Summary of Maaneli (Max) Derakhshani: Does ENSO Dominate Global Warming? | Tom Nelson Pod #81

00:00:00 - 00:45:00

Maaneli Derakhshani, a theoretical physicist and postdoctoral researcher at Rutgers University, discusses the El Nino Southern oscillation (ENSO) and its impact on global warming. ENSO refers to two episodes: the warming El Nino and the cooling La Nina, which occur due to variations in air pressure patterns between Australia and Tahiti, leading to changes in ocean temperatures in Central and East Pacific Ocean. Derakhshani suggests that ENSO may have a dominant impact on global warming, citing changes in satellite temperature records and research reports that examine the correlation between ENSO and global temperature anomalies. He presents several lines of evidence that suggest that ENSO is a primary driving force behind global warming and argues that more research is needed to understand the natural climate variables that affect it. Derakhshani highlights the need to examine all evidence, even if it contradicts explanations of anthropogenic forcing.

• 00:00:00 In this section, Maaneli Derakhshani, a theoretical physicist and postdoctoral researcher at Rutgers University, explains the El Nino Southern oscillation (ENSO) and its relevance to global warming. ENSO is a coupled ocean-atmosphere phenomenon occurring across the tropical Pacific Ocean and refers to two main episodes: the warming episode called El Nino and the cooling episode called La Nina. These episodes occur due to variations in air pressure patterns between Darwin, Australia, and Tahiti, leading to changes in water surface temperatures in Central and East Pacific Ocean. Derakhshani suggests the possibility that ENSO may have a dominant impact on global warming as measured by satellite data and other temperature records.
• 00:05:00 In this section, Maaneli Derakhshani explains how the El Nino Southern Oscillation (ENSO) works to shuffle heat between the ocean and the atmosphere. During La Nina, colder water rises to the surface in the eastern half of the Pacific basin, creating a large region along the equator with below-normal surface temperatures, leading to heat from the atmosphere flowing into the ocean and resulting in global cooling. Conversely, during El Nino, warm waters in the west Pacific Ocean move eastward, creating a large region along the equator with above-normal ocean temperatures, leading to heat from the ocean going out into the atmosphere and resulting in global warming. Climate scientists consider ENSO as a form of internal climate variability that shuffles heat within the climate system, directly transferring heat from the ocean to the atmosphere and vice versa.
• 00:10:00 In this section, Max Derakhshani discusses the relationship between El Nino Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO), and global temperature variations. He highlights the multi-decadal cycles of ENSO where the tropical Pacific Basin favors El Nino for two or three decades, alternating with periods favoring La Nina. Derakhshani presents charts from a research report showing how the ENSO varies between La Nina and El Nino events and the Pacific shift, which led to global scale warming. He notes that from 1959 to 2015, there was a net warming due to these cycles, and the multivariate Enzo index takes into account temperature changes on the surface as well as in the air.
• 00:15:00 In this section, the speaker discusses various measures of Enzo phases, including the multivariate Enzo index, which is based on six observed variables in the tropical Pacific. He notes that while El Nino events globally lead to warming of air temperatures, La Nina events lead to cooling. The speaker presents a chart of the University of Alabama at Huntsville's satellite temperature record, which shows how global temperature anomalies have correlated with Enzo phases over time. He highlights how spikes and declines in temperature correspond with El Nino and La Nina events, suggesting that Enzo can explain some global warming and cooling periods, but not all.
• 00:20:00 In this section, the correlation between monthly variations in El Niño Southern Oscillation (ENSO) and temperature is discussed. While there are clear correlations between the two, there are also deviations that correspond to major volcanic events that cause cooling of the planet. Additionally, there is a lag of around six months between ENSO events and spikes and dips in temperature records. A paper from McLean and collaborators, published in the Journal of Geophysical Research in 2009, quantifies the extent of correlations between monthly variations in the Southern Oscillation Index (SOI) and both the UAH temperature record and the Rat Pack weather balloon temperature record. The paper shows that changes in SOI account for 72 percent of the variance in global tropospheric temperature anomalies.
• 00:25:00 In this section of the video, Maaneli (Max) Derakhshani discusses a study by McLean et al., which shows that the El Nino Southern oscillation (ENSO) has a dominant influence on global tropospheric temperature anomalies, particularly in the tropics, except for periods when equatorial volcanism causes ad hoc cooling. The study found that the SOI counts for 81% of the variance in tropospheric temperature anomalies in the tropics, which is expected since the ENSO phenomenon originates in the tropics. The study also shows that natural forcing mechanisms can account for most of the temperature variation over the last 50 years. The study's results are visually shown through a chart that compares University of Alabama at Huntsville satellite temperature record and changes in the southern oscillation index.
• 00:30:00 In this section, Dr. Maaneli Derakhshani explains how El Nino Southern Oscillation (ENSO) can affect global warming trends. He cites Dr. Roy Spencer's analysis of the UAH satellite temperature trend and the HadCRUT4 surface temperature trend, which shows that the trends change upon removing the El Nino event in 2015-2016. According to Dr. Spencer's analysis, the cumulative impact of ENSO can account for a substantial portion of temperature records, as much as over 90% in some cases. He also notes that this finding holds up over the complete record of some temperature datasets like UAH and RSS.
• 00:35:00 In this section, Maaneli Derakhshani discusses an endangerment finding report that addresses whether El Niño-Southern Oscillation (ENSO) dominates global warming. The report analyzes 13 different temperature time series and concludes that adjusting for ENSO, via three measures, accounts for all the warming trends in all 13 cases. Derakhshani presents two examples where adjusting for changes in Mei, which sums the magnitudes of the El Ninos and La Nina events, flattens the warming trends in temperature anomaly trend data sets for the lower troposphere satellite and global surface temperature anomalies.
• 00:40:00 In this section, Maaneli (Max) Derakhshani presents four lines of evidence that strongly suggest that Enzo, the El Nino Southern oscillation, is the dominant proximate driver of global warming trends in the atmosphere. He mentions that Enzo is influenced by other natural climate phenomena such as the Pacific decadal oscillation, planetary albedo, solar activity, and underwater volcanoes, which are not well understood and thus highly unpredictable. Derakhshani argues that more research is needed to understand Enzo and the natural climate variables that affect it, rather than just focusing on anthropogenic warming via greenhouse gases. Additionally, he mentions that scientists like Evan Schmidt and his colleagues use computer models that are simplified versions of the actual climate system and do not take into account the details of how Enzo occurs or how it relates to other natural climate phenomena. Derakhshani suggests that standard econometric modeling, which takes into account empirical data and non-linear relationships between different climate variables, may be a better approach for understanding global warming.
• 00:45:00 In this section, Maaneli Derakhshani discusses the literature surrounding the idea that the El Niño Southern Oscillation (ENSO) dominates global warming. He notes that papers from around 10 years ago suggest that ENSO accounts for global warming, but he is not aware of any recent literature examining this idea. He also encourages people to not be afraid to examine evidence that contradicts the explanation of anthropogenic forcing and to follow the evidence wherever it leads.