Summary of Maaneli (Max) Derakhshani: ENSO Warming vs CO2 Warming | Tom Nelson Pod #89

00:00:00 - 00:35:00

Maaneli Derakhshani, a theoretical physicist and postdoctoral researcher at Rutgers University, compares Enzo warming to CO2 greenhouse warming and presents evidence for the dominance of Enzo warming in the past half-century. He argues that the direct warming from CO2 is too small to account for the observed warming and that the IPCC assumes net positive feedbacks from water vapor and clouds to amplify warming from CO2 using computer models, but clouds remain the largest contribution to overall uncertainty in climate feedbacks and climate models. Derakhshani points out that not a single one of the CMIP6 climate models matches the observational record of the temperature trend estimates in the tropics, and the models predict far too much warming on average globally and in the tropics compared to tropospheric observations by multiple data sets and multiple methods, suggesting that negative feedbacks from water vapor and clouds must be significantly underestimated by models.

• 00:00:00 In this section, Maaneli Derakhshani, a theoretical physicist and postdoctoral researcher at Rutgers University, compares Enzo warming to CO2 greenhouse warming. He aims to address questions regarding the relative magnitude of both types of warming and how CO2 warming may impact Enzo warming. Derakhshani presented evidence for the dominance of Enzo warming in the past half-century, including clear visual correlations between El Nino events, Enzo index variations and changes in temperature anomalies. He also showed a correlation between the southern oscillation index and temperature anomalies measured by UAH satellites. Derakhshani then poses questions about the comparison between Enzo and CO2 warming and aims to answer them in the rest of the presentation.
• 00:05:00 In this section, Dr. Max Derakhshani discusses the analysis of global warming in the 21st century and how El Niño events impact temperature anomalies. He presents a report from Wallace and Christy that finds adjusting temperature time series only for the impacts of the El Niño Southern Oscillation (ENSO) is sufficient to account for all of the temperature trends in different time series. In terms of CO2 warming, he highlights a review paper by Happer and van Wijngaarden that shows that a doubling of atmospheric CO2 reduces the thermal radiation flux to space by about one percent, resulting in a radiative forcing of about three watts per square meter and a quarter of a percent increase in the surface absolute temperature, which corresponds to a temperature increase of 0.75 Celsius - a very small effect.
• 00:10:00 In this section, Dr. Maaneli Derakhshani explains that a doubling of atmospheric CO2 concentration to 560 PPM would only increase the absolute surface temperature by about 0.75 Celsius, and that the warming effect of CO2 is logarithmic and requires a doubling in concentration for each subsequent increase in temperature. He argues that the direct warming from CO2 is too small to account for the observed warming recorded by satellite records, and that the IPCC assumes net positive feedbacks from water vapor and clouds to amplify warming from CO2, which they simulate using climate computer models. The models assume that the direct warming from CO2 results in more evaporation of water, which in turn increases greenhouse warming from the more abundant and powerful greenhouse gas, water vapor.
• 00:15:00 In this section, the speaker discusses the water vapor feedback mechanism and its uncertainties due to the inclusion of clouds as a variable in the climate system. While the Clausius Leperon relation is well established in laboratory experiments, it is unclear if it holds true for the climate system as clouds produce a significant negative feedback to CO2 warming. Moreover, upper-level thin cirrus clouds produce a positive feedback to warming, but the Iris effect identified by Richard Linson and his collaborators shows that a reduction in such cloud coverage implies a negative feedback as more heat can escape to space. The IPCC's AR-6 report concedes that clouds remain the largest contribution to overall uncertainty in climate feedbacks and climate models, and there is a great deal of uncertainty as to whether net feedbacks from clouds and water vapor could be significantly negative and cancel out most or all of the warming from CO2.
• 00:20:00 In this section, Maaneli Derakhshani discusses the uncertainty associated with climate models and the difficulty in accurately inferring that a rise in global average temperature is due to greenhouse gas forcing rather than changes in cloud coverage and feedbacks. Despite this uncertainty, there are specific predictions that can be made, such as the hot spot in the tropics, which is a well-established prediction that there will be a region of the atmosphere that is much warmer than at other latitudes of the planet. Derakhshani presents a pair of charts from John Christie showing that not a single one of the CMIP6 climate models matches the observational record of the temperature trend estimates for 1979 to 2020 in the tropics.
• 00:25:00 In this section, Maaneli Derakhshani discusses the discrepancies between ENSO and CO2 warming models, using charts and data to illustrate the differences in observations and predictions. He points out that the cmip6 models predict far too much warming on average globally and in the tropics compared to tropospheric observations by multiple data sets and multiple methods, suggesting that negative feedbacks from water vapor and clouds must be significantly underestimated by models. He also discusses how Enzo modeling compares to the CO2 cmip6 or cmip5 models or temperature variations in the tropics, showcasing a chart from McLean and collaborators' paper that compares the derivatives of the Southern oscillation index to the UAH tropospheric temperature anomalies.
• 00:30:00 In this section, the speaker discusses the relationship between the Southern Oscillation Index (SOI) and temperature anomalies in the tropics. He states that temperature anomalies from satellite data show a strong correlation with the SOI derivative by 81% in the tropics, suggesting that Enzo warming can account for the variability in the temperature anomaly data set. The speaker also suggests that the MEI-based regression model fits the data extremely well and avoids the need to model feedback from water vapor and clouds, which he believes renders climate computer models useless. Finally, the speaker argues that direct CO2 warming cannot account for multi-decadal changes in the magnitude and frequency of El Ninos and La Ninas, and that there is no consensus among models about whether El Ninos would increase or decrease in magnitude or frequency in the future due to amplified CO2 warming.
• 00:35:00 In this section, Maaneli (Max) Derakhshani argues that the predictions for Enso (El Nino Southern Oscillation) cannot be considered reliable since cmip6 and cmip5 models significantly overpredict warming compared to observational data. He suggests that the warming from Enso and CO2 are effectively independent of one another and that their total contributions are additive. He concludes that Amplified CO2 warming plays a very minor role in global warming, and the net feedbacks to it can be inferred to be either zero or negative, whereas Enso warming plus CO2 warming with net zero or net negative feedback seems like a viable possibility compatible with observations.