Thongchai Thailand

Climate Change & ENSO

Posted on: November 29, 2019

FIGURE 1: EL NINO AND LA NINA CYCLES (ENSO): DATA PROVIDED BY JAN NULL, METEOROLOGIST, GOLDEN GATE WEATHER SERVICES, A RECOGNIZED SOURCE OF ENSO INFORMATION[LINK]elnino4

bandicam 2019-07-03 11-47-06-708

bandicam 2019-07-03 11-48-49-549

 

FIGURE 2: TREND ANALYSIS OF OCEANIC NINO INDEX 1950-2019oni-gifTREND-ANALYSIS-TABLE

 

FIGURE 3: CORRELATION BETWEEN ONI AND TEMPERATUREONITEMP-GIF

 

FIGURE 4: CORRELATION ANALYSIS: JJA-MAJJJAMAJ-1JJAMAJ-2

 

FIGURE 5: CORRELATION ANALYSIS NDJ-MAJNDJMAJ-1

NDJMAJ-2

 

FIGURE 6: THE GEOLOGICAL SOURCE OF ENSO EVENTSelnino-1

ELNINO2

[LINK TO THE HOME PAGE OF THIS SITE]

 

THIS POST IS A CRITICAL REVIEW OF THE CLAIM BY CLIMATE SCIENCE THAT AGW CLIMATE CHANGE HAS MADE THE EL NINO – LA NINA ENSO CYCLE MORE INTENSE.

  1. THE SOURCE STUDY BY GROTHE & COBB of the Georgia Institute of Technology’s School of Earth and Atmospheric Sciences: Grothe, Pamela R., et al. “Enhanced El Niño‐Southern Oscillation variability in recent decades.” Geophysical Research Letters, 2019}  Abstract: The El Niño‐Southern Oscillation (ENSO) represents the largest source of year‐to‐year global climate variability. While earth system models suggest a range of possible shifts in ENSO properties under continued greenhouse gas forcing, many centuries of pre-industrial climate data are required to detect a potential shift in the properties of recent ENSO extremes. Here, we reconstruct the strength of ENSO variations over the last 7,000 years with a new ensemble of fossil coral oxygen isotope records from the Line Islands, located in the central equatorial Pacific. The corals document a significant decrease in ENSO variance of ~20% from 3,000 to 5,000 years ago, coinciding with changes in spring/fall precessional insolation. We find that ENSO variability over the last five decades is ~25% stronger than during the preindustrial. Our results provide empirical support for recent climate model projections showing an intensification of ENSO extremes under greenhouse forcing. 
  2. The authors have kindly provided a translation of their scientific language into plain English as follows: Our climate models tell us that El Niño will intensify due to greenhouse warming. Here, new coral reconstructions of the El Niño‐Southern Oscillation (ENSO) record show sustained, significant changes in ENSO variability over the last 7,000yrs, and at the same time we have found ENSO extremes over the last 50 years that are stronger than ENSO cycles of pre-industrial times.These results tell us that El Niño events are intensifying due to anthropogenic climate change. Key Point: (1) Data from Line Island corals show ENSO strength significantly weaker between 3,000 and 5,000 years ago compared to the 2,000‐year ago. (2) ENSO extremes of the last 50 years are significantly stronger than those of the pre‐industrial era in the central tropical Pacific. (3) Therefore, AGW climate change is causing ENSO cycles to become more extreme.
  3. A further translation into plain language has been kindly provided by Sci-Tech-Daily online magazine [LINK] as follows: Compelling Hard Evidence: El Nino Swings More Violently in the Industrial Age: El Ninos have become more intense in the industrial age, which stands to worsen storms, drought, and coral bleaching in El Nino years. A new study has found compelling evidence in the Pacific Ocean that the stronger El Ninos are part of a climate pattern that is new and strange.It is the first known time that enough physical evidence spanning millennia has come together to allow researchers to say definitively that: El Ninos, La Ninas, and the climate phenomenon that drives them have become more extreme in the times of human-induced climate change. The industrial age ENSO swings are 25% stronger than in the pre-industrial records. The evidence had slumbered in and around shallow Pacific waters, where ENSO and El Ninos originate. The corals’ recordings of sea surface temperatures proved to be astonishingly accurate when bench-marked. Coral records from 1981 to 2015 matched sea surface temperatures measured via satellite in the same period exactly. In 2018, enough coral data had amassed to distinguish ENSO’s recent activity from its natural pre-industrial patterns. To stress-test the data, Grothe left out chunks to see if the industrial age ENSO signal still stuck out. She removed the record-setting 1997/1998 El Nino-La Nina and examined industrial age windows of time between 30 and 100 years long. The signal held in all windows, but the data needed the 97/98 event to be statistically significant. This could mean that changes in the ENSO activities have just now reached a threshold that makes the impact of the industrial economy detectable.

 

 

RESPONSE AND CRITICAL COMMENTS ON THESE REPORTS

  1. The ENSO data in the form of the Oceanic Nino Index (ONI) published by Jan Null [LINK]  is displayed in Figure 1. As of this writing, the data cover a 70-year time period from 1950 to 2019 and present the ONI data for a moving 3-month window. The period since 1950 {“mid century”} is claimed by NASA and also by climate scientists in general  to be one in which the theory of AGW in terms of CO2 forcing of surface temperature is most apparent [LINK] . Therefore, if there is an impact of AGW CO2 forcing of surface temperature on ENSO strength, it should be apparent in an analysis of the relevant trends and correlations with respect to the ONI (Oceanic Nino Index) and temperature.
  2. Trends in the 3-month running average of the Oceanic Nino Index are displayed graphically in Figure 2. The top frame of Figure 2 is a GIF animation that cycles through the ten 3-month moving average values of the ONI from June-July-Aug to April-May-June of the following year. The study period in these charts is 1950-2019. The red line through the data in these charts is a 3rd order polynomial regression line that should show the trends as well as changes if any in the trend midstream. These lines appear to be rather flat without any kind of trend information being apparent in the graphical representation.
  3. The bottom frame of Figure 2 presents the results of linear regression trend analysis of the ONI against time from 1950 to 2019. No evidence of a trend in the ONI is found in the data. This finding is inconsistent with the proposition that AGW climate change has caused an increase in El Nino strength. The mechanism of this change is assumed to be rising sea surface temperatures (SST) attributed to CO2 forcing of AGW climate change. A more direct analysis of this relationship is presented with correlation analysis presented in Figure 3, Figure 4, and Figure 5.
  4. The top frame of Figure 3 is a GIF animation that cycles through the six regions studied (global, northern hemisphere, southern hemisphere, northern extent, southern extent, and tropics. The graphic shows that the temperature above oceans in the tropics shows the strongest correlations. The somewhat weaker correlations found for the two hemispheres vanish when the tropical portion of the hemisphere is removed to define the northern and southern extents. The ordinate contains the ten three-month periods for which the mean ONI and temperature data are used in the correlation analysis. They are 1=June-July-August to 10=March-April-May.  The highest correlations are seen for the winter months along with late fall and early spring.
  5. Thus, we find that detrended correlation analysis shows a strong correlation between UAH lower troposphere temperature above ocean areas and ONI. The correlation supports a relationship between temperature and ONI. This correlation is strongest for temperatures above the tropics (TR). Statistically significant correlations are also seen for temperatures for the Northern and Southern Hemispheres (NH & SH) but these correlations disappear when the Tropical section of the hemisphere is removed in the hemispheric region being studied (NX & SX).
  6. These results suggest that there is a temperature phenomenon in the tropics that causes rising and falling ONI levels even in the absence of a trend. A rational explanation for this relationship is found in the geology of the tropical region near the Solomon Islands and Papua New Guinea as shown in Figure 6. A detailed description of this localized geological source of the energy that drives the ENSO variability is described in a related post [LINK] .
  7. We conclude from the results of the trend analysis and detrended correlation analysis presented above that the data do not support the hypothesis that AGW temperature trends since 1950 have caused ENSO intensity to increase. If that were so there would be a trend and that trend would show a strong correlation with temperature that is not restricted to the tropics. The Temperature trend above the tropics attributed to AGW for the ten 3-month means in the Jan Null analysis presented in Figure 7 below do not show an AGW forcing behavior. More importantly, the ONI does not show a rising trend. The data are consistent with the evaluation in a related post that ENSO variability is driven by geological forces rather than by atmospheric composition. 

 

FIGURE 7:  TROPICAL OCEAN TEMPERATURE AND ONI TRENDStemp-oni-trends

 

 

ENSO VARIABILITY BIBLIOGRAPHY

  1. Yeh, Sang-Wook, et al. “El Niño in a changing climate.” Nature 461.7263 (2009): 511.  El Niño events, characterized by anomalous warming in the eastern equatorial Pacific Ocean, have global climatic teleconnections and are the most dominant feature of cyclic climate variability on subdecadal timescales. Understanding changes in the frequency or characteristics of El Niño events in a changing climate is therefore of broad scientific and socioeconomic interest. Recent studies1,2,3,4,5 show that the canonical El Niño has become less frequent and that a different kind of El Niño has become more common during the late twentieth century, in which warm sea surface temperatures (SSTs) in the central Pacific are flanked on the east and west by cooler SSTs. This type of El Niño, termed the central Pacific El Niño (CP-El Niño; also termed the dateline El Niño2, El Niño Modoki3 or warm pool El Niño5), differs from the canonical eastern Pacific El Niño (EP-El Niño) in both the location of maximum SST anomalies and tropical–midlatitude teleconnections. Here we show changes in the ratio of CP-El Niño to EP-El Niño under projected global warming scenarios from the Coupled Model Intercomparison Project phase 3 multi-model data set6. Using calculations based on historical El Niño indices, we find that projections of anthropogenic climate change are associated with an increased frequency of the CP-El Niño compared to the EP-El Niño. When restricted to the six climate models with the best representation of the twentieth-century ratio of CP-El Niño to EP-El Niño, the occurrence ratio of CP-El Niño/EP-El Niño is projected to increase as much as five times under global warming. The change is related to a flattening of the thermocline in the equatorial Pacific.
  2. Timmermann, Axel, et al. “El Niño–southern oscillation complexity.” Nature 559.7715 (2018): 535-545.  El Niño events are characterized by surface warming of the tropical Pacific Ocean and weakening of equatorial trade winds that occur every few years. Such conditions are accompanied by changes in atmospheric and oceanic circulation, affecting global climate, marine and terrestrial ecosystems, fisheries and human activities. The alternation of warm El Niño and cold La Niña conditions, referred to as the El Niño–Southern Oscillation (ENSO), represents the strongest year-to-year fluctuation of the global climate system. Here we provide a synopsis of our current understanding of the spatio-temporal complexity of this important climate mode and its influence on the Earth system.
  3. Grothe, Pamela R., et al. “Enhanced El Niño‐Southern Oscillation variability in recent decades.” Geophysical Research Letters (2019).  The El Niño‐Southern Oscillation (ENSO) represents the largest source of year‐to‐year global climate variability. While earth system models suggest a range of possible shifts in ENSO properties under continued greenhouse gas forcing, many centuries of preindustrial climate data are required to detect a potential shift in the properties of recent ENSO extremes. Here, we reconstruct the strength of ENSO variations over the last 7,000 years with a new ensemble of fossil coral oxygen isotope records from the Line Islands, located in the central equatorial Pacific. The corals document a significant decrease in ENSO variance of ~20% from 3,000 to 5,000 years ago, coinciding with changes in spring/fall precessional insolation. We find that ENSO variability over the last five decades is ~25% stronger than during the preindustrial. Our results provide empirical support for recent climate model projections showing an intensification of ENSO extremes under greenhouse forcing.

 

 

3 Responses to "Climate Change & ENSO"

Thank you for these emails. It reassures me that intelligent thought does exist.

SR

On Thu, Nov 28, 2019 at 11:53 PM Thongchai Thailand wrote:

> chaamjamal posted: “FIGURE 1: EL NINO AND LA NINA CYCLES (ENSO): DATA > PROVIDED BY JAN NULL, METEOROLOGIST, GOLDEN GATE WEATHER SERVICES, A > RECOGNIZED SOURCE OF ENSO INFORMATION[LINK] FIGURE 2: TREND ANALYSIS OF > OCEANIC NINO INDEX 1950-2019 FIGURE 3: CORRELA” >

Thank you, Joggingpop

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