The 2013-2022 warming trend and the extreme warmth in 2023 were “not associated with” declining outgoing long-wave radiation induced by rising greenhouse gases. [emphasis, links added]
Instead, a new study published in the journal Science contends that decreasing cloud albedo and the consequent increase in ASR, or absorbed solar radiation (+0.97 to 1.10 W/m²/decade according to ERA5 and CERES, respectively) explains the warming over the last decade. (Less cloud cover means more solar radiation reaches the Earth’s surface, warming it.)
A rising trend in anthropogenic greenhouse gases was supposed to reduce the Earth’s outgoing long-wave radiation (OLR), and a declining OLR was thought to be the driver of modern warming.
Instead, the opposite has occurred. There has been an increasing OLR trend since 2013.
This enhancement of the Earth’s OLR trend actually serves to counteract the ASR-induced warming strongly associated with the aforementioned declining cloud cover albedo.
In other words, the total greenhouse effect impact from rising greenhouse gases has recently been contributing to a reduction in global warming, partially offsetting the warming induced by rising ASR.
“The EEI trend and 2023 peak are not associated with decreasing outgoing longwave radiation (OLR), as one would expect from increasing greenhouse-gas concentrations in the absence of shortwave feedbacks. Instead, OLR has been increasing and largely offsetting even stronger absorbed solar radiation (ASR) anomalies, consistent with climate models.
“The decadal 2013–2022 trend in ASR amounts to +1.10 W/m²/dec−1 in CERES and +0.97 W/m²/dec−1 in ERA5, reaching astonishing anomalies of +1.82 W/m² in CERES and +1.31 W/m² in ERA5 in 2023. Variations of incident solar radiation (ISR), including by the 11-year solar cycle, are an order of magnitude smaller, implying that reduced planetary albedo is the dominant cause.
“It is however striking that, according to CERES, ISR attained a positive anomaly in 2023 of +0.28 W/m², well above the previous solar-cycle maximum, whereas ERA5 forcing still assumed a negative anomaly of -0.08 W/m².”
Read more at No Tricks Zone
