Early action analysis for a potential La Niña in 2016 – 2017 / by Francisco Blaha

I wrote before about the impact of "El Niño" in fish distribution. This time, is the other way around, with early warning for a "La Niña".

FAO just produced a small report aiming to consolidate information on La Niña’s potential impacts on agriculture and food security, specifically in the regions which are now dealing
with the consequences of EL Niño, and to provide early action recommendations in the agriculture sector to either reap the beneficial outcomes of La Niña, or prevent, mitigate and prepare for its negative effects.

What is La Niña?
La Niña is the cooling of sea surface temperatures in the tropical Pacific, which occurs roughly every three to five years, lasting from six to 24 months. The chances of La Niña following an El Niño episode are higher on average — half of the El Niño events are followed by a La Niña — and typically it affects global climate patterns in the opposite way El Niño does. The intensity of the La Niña climatic phenomenon generally peaks between October and January.

What is the current forecast for La Niña?
Current forecasts indicate that there is a 55 to 70 percent chance of a La Niña episode developing towards the end of 2016, with a slightly lower chance that the onset may occur as early as July. The timing of a La Niña onset is key to determine how its consequences will impact on agriculture.

What are the main consequences of La Niña for agriculture and food security?
A La Niña phenomena generally affects the same regions that are impacted by El Niño, with opposite climatic consequences. Areas which experienced dry conditions (below-average rainfall and/or increased temperature) during El Niño, for instance, tend to receive above-average rainfall and in some cases cooler temperatures.

The diagram illustrates a potential timeline of La Niña-induced impacts across different regions based on the usual pattern observed during La Niña years.

The diagram illustrates a potential timeline of La Niña-induced impacts across different regions based on the usual pattern observed during La Niña years.

While the climatic phenomenon usually peaks in intensity between October and January, changes to climatic patterns and their related impacts on food security and agriculture can happen both before and after the peak. It’s possible that La Niña could develop as early as July, in which case it might already start affecting the growing seasons in some parts of the world from September 2016.

Consequences of La Niña on agriculture and food security can be both positive and negative. The positive effects derive from the increased likelihood of above average rainfall which could improve pasture and crop yields. At the same time, if the above-average rainfall results in flooding, then clearly the results may be negative as in this case there is an increased incidence of seeds being washed away, landslides, crops destroyed and livestock morbidity and mortality.

Since La Niña would most likely impact regions that have already been affected by El Niño, the food security situation could further deteriorate and protract into 2018. In the event of a “positive” La Niña, it is important to highlight that the actual full effect of an above average rainfall will not be felt until the next harvest — i.e. the end of 2016 (if La Niña comes early) or by mid-2017 (if La Niña occurs later).

Fisheries wise, the main effect could be the concentration of catches on the Westen side of the Pacific, in contrast to last years' "El Niño" when the fish was in the Central and East Pacific. (Hence my friends in the transhipment ports in PNG, RMI and FSM will have a busy season)

But consequences would vary widely across the Pacific. One of the main potential benefits would be the reduced likelihood of hurricanes in the northeast Pacific.

For a bigger picture of both "Niños" see this post from last year "Climate Change and Fisheries"