A new El Niño looming – but how strong?

The El Niño Southern Oscillation (ENSO), which occurs roughly once in every 5-7 years, is the best known and by far the most dramatic, natural climate variability, said Dr Gary D. Sharp, an independent marine ecologist based at Salinas, California. “When ENSO occurs, tropical Pacific sea surface temperatures are warmer than normal (colder than normal periods are called La Niña). This warming of the ocean waters is followed by severe slowing of the equatorial easterly winds blowing over the western coast of South America that otherwise stimulate the equatorial upwelling of cooler, nutrient-rich water. When the real El Niño begins, the Humboldt Current, which brings cold waters from the Antarctic up the South American coast towards the equator weakens, and the temperatures rise considerably." Without the easterlies, the upwelling is replaced with an influx of the warm, less dense and nutrient-depleted surface water.

El Niño and fisheries

El Niño represents the most dramatic example of the dominance of climatic and oceanographic phenomena among factors that control the availability of fish resources to fishing. Thus, the effect of the looming El Niño on the mammoth anchoveta fishery depends on how it would weaken the upwelling along the coasts of Chile, Peru and Ecuador.

Previous ENSO events caused reduction of the catches of the Peruvian anchoveta from 13 to less than two million mt. On the other hand, with El Niño replaced by cool La Niña and the return of the easterlies, the former yields recuperated within a decade. (See this column, June 1997). The yields of anchoveta off the South West American coasts depend on the amounts and availability of both phytoplankton – the microscopic algae that serve as food for anchoveta larvae - and zoo plankton – macroscopic crustaceans and mollusks that, themselves a fodder of the anchoveta, feed on the algae. They also depend on the success of spawning, degree of predation by horse mackerel, bonito, and mackerel, which together with zillions of marine birds consume something in the order of the commercial catches, which are another influencing factor. The combination of all the above, and probably more factors, determines the degree of the availability and survival of anchoveta: its biomass may dwindle following larval and adult starvation, it may seek and migrate to areas where oceanic eddies enable them access to nutrient-rich sub-surface waters, it may disperse offshore in deep waters, etc. Lack of anchoveta due to El Niño may cause acute shortages on the world feed market and high prices of fishmeal, fish oil, and their vegetable substitutions (see this column, November 1998).

Off South West America, El Niños as a rule drive populations of sardine and mackerel northwards, and also push northward North West America’s salmon on its homecoming migration, and are followed with low Antarctic krill abundance. El Niño is killing coral reefs by generating the bleaching phenomenon. By some estimates, during the 1998 El Niño, in the South East Asian waters and in the Pacific Ocean, about 20 per cent of reefs died from bleaching.

Non-fishing effects

El Niño may affect much more than America's fisheries. If strong enough, it brings stormy weather over California and other US southern states, heavy rains in South American countries, and drought in South East Asia and Australia, Philippines, Indonesia, Southern Africa and Central America. According to the World Meteorological Organization (WMO), during past El Niño events, droughts lowered food production in many of those regions.

During the 1997-98 super El Niño, several thousand people were killed in floods, tornadoes and mudslides that caused billions of dollars of damage to crops, infrastructure and mines, worldwide. In Somalia, Ethiopia, Kenya, Sudan, Tanzania and Uganda floods killed more than 2,000 people.

On the other hand, a regular El Niño tends to moderate the Atlantic hurricane season and brings milder winters to North America, with fewer hurricanes in the Gulf of Mexico and more in the Eastern Pacific. A summer El Nino can lead to wetter than normal conditions in the inter-mountain regions of the United States and over central Chile.

New type of El Niño

While NOAA forecasters expect this El Niño to continue strengthening over the next few months and to last through the winter of 2009-2010, according to Professor Peter Webster of Georgia, USA, recent studies suggest that its nature may be changing, with not only a greater than average number of hurricanes, but also a greater chance of hurricanes making landfall. This new type of El Niño, known as El Niño Modoki (from the Japanese meaning "similar, but different"), forms in the Central rather than in the Eastern Pacific. It’s still to be seen how it’s going to affect the anchoveta and other fisheries.

Question marks

But, according to Mike Palmerino, US agricultural meteorologist with DTN Meteorlogix, at this time last year there were signs of an approaching El Niño, which evaporated towards the summer’s end. Also, according to the Australian weather bureau, while Pacific Ocean temperatures, cloud patterns and rainfall along the equator were now becoming consistent with a developing El Nino event, a major indicator of El Niño, the Southern Oscillation Index (SOI), was running contrary to a normal El Niño development being now positive 12, instead of negative (www.bom.gov.au/climate/enso/).

Also, according to independent WeatherAction Long Range Forecasters, "contrary to the claims of Global Warming and related models there will be no significant El Nino or associated warming effects in 2009".

Such ambiguous and even contradicting forecasts make it difficult to fishermen, processors, and farmers to plan their operations for the oncoming year. But this is how things are in our world’s ecosystem.