regarding "the possibility is very real that Schoeberl and Dessler underestimated the direct radiative water vapour forcing and/or overestimated the effects of aerosol forcing."
Yes indeed! he possibility is very real—and not trivial—that Schoeberl, Dessler, and related 2024–2025 studies (including the APARC/WCRP assessment) underestimated the direct radiative forcing from the ~10% stratospheric water vapor increase and/or overestimated the compensating cooling from the co-injected aerosols.
Key reasons this remains plausible:Aerosol microphysics in models is acknowledged as challenging (e.g., the APARC report itself notes divergences in simulated growth rates, sedimentation, and decay), introducing substantial uncertainty in the negative forcing estimate (~-0.4 to -0.8 W/m² from aerosols).
Water vapor forcing calculations lean on the same core physics as older papers (Forster & Shine, Solomon et al.), which consistently yield positive ~0.2–0.4 W/m² for equivalent perturbations—yet recent works apply reductions or offsets without equivalent sensitivity testing for vapor dominance scenarios.
The eruption's plume was unusually high and water-rich with relatively low sulfur (compared to Pinatubo-class events), so extrapolating aerosol cooling efficacy from canonical volcanic cases may overestimate reflection.
The 10percent increase from Hunga Tunga may be underestimated, with some indications of a 15% global increase for a time.
Observational separation of signals remains difficult amid high interannual variability (El Niño, albedo shifts), allowing room for the net forcing to swing toward mild-to-moderate warming if aerosol effects decay faster or vapor persistence/latitude distribution amplifies greenhouse trapping more than modeled.
Critics (like myself, ha) argue this uncertainty was not symmetrically explored, with the burden placed heavily on proving vapor-driven warming rather than disproving it. Thus, a net positive forcing contribution to the 2023–2024 spike—potentially rivaling or exceeding El Niño/albedo factors—remains a legitimate alternative hypothesis within the bounds of established radiative physics.
It appears to me that Record-low planetary albedo (reduced low-level cloud cover over oceans may have overwhelmed or have been far more contributory to said warming then the less certain ad direct cleaner aerosols from IMO 2020 regulations) With 0.5–1 W/m² extra absorbed solar radiation. (again it is likely that human actions are over estimated)
Likely the El Nino, the record low planetary albedo, (low level cloud cover), which on a decadal scale was a large factor in the multi decadal warming trend, plus Hunga Tunga. all combined for the record warm surge, with Anthropogenic CO2 being a non factor.
I look forward to the day, in maybe a few months, when they have to confront the inconvenient fact that global temperatures are back to where they were almost 30 years ago.
The climate change hoax is imploding in the face of unavoidable reality, with the helpful assistance of President Trump who has just withdrawn from the UN IPCC and the UN FCCC.
regarding "the possibility is very real that Schoeberl and Dessler underestimated the direct radiative water vapour forcing and/or overestimated the effects of aerosol forcing."
Yes indeed! he possibility is very real—and not trivial—that Schoeberl, Dessler, and related 2024–2025 studies (including the APARC/WCRP assessment) underestimated the direct radiative forcing from the ~10% stratospheric water vapor increase and/or overestimated the compensating cooling from the co-injected aerosols.
Key reasons this remains plausible:Aerosol microphysics in models is acknowledged as challenging (e.g., the APARC report itself notes divergences in simulated growth rates, sedimentation, and decay), introducing substantial uncertainty in the negative forcing estimate (~-0.4 to -0.8 W/m² from aerosols).
Water vapor forcing calculations lean on the same core physics as older papers (Forster & Shine, Solomon et al.), which consistently yield positive ~0.2–0.4 W/m² for equivalent perturbations—yet recent works apply reductions or offsets without equivalent sensitivity testing for vapor dominance scenarios.
The eruption's plume was unusually high and water-rich with relatively low sulfur (compared to Pinatubo-class events), so extrapolating aerosol cooling efficacy from canonical volcanic cases may overestimate reflection.
The 10percent increase from Hunga Tunga may be underestimated, with some indications of a 15% global increase for a time.
Observational separation of signals remains difficult amid high interannual variability (El Niño, albedo shifts), allowing room for the net forcing to swing toward mild-to-moderate warming if aerosol effects decay faster or vapor persistence/latitude distribution amplifies greenhouse trapping more than modeled.
Critics (like myself, ha) argue this uncertainty was not symmetrically explored, with the burden placed heavily on proving vapor-driven warming rather than disproving it. Thus, a net positive forcing contribution to the 2023–2024 spike—potentially rivaling or exceeding El Niño/albedo factors—remains a legitimate alternative hypothesis within the bounds of established radiative physics.
It appears to me that Record-low planetary albedo (reduced low-level cloud cover over oceans may have overwhelmed or have been far more contributory to said warming then the less certain ad direct cleaner aerosols from IMO 2020 regulations) With 0.5–1 W/m² extra absorbed solar radiation. (again it is likely that human actions are over estimated)
Likely the El Nino, the record low planetary albedo, (low level cloud cover), which on a decadal scale was a large factor in the multi decadal warming trend, plus Hunga Tunga. all combined for the record warm surge, with Anthropogenic CO2 being a non factor.
Thanks David, I intend to explore a lot of what you have said here in two subsequent posts.
I appreciate your post... Thank you.
It’s been annoying but it doesn’t really matter that the establishment has dissembled and censored on Hunga Tonga from day one. Its unprecedented effects are slowly but surely dissipating as shown by the UAH global tropospheric temperature series: https://www.drroyspencer.com/wp-content/uploads/UAH_LT_1979_thru_December_2025_v6.1_20x9-scaled.jpg.
I look forward to the day, in maybe a few months, when they have to confront the inconvenient fact that global temperatures are back to where they were almost 30 years ago.
The climate change hoax is imploding in the face of unavoidable reality, with the helpful assistance of President Trump who has just withdrawn from the UN IPCC and the UN FCCC.