<P> Future trends in ENSO are uncertain as different models make different predictions . It may be that the observed phenomenon of more frequent and stronger El Niño events occurs only in the initial phase of the global warming, and then (e.g., after the lower layers of the ocean get warmer, as well), El Niño will become weaker . It may also be that the stabilizing and destabilizing forces influencing the phenomenon will eventually compensate for each other . More research is needed to provide a better answer to that question . The ENSO is considered to be a potential tipping element in Earth's climate and, under the global warming, can enhance or alternate regional climate extreme events through a strengthened teleconnection . For example, an increase in the frequency and magnitude of El Niño events have triggered warmer than usual temperatures over the Indian Ocean, by modulating the Walker circulation . This has resulted in a rapid warming of the Indian Ocean, and consequently a weakening of the Asian Monsoon . </P> <P> Following the El Nino event in 1997--1998, the largest recorded to date, the Pacific Marine Environmental Laboratory attributes the first large - scale water bleaching event to the warming waters . This process results from warming ocean water temperatures . </P> <P> Based on modeled and observed Accumulated Cyclone Energy (ACE), El Niño years usually result in less active hurricane seasons in the Atlantic Ocean, but instead favor a shift of tropical cyclone activity in the Pacific Ocean, compared to La Niña years favoring above average hurricane development in the Atlantic and less so in the Pacific basin . </P> <P> The traditional ENSO (El Niño Southern Oscillation), also called Eastern Pacific (EP) ENSO, involves temperature anomalies in the eastern Pacific . However, in the 1990s and 2000s, nontraditional ENSO conditions were observed, in which the usual place of the temperature anomaly (Niño 1 and 2) is not affected, but an anomaly arises in the central Pacific (Niño 3.4). The phenomenon is called Central Pacific (CP) ENSO, "dateline" ENSO (because the anomaly arises near the dateline), or ENSO "Modoki" (Modoki is Japanese for "similar, but different"). There are flavors of ENSO additional to EP and CP types and some scientists argue that ENSO exists as a continuum often with hybrid types . </P>

One of the first indications that an el nio event may be occurring is when