ENSO response to greenhouse forcing

Cai, Wenju and Santoso, Agus and Wang, Guojian and Wu, Lixin and Collins, Mat and Lengaigne, Matthieu and Power, Scott and Timmermann, Axel (2021) ENSO response to greenhouse forcing. In: El Nino Southern Oscillation in a changing climate. Geophysical Monograph Series (253). John Wiley & Sons, Inc., United States, pp. 289-307. ISBN 9781119548126


Abstract

How ENSO responds to an increasing concentration of greenhouse gases in the atmosphere has remained an elusive issue for decades. Climate models produce widely diverging results based on the traditional sea surface temperature (SST) metrics of ENSO. Some models project stronger ENSO SST variability, some weaker, some show no clear change. Steering away from these static measures, but more carefully examining the underlying processes and the associated key physical characteristics of ENSO, a clearer picture begins to emerge. Due to the nonlinear response of the atmosphere to SSTs, climate models project an increase in ENSO-driven precipitation. Such a response tends to be robust across models linked to the relatively strong intermodel agreement in projected changes of the Pacific mean climate, marked by equatorially enhanced warming and weakened Walker Circulation. These mean-state changes facilitate increased frequency of extreme El Nino events in models that are able to simulate nonlinear properties of ENSO closer to observations. In this ensemble of selected models, the frequency of extreme La Nina events is also projected to increase, as facilitated by faster warming of the Maritime Continent than the surrounding ocean waters. A projected increase in upper-ocean stratification further favors increased variability and occurrences of Eastern Pacific El Nino. Uncertainties, however, remain due to persistent model biases, highlighting the need to further improve climate models, as well as sustain reliable observations to constrain model projections. Nonetheless, these projections underscore a possible heightened impact of ENSO-driven changes in a warming climate.


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Item Type: Book Chapter (Commonwealth Reporting Category B)
Refereed: Yes
Item Status: Live Archive
Additional Information: Permanent restricted access to Published chapter + Front Matter, in accordance with the copyright policy of the publisher.
Faculty/School / Institute/Centre: No Faculty
Faculty/School / Institute/Centre: No Faculty
Date Deposited: 11 Oct 2021 02:18
Last Modified: 13 Oct 2021 05:34
Uncontrolled Keywords: ENSO; greenhouse gases
Fields of Research (2008): 04 Earth Sciences > 0401 Atmospheric Sciences > 040104 Climate Change Processes
Fields of Research (2020): 37 EARTH SCIENCES > 3702 Climate change science > 370201 Climate change processes
Socio-Economic Objectives (2008): D Environment > 96 Environment > 9603 Climate and Climate Change > 960309 Effects of Climate Change and Variability on the South Pacific (excl. Australia and New Zealand) (excl. Social Impacts)
Socio-Economic Objectives (2020): 19 ENVIRONMENTAL POLICY, CLIMATE CHANGE AND NATURAL HAZARDS > 1905 Understanding climate change > 190502 Climate variability (excl. social impacts)
Identification Number or DOI: https://doi.org/10.1002/9781119548164.ch13
URI: http://eprints.usq.edu.au/id/eprint/42375

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