback due to GHG-induced warming are considered quantitatively insufficient, according to the paper.
Based on the presented evidence, about a third of warming is attributed to GHGs, and about two-thirds to natural solar-related factors, resulting in a lower climate sensitivity to greenhouse gases than the values suggested by IPCC models.