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Showing posts with the label cloud feedback

Can Changes in Cloud Cover Drive Global Warming?

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Ned Nikolov and Karl Zeller have published a new paper (NZ24) in the quasi-predatory MDPI journal geomatics [1] which claims to rule out the effects of greenhouse gases as a cause for the increase in GMST in recent decades. Their paper concludes, Our analysis revealed that the observed decrease of planetary albedo along with reported variations of the Total Solar Irradiance (TSI) explain 100% of the global warming trend and 83% of the GSAT interannual variability as documented by six satellite- and ground-based monitoring systems over the past 24 years. Changes in Earth’s cloud albedo emerged as the dominant driver of GSAT, while TSI only played a marginal role. They produce a graph that they believe supports their claim, which sure enough shows a decrease in the Earth's albedo over the last 24 years and a corresponding increase in absorbed solar radiation (ASR). Let me be clear here at the beginning that there absolutely has been both a decrease in albedo and a corresponding in c...

Quantifying Cloud Feedbacks for Climate Sensitivity

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One of the more challenging aspects of climate science today is quantifying the cloud feedbacks to better constrain estimates for equilibrium climate sensitivity (ECS). It’s long been understood that low clouds generally have a cooling influence, while higher clouds increase warming via the greenhouse effect. Previous attempts at quantifying the net feedback have produced results where the confidence interval is larger than the estimate. For instance, Andrew Dessler’s estimates[1][2] were +0.50 ± 0.75 W/m^2/K over a 10 year period. Zhou’s estimate[3] was −0.16 ±0.83 W/m^2/K. Attempts at simulating clouds in some of the CMIP6 models have produced ECS values that are likely too high,[4] though many of these issues have since been largely resolved.[5][6][7]. A new study,[8] however, has succeeded at quantifying these cloud feedbacks at 0.43 ± 0.35 W/m^2/K. This means that for every 1 C warming, we can expect an additional 0.43 W/m^2, amplifying warming. Given these results, there is just...