El Niño and our future climate: where do we stand?

El Nino and La Nina comprise the dominant mode of tropical climate variability: the El Nino and Southern Oscillation (ENSO) phenomenon. ENSO variations influence climate, ecosystems, and societies around the globe. It is, therefore, of great interest to understand the character of past and future ENSO variations. In this brief review, we explore our current understanding of these issues. The amplitude and character of ENSO have been observed to exhibit substantial variations on timescales of decades to centuries; many of these changes over the past millennium resemble those that arise from internally generated climate variations in an unforced climate model. ENSO activity and characteristics have been found to depend on the state of the tropical Pacific climate system, which is expected to change in the 21st century in response to changes in radiative forcing (including increased greenhouse gases) and internal climate variability. However, the extent and character of the response of ENSO to increased in greenhouse gases are still a topic of considerable research, and given the results published to date, we cannot yet rule out possibilities of an increase, decrease, or no change in ENSO activity arising from increases in CO2. Yet we are fairly confident that ENSO variations will continue to occur and influence global climate in the coming decades and centuries. Changes in continental climate, however, could alter the remote impacts of El Nino and La Nina. Copyright © 2010 John Wiley & Sons, Ltd. For further resources related to this article, please visit the WIREs website.

[1]  G. Vecchi,et al.  Increased tropical Atlantic wind shear in model projections of global warming , 2007 .

[2]  G. Vecchi,et al.  Global Warming and the Weakening of the Tropical Circulation , 2007 .

[3]  P. Xie,et al.  Global Precipitation: A 17-Year Monthly Analysis Based on Gauge Observations, Satellite Estimates, and Numerical Model Outputs , 1997 .

[4]  M. Scheffer,et al.  El Niño effects on the dynamics of terrestrial ecosystems. , 2001, Trends in ecology & evolution.

[5]  A. Timmermann,et al.  Increased El Niño frequency in a climate model forced by future greenhouse warming , 1999, Nature.

[6]  G. Vecchi,et al.  Weakening of tropical Pacific atmospheric circulation due to anthropogenic forcing , 2006, Nature.

[7]  A. J. Clarke,et al.  A Verified Estimation of the El Nino Index Nino-3.4 since 1877 , 2008 .

[8]  Lamont-Doherty Earth Observatory.  Anomalous ENSO Occurrences : An Alternate View * , 1997 .

[9]  A. Gnanadesikan,et al.  the Creative Commons Attribution 3.0 License. Ocean Science Regional impacts of ocean color on tropical Pacific variability , 2009 .

[10]  Wolfgang A. Müller,et al.  ENSO teleconnections in projections of future climate in ECHAM5/MPI-OM , 2008 .

[11]  A. Timmermann,et al.  Modeling evidence for enhanced El Nino-Southern Oscillation amplitude during the Last Glacial Maximum , 2004 .

[12]  F. Sirocko,et al.  El Niño variability off Peru during the last 20,000 years , 2005 .

[13]  M. Collins,et al.  El Niño in a changing climate: a multi-model study , 2005 .

[14]  Haijun Yang,et al.  ENSO amplitude change in observation and coupled models , 2008 .

[15]  Andrew T. Wittenberg,et al.  GFDL's CM2 Global Coupled Climate Models. Part III: Tropical Pacific Climate and ENSO , 2006 .

[16]  G. Vecchi,et al.  Examining the Tropical Pacific's Response to Global Warming , 2008 .

[17]  I. Kang,et al.  Successive Modulation of ENSO to the Future Greenhouse Warming , 2008 .

[18]  Matthew D. Collins,et al.  Coupled model simulations of mid-Holocene ENSO and comparisons with coral oxygen isotope records , 2006 .

[19]  B. Soden,et al.  Robust Responses of the Hydrological Cycle to Global Warming , 2006 .

[20]  Mechanisms controlling primary and new production in a global ecosystem model Part II: The role of the upper ocean short-term periodic and episodic mixing events , 2006 .

[21]  E. Rasmusson,et al.  Variations in Tropical Sea Surface Temperature and Surface Wind Fields Associated with the Southern Oscillation/El Niño , 1982 .

[22]  A. Leetmaa,et al.  Interactions between the Responses of North American Climate to El Niño–La Niña and to the Secular Warming Trend in the Indian–Western Pacific Oceans , 2008 .

[23]  Corinne Le Quéré,et al.  Climate Change 2013: The Physical Science Basis , 2013 .

[24]  Steven J. Worley,et al.  ICOADS release 2.1 data and products , 2005 .

[25]  D. E. Harrison,et al.  Global seasonal temperature and precipitation anomalies during El Niño autumn and winter , 2005 .

[26]  S. Vavrus,et al.  Rethinking Tropical Ocean Response to Global Warming: The Enhanced Equatorial Warming* , 2005 .

[27]  A. Fedorov,et al.  Is El Nino changing? , 2000, Science.

[28]  Stephen Cusack,et al.  Improved Surface Temperature Prediction for the Coming Decade from a Global Climate Model , 2007, Science.

[29]  L. Kornblueh,et al.  Advancing decadal-scale climate prediction in the North Atlantic sector , 2008, Nature.

[30]  G. Boer,et al.  Changes in Interannual Variability and Decadal Potential Predictability under Global Warming , 2009 .

[31]  T. Reichler,et al.  How Well Do Coupled Models Simulate Today's Climate? , 2008 .

[32]  G. Vecchi,et al.  Climate Response of the Equatorial Pacific to Global Warming , 2009 .

[33]  Warren M. Washington,et al.  El Niño-like climate change in a model with increased atmospheric CO2 concentrations , 1996, Nature.

[34]  W. Merryfield.  Changes to ENSO under CO2 Doubling in a Multimodel Ensemble , 2006 .

[35]  Jean-Michel André,et al.  Influence of the oceanic biology on the tropical Pacific climate in a coupled general circulation model , 2007 .

[36]  J. Chan.  Tropical Cyclone Activity over the Western North Pacific Associated with El Niño and La Niña Events , 2000 .

[37]  F. Chavez,et al.  Biological Consequences of El Ni�o , 1983, Science.

[38]  E. Guilyardi.  El Niño–mean state–seasonal cycle interactions in a multi-model ensemble , 2006 .

[39]  W. M. Gray,et al.  Atlantic Seasonal Hurricane Frequency. Part I: El Niño and 30 mb Quasi-Biennial Oscillation Influences , 1984 .

[40]  T. Knutson,et al.  Impact of CO2-Induced Warming on Simulated Hurricane Intensity and Precipitation: Sensitivity to the Choice of Climate Model and Convective Parameterization , 2004 .

[41]  A. Abe-Ouchi,et al.  A comparison of PMIP2 model simulations and the MARGO proxy reconstruction for tropical sea surface temperatures at last glacial maximum , 2009 .

[42]  M. Collins.  The El Niño–Southern Oscillation in the Second Hadley Centre Coupled Model and Its Response to Greenhouse Warming , 2000 .

[43]  William W. Hsieh,et al.  A Nonlinear Analysis of the ENSO Cycle and Its Interdecadal Changes , 2005 .

[44]  B. Kirtman,et al.  El Niño in a changing climate , 2009, Nature.

[45]  J. Overpeck,et al.  Unprecedented recent warming of surface temperatures in the eastern tropical Pacific Ocean , 2009 .

[46]  S. George Philander,et al.  Geophysical Interplays. (Book Reviews: El Nino, La Nina, and the Southern Oscillation.) , 1990 .

[47]  Thomas M. Smith,et al.  Improvements to NOAA’s Historical Merged Land–Ocean Surface Temperature Analysis (1880–2006) , 2008 .

[48]  Michael Botzet,et al.  Effects of Ocean Biology on the Penetrative Radiation in a Coupled Climate Model , 2006 .

[49]  A. Wittenberg,et al.  Spatial and temporal structure of Tropical Pacific interannual variability in 20th century coupled simulations , 2006 .

[50]  Gerald A. Meehl,et al.  Future changes of El Niño in two global coupled climate models , 2006 .

[51]  E. Cook,et al.  Variability in the El Niño-Southern Oscillation Through a Glacial-Interglacial Cycle , 2001, Science.

[52]  I. Smith,et al.  Weakening of the Walker Circulation and apparent dominance of El Niño both reach record levels, but has ENSO really changed? , 2007 .

[53]  R. Seager,et al.  Model Projections of an Imminent Transition to a More Arid Climate in Southwestern North America , 2007, Science.

[54]  D. E. Harrison,et al.  ENSO Warm (El Niño) and Cold (La Niña) Event Life Cycles: Ocean Surface Anomaly Patterns, Their Symmetries, Asymmetries, and Implications. , 2002 .

[55]  Upmanu Lall,et al.  Anomalous ENSO Occurrences: An Alternate View* , 1997 .

[56]  T. Delworth,et al.  Impact of Atlantic multidecadal oscillations on India/Sahel rainfall and Atlantic hurricanes , 2006 .

[57]  R. Seager,et al.  Orbital controls on the El Niño/Southern Oscillation and the tropical climate , 1999 .

[58]  A. Wittenberg.  Are historical records sufficient to constrain ENSO simulations? , 2009 .

[59]  Minghua Zhang,et al.  Evidence of deceleration of atmospheric vertical overturning circulation over the tropical Pacific , 2006 .

[60]  A. Navarra,et al.  Impact of extreme CO2 levels on tropical climate: a CGCM study , 2008 .

[61]  A. Broccoli,et al.  In Search of Paleo-ENSO , 2004, Science.

[62]  Timothy J. Hoar,et al.  The 1990–1995 El Niño‐Southern Oscillation Event: Longest on Record , 1996 .

[63]  M. Collins,et al.  El Niño- or La Niña-like climate change? , 2005 .

[64]  R. Seager,et al.  Observed Strengthening of the Zonal Sea Surface Temperature Gradient across the Equatorial Pacific Ocean , 2009 .

[65]  Kenneth R. Sperber,et al.  ENSO simulation in coupled ocean-atmosphere models: are the current models better? , 2006 .

[66]  G. Meehl,et al.  Multi-model changes in El Niño teleconnections over North America in a future warmer climate , 2007 .

[67]  G. Boer,et al.  Is there observational support for an El Niño‐like pattern of future global warming? , 2004 .

[68]  J. David Neelin,et al.  ENSO theory , 1998 .

[69]  D. Frierson,et al.  Response of the Zonal Mean Atmospheric Circulation to El Niño versus Global Warming , 2007 .

[70]  G. Burgers,et al.  The simplest ENSO recharge oscillator , 2005 .

[71]  S. Manabe,et al.  Time-Mean Response over the Tropical Pacific to Increased C02 in a Coupled Ocean-Atmosphere Model , 1995 .

[72]  Bin Wang,et al.  Why the properties of El Niño changed during the late 1970s , 2001 .

[73]  R. Lawrence Edwards,et al.  El Niño/Southern Oscillation and tropical Pacific climate during the last millennium , 2003, Nature.

[74]  E. Guilyardi,et al.  UNDERSTANDING EL NINO IN OCEAN-ATMOSPHERE GENERAL CIRCULATION MODELS : Progress and Challenges , 2008 .

[75]  A. Craig,et al.  Factors that affect the amplitude of El Nino in global coupled climate models , 2001 .

[76]  D. E. Harrison,et al.  Darwin sea level pressure, 1876–1996: Evidence for climate change? , 1997 .