Tail wagging the dog: Changes in ENSO Activity During the Last 6,000 Years Modulated by Background Climate State

This paper claims that ENSO is a following rather than a forcing of climate, but given what we’ve seen in the last two decades, it sure seems like ENSO El Nino events are in fact a forcing of the global climate, from which the Earth quickly recovers.

WUWT graphic by Anthony Watts

The paper: (paywalled)

Changes in ENSO Activity During the Last 6,000 Years Modulated by Background Climate State
Soon‐Il An, Seul‐Hee Im, Sang‐Yoon Jun

Abstract
Various proxy records show that El Niño–Southern Oscillation (ENSO) activity has changed from calm to active during the last 6,000 years. However, it is so far unclear whether orbital forcing has solely induced such a dramatic change. In this study, we performed a transient run for the last 6,000 years using an Earth system model of intermediate complexity affected by orbital forcing only without changes due to other climate forcing, and then its time‐varying background states were implemented into an intermediate atmosphere‐ocean coupled model for ENSO. ENSO activity simulated by the intermediate atmosphere‐ocean coupled model during the last 6,000 years resembled the observed proxy data, inferring that orbital forcing mainly leads to changes in ENSO activity during the last 6,000 years. From additional sensitivity experiments, we found that a change in sea surface temperature background conditions is primarily responsible for the observed ENSO activity over the last 6,000 years through modifying the anomalous horizontal thermal advection of the mean SST gradient.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2017GL076250

UPDATE BY ANTHONY: Commenter “frankclimate” has provided a URL for the paper:

https://www.docdroid.net/QmS34GN/101002-at-2017gl076250.pdf

Reading it, it all makes sense now, thanks to that mighty big word “may”:

[Update by Willis Eschenbach]

I trust that Anthony won’t mind my noting that I’ve said for some time that the El Nino/La Nina pump is indeed a “following rather than a forcing of climate”, to use Anthony’s words. To be more precise, it is another temperature-regulating emergent phenomenon, one which occurs when the Pacific ocean temperature and surface heat content get above a certain level. At that point, the winds spring up and push millions of cubic metres of warm ocean water towards the poles, cooling the ocean.

The Tao of El Nino 2013-01-28

I was wandering through the graphics section of the TAO buoy data this evening. I noted that they have an outstanding animation of the most recent sixty months of tropical sea temperatures and surface heights. Go to their graphics page, click on “Animation”. Then click on “Animate”. When the new…

The Power Stroke 2014-02-27

I got to thinking about the well-known correlation of El Ninos and global temperature. I knew that the Pacific temperatures lead the global temperatures, and the tropics lead the Pacific, but I’d never looked at the actual physical…

Ref.: https://wattsupwiththat.com/2018/05/13/tail-wagging-the-dog-changes-in-enso-activity-during-the-last-6000-years-modulated-by-background-climate-state/

………

Climate is all internal response – effect. Internal cycling of energy. All climate, weather phenomenon, are cooling processes. El Niño is a “fast” cooling process (there’s more energy being transported out of the atmosphere), La Nina is a “slower” cooling process (there’s less energy transfer, or loss).

You could say El Niño is a forcing of climate, if a faster, stronger (more) transfer of energy is a forcing phenomenon.