El Niño: The Not So Little Global Event

February 24, 2016

As ocean temperatures climb in the eastern Pacific Ocean along the equatorial coast of the Americas, a cascade of events begins to unfold.

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Higher than normal ocean temperatures are harming coral reefs around the world and causing massive bleaching. the strong 2015/2016 El Niño event taking place now, may continue to stress these vulnerable reefs for years to come.
© Dr. Richard Murphy, Ocean Futures Society

South American fisherman who first cited the periodically occurring warming seas and notable decreases in fish catches around the time of Christmas called the event, “El Niño,” meaning the “little boy” in reference to the birth of Jesus Christ. With the warming ocean waters comes a string of unusual events in the region, from heavy rains and massive flooding, to major reductions in local fish catches. One of the world’s largest fishery collapses occurred off the coast of Peru during the 1972 El Niño, devastating the Peruvian anchoveta fishery. While we often hear about the effects of El Niño close to home, there are numerous social and economic impacts that are felt around the word.

El Niño, formally referred to as the El Niño Southern Oscillation (ENSO), is a name given to naturally occurring cyclic events when sea surface temperatures in the Pacific Ocean become unusually warm from changes in atmospheric pressure, winds and ocean currents across the Pacific Ocean basin. However, over the last few years, ocean temperatures have been warming at unprecedented rates. Many scientists suggest that as global temperatures continue to rise from human accelerated climate change, El Niño events may intensify. This ocean-atmospheric process drives numerous extreme weather events affecting people, oceans and economies across the planet.

What El Niño Means for People

For those living in North America, El Niño is often described as bringing warm weather to the United States. The southern states receive mild winters, rain and storms with risks of major flooding and dangerous mudslides. In the west, winters are wet with heavy snowfall in the mountains and extreme surf along the coastlines. But less often discussed are the effects of El Niño in other places around the world. Is everywhere getting wetter and warmer? The answer is absolutely not.

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In the temperate ocean waters, where a variety of species of macroalgae thrive; the warmer waters associated with El Niño events are detrimental to their growth. Around some of the Channel Islands, off the Southern CA coast, the kelp forest has completely disappeared; but only temporarily as the kelp forests are extremely resilient and have been known to recovered quickly after past El Niño events. © Dr. Richard Murphy, Ocean Futures Society

While some places of the world experience more rain than normal, other places get very dry. During the 1997-1998 El Niño, which rivals this year’s event as the strongest on record, places of the world experienced widespread drought, severe outbreaks of disease, and thousands of deaths attributed to extreme weather. El Niño has been linked to food shortages and famine in many parts of the world due to its effects on prolonged droughts. In the 1997-98 El Niño, Papua New Guinea found itself in its most serious drought in 50 years, and many parts of southern Africa suffered major shortages in food production due to the lack of rains. In Indonesia, forest fires burned rampant from the lethal combination of human induced burning to clear forests and a lack of rain from El Niño. Because of the fires, regions of Southeast Asia experienced unprecedented smog and pollution levels, with inhabitants unable to go outdoors for days on end.

As this year’s strong El Niño unfolds, similar global trends are emerging. Indonesia is once again suffering enormous consequences from uncontrollable fires fueled by the dry conditions of El Niño. These fires are so immense that plumes of smoke can be seen from space, spewing greenhouse gas emissions into the atmosphere and adding to the growing effects of global climate change. So far, more than half a million people are sick with respiratory problems from smoke and particles in the air, and the economic losses have already reached $9 billion from damaged crops and disruptions in travel and tourism. Researchers have linked strong El Niño events to public health concerns due to the extreme variability in weather. While dry conditions spur droughts and fires that cause human harm, there are also risks from wetter-than-normal conditions, which can drive outbreaks of disease.

There is a wealth of information linking mosquito abundances to rainfall events. Mosquitos are a major concern because they can spread malaria, dengue fever and other devastating diseases. Following the major 1997-1998 El Niño, researchers found increases in dengue fever in many South Pacific Island Nations, as well as serious outbreaks of Rift Valley Fever in Kenya and Southern Somalia. Although numerous factors influence the prevalence of disease outbreaks, its clear that the associated changes in weather from strong El Niño events do indeed play an important role.


Humboldt squid are generally found in the warm Pacific waters off the Mexican coast but studies published in the early 2000s indicated an increase in northern migration. One of the reasons for the change in migration is suggested to be due to warming waters during El Niño events.
©Carrie Vonderhaar, Ocean Futures Society

What Happens to the Oceans?

When water temperatures get too high, some critical ocean species, such as corals, have a difficult time coping with the heat. Often, if water temperatures remain too warm, corals will expel their algae partners causing them to turn white in a process called coral bleaching. Sometimes corals can recover from this event, but not always. As coral reefs support the greatest diversity of fish on Earth, the health of corals is a major concern for fisheries and tourism industries around the planet.

Another major effect of El Niño in the oceans is the weakening of upwelling, which normally occurs along the western coast of the Americas. Upwelling brings deep nutrient-rich water to the surface, creating ideal conditions for plankton to flourish and form the foundation of the food web upon which all other animals depend. During El Niño, there is less upwelling, and therefore less naturally occurring plankton to nourish the breadth of marine life. However, artificial fertilizers used in agriculture often run off into the ocean. These nutrients may drive algae blooms, and certain algae produce toxins that when ingested by marine life, can be lethal. Scientists have discovered an association between El Niño events and increases in Ciguatera fish poisoning, which is an illness in humans caused by eating fish containing toxins produced by certain algae.

Diving in El Niño

Some people may wonder, with all these impacts of El Niño, is it safe to dive? Well, I would say yes! But be aware that you might be seeing a different ocean ecosystem than you would in normal years. Along the coast of California, it is likely that giant kelp forests, which can usually grow tens of meters, may be smaller and less productive in the warm waters during El Niño. On the other hand, you may witness creatures that wouldn’t normally be here. Recently, people have reported sea turtles, tunas, Humboldt squid, and hammerhead sharks, among other unusual warm water visitors to California’s normally cool waters. As these species follow the water temperature, they may find themselves as far north as Oregon and Washington, potentially competing with the fisheries industries up north.


Holly Lohuis, marine biologist with Jean-Michel Cousteau and his Ocean Futures Society team, safely dives with Humboldt squid. Ecologically the northern migration of this supreme predator is an important message of our changing seas. ©Carrie Vonderhaar, Ocean Futures Society

This year’s El Niño now sits at the top of the records alongside the 1997-1998 El Niño. During that year, 23,000 people lost their lives from the various effects of extreme weather and disease. The consequences of El Niño events affect many aspects of our lives, from public health, safety, and transportation to the economy of fisheries, tourism, and food security. As we continue to face the consequences of global climate change, we must think about how a warmer planet will affect us into the future. If warmer oceans contribute to stronger El Niños, we may face an entirely new era of weather extremes. On the other hand, the human species is a remarkable innovator and capable of adapting to the changing needs of the planet. We still have time to slow the effects of climate change and help the planet regain its balance, but we must do so together, and we must act now.

Warm regards,


Jean-Michel Cousteau
President, Ocean Futures Society
with Jaclyn Mandoske