Pantropical Response to Global Warming and the Emergence of a La Niña‐Like Mean State Trend

Lee, Sang Ki; Kim, Dong-Min; Foltz, Gregory R.; Lopez, Hosmay

doi:10.1029/2019gl086497

Cited by 8 publications

(5 citation statements)

References 31 publications

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“…What kind of surface warming pattern will emerge in the equatorial Pacific in response to greenhouse gas forcing is still a subject of active debate 20,[23][24][25]27,39,[47][48][49][50][51][52] . Here we show that the projected warming pattern is strongly related to ENSO amplitude change once climate models are conditioned by their fidelity in dynamics responsible for ENSO asymmetry (as reflected in the simulated NDH efficiency).…”

Section: Resultsmentioning

confidence: 99%

Dynamics for El Niño-La Niña asymmetry constrain equatorial-Pacific warming pattern

2020

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The El Niño-Southern Oscillation (ENSO) results from the instability of and also modulates the strength of the tropical-Pacific cold tongue. While climate models reproduce observed ENSO amplitude relatively well, the majority still simulates its asymmetry between warm (El Niño) and cold (La Niña) phases very poorly. The causes of this major deficiency and consequences thereof are so far not well understood. Analysing both reanalyses and climate models, we here show that simulated ENSO asymmetry is largely proportional to subsurface nonlinear dynamical heating (NDH) along the equatorial Pacific thermocline. Most climate models suffer from too-weak NDH and too-weak linear dynamical ocean-atmosphere coupling. Nevertheless, a sizeable subset (about 1/3) having relatively realistic NDH shows that El Niño-likeness of the equatorial-Pacific warming pattern is linearly related to ENSO amplitude change in response to greenhouse warming. Therefore, better simulating the dynamics of ENSO asymmetry potentially reduces uncertainty in future projections.

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Section: Resultsmentioning

confidence: 99%

Dynamics for El Niño-La Niña asymmetry constrain equatorial-Pacific warming pattern

2020

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“…3a). In particular, faster warming in the tropical Indian and/or Atlantic oceans since 1980 has contributed to anomalous atmospheric sinking in the central tropical Pacific [89][90][91][92][93] . This sinking is conducive to enhanced equatorial easterly surface winds and, hence, to a cooling in the EP 90 .…”

Section: Internal Variabilitymentioning

confidence: 99%

Changing El Niño–Southern Oscillation in a warming climate

Cai

Santoso

Collins

et al. 2021

Nat Rev Earth Environ

351

207

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Originating in the equatorial Pacific, the El Niño-Southern Oscillation (ENSO) has highly consequential global impacts, motivating the need to understand its responses to anthropogenic warming. In this Review, we synthesize advances in observed and projected changes of multiple aspects of ENSO, including the processes behind such changes. As in previous syntheses, there is an inter-model consensus of an increase in future ENSO rainfall variability. Now, however, it is apparent that models that best capture key ENSO dynamics also tend to project an increase in future ENSO sea surface temperature variability and, thereby, ENSO magnitude under greenhouse warming, as well as an eastward shift and intensification of ENSO-related atmospheric teleconnections -the Pacific-North American and Pacific-South American patterns. Such projected changes are consistent with palaeoclimate evidence of stronger ENSO variability since the 1950s compared with past centuries. The increase in ENSO variability, though underpinned by increased equatorial Pacific upper-ocean stratification, is strongly influenced by internal variability, raising issues about its quantifiability and detectability. Yet, ongoing coordinated community efforts and computational advances are enabling long-simulation, large-ensemble experiments and high-resolution modelling, offering encouraging prospects for alleviating model biases, incorporating fundamental dynamical processes and reducing uncertainties in projections.

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“…Previous studies advised that the model mean state biases can partially contribute to the uncertainty of projected tropical Pacific SST change 37,38 . Further, with the deepening understanding of the pantropical climate interactions, the model's ability in capturing the trans-basin teleconnection tends to be essential for predicting the tropical Pacific future change 39,40 . Our present study emphasises the important role of simulated SST mean state in representing the Atlantic-Pacific connection, and provides additional insights into the projected Pacific mean state change under global warming.…”

Section: Discussionmentioning

confidence: 99%

Trans-basin Atlantic-Pacific connections further weakened by common model Pacific mean SST biases

Dommenget

McGregor

2020

Nat Commun

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A robust eastern Pacific surface temperature cooling trend was evident between ~1990–2013 that was considered as a pronounced contributor to the global surface warming slowdown. The majority of current climate models failed to reproduce this Pacific cooling trend, which is at least partly due to the underrepresentation of trans-basin teleconnections. Here, we investigate whether common Pacific mean sea surface temperature biases may further diminish the Atlantic-Pacific trans-basin induced Pacific cooling. Our results suggest that background Pacific SST biases act to weaken the trans-basin teleconnection by strengthening the Atlantic atmospheric stability and reducing Atlantic convection. These Pacific SST biases also act to substantially undermine the positive zonal wind-SST feedback. Furthermore, when combined, the Pacific and Atlantic SST biases led to Pacific cooling response that is almost non-existent (underestimated by 89%). Future efforts aim at reducing the model mean state biases may significantly help to improve the simulation skills of trans-basin teleconnections.

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Pantropical Response to Global Warming and the Emergence of a La Niña‐Like Mean State Trend

Cited by 8 publications

References 31 publications

Dynamics for El Niño-La Niña asymmetry constrain equatorial-Pacific warming pattern

Dynamics for El Niño-La Niña asymmetry constrain equatorial-Pacific warming pattern

Changing El Niño–Southern Oscillation in a warming climate

Trans-basin Atlantic-Pacific connections further weakened by common model Pacific mean SST biases

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