How Will Global Warming Affect El Niño in the 21st Century? – The Weather Channel
El Niño remains the largest climate phenomenon that occurs frequently producing droughts, floods, wildfires, dust and snow storms, fish kill, and even elevated risks of civil conflicts. The theater of action for El Niño is the tropical Pacific Ocean but its global reach costs the global community tens of billion dollars each time.
El Niño’s occur every two-to-seven years with very strong El Niño’s occurring about every 15 years. How its frequency or the time between two events and strength will change because of global warming remains a grand challenge for climate models. This also impacts projections of future climate since El Niños redistribute the heat gathered by the ocean between two El Niño events to cause a mini global warming. The most recent projection of global warming impact on El Niño appeared in scientific journal Nature in December 2018.
El Niño is measured by an index that averages sea surface temperature anomalies over the central-eastern tropical Pacific. Each model delivers a slightly different rendition of El Niño compared to nature. This has been an issue in finding a consensus among models as far as the El Niño response to global warming is concerned. But by using a model-specific El Niño index to make room for the inter-model differences, the latest projection posits that strong El Niño’s and thus extreme weather events associated with such strong El Niño’s will increase in the coming decades.
The results should serve as a warning to the countries on all continents that suffer from these extreme weather events during strong El Niño events such as the ones during 1982-83, 1997-98 and 2015-16. However, some major caveats are in order.
The first caveat is that the eagerly-awaited winter rain and snow storms over California did not occur over California during the latest extreme El Niño. It is thus unclear if global warming is already affecting El Niño and its remote impacts. Secondly, the models used for making future projections have not stood the test of time for their depiction of El Niño during the 20th century.
The mean state of the tropical Pacific has cold temperatures in the east around the Galápagos Islands because the trade winds blowing from the east to west diverge waters away from the equator and push them westward. The atmosphere warms westward, moving waters and piling it in the west. Warm waters favour atmospheric convection and produce over 5 meters of rain per year to the west of the Dateline to New Guinea. El Niño is a perturbation of this background state of cold east – warm west ocean with air rising in the west and sinking in the east.
This story was originally published by India Science Wire
The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.