Little Girl, Big Impact: La Niña and Her Effects on South American Agriculture

Oscar Wilde once quipped that, “Conversation about weather is the last refuge of the unimaginative”. I imagine then, that Mr. Wilde would be sorely disappointed to learn that much of the discussion swirling around Latin American agriculture this year is focused on the La Niña phenomenon and its potential effects in the region.

Unimaginative or not, shifting weather patterns have a profound effect on agricultural production. By influencing precipitation and temperature, climatic dynamics have the potential to either hurt or help output. These impacts may manifest in yields, the area a farmer plants, the presence of pests, and many other factors.

This year we find ourselves squarely in a La Niña weather pattern. In this post we explore, what a La Niña is and what it means for regional agriculture.

Cooling Down

La Niña is the name assigned to one phase of the El Niño Southern Oscillation (ENSO). During the La Niña phase, strong trade winds off the Pacific coast of South America push warm surface water westward. Cooler water then wells up from the ocean’s depths. During a La Niña, the temperature at the ocean’s surface may be about 3 to 5 degrees Celsius lower than normal in the Equatorial Pacific. The National Oceanic Atmospheric Administration (NOAA) officially declares a La Niña in effect once the average surface temperature in a set area of the Pacific Ocean is less than 0.5 degrees Celsius below normal over a continuous period of several months.

La Niña is the inverse phenomenon of the perhaps better known El Niño phase. During an El Niño, weaker trade winds result in warmer than average sea surface temperatures in the Equatorial Pacific Ocean. If no major ocean surface temperature deviations are noted, a neutral phase is declared. Both La Niña and El Niño tend to occur every few years and last for several months before reverting back to a neutral weather pattern. La Niña events tend to last longer than the El Niño events.

The impacts of La Niña are excruciatingly nuanced, depending on the strength of the phase, the time of year the effect occurs and the specific geography in question. Broadly speaking, La Niña has a reputation for causing dry weather in South America, but this is a vast oversimplification. According to National Geographic, the La Niña effect does create high pressure systems over the Pacific Ocean which lead to reduced cloud formation, and thus reduced rainfall, most particularly along South America’s west coast and lowlands. However, this same weather system may also cause wetter than typical conditions along the southern rim of Brazil.

Generally, a La Niña system is considered to have a negative impact on agricultural production, and indeed some sectors do suffer from the climatic conditions created by the phenomenon. Probably most well-known is the negative impact of dry weather in the main corn and soybean producing areas of Argentina and Brazil. Farmer’s Business Network reports that during the last La Niña event, which occurred in 2017-2018 crop years, yields of corn and soybeans in Argentina were more than 20% lower than normal. Dry weather in the South American lowlands can also impact livestock and dairy production, many operations of which depend on high quality pasture to meet forage needs.

But not every sector is negatively impacted. For example, a La Niña can actually be highly beneficial to the fishing and aquaculture industries off the western coast of the continent. As deep ocean waters swell to the surface, they churn up organisms like plankton that can serve as food for other ocean critters.

La Niña in 2020

NOAA had been predicting the impending La Niña event this year for months. By August, the organization had issued a La Niña Watch, which was upgraded to a La Niña Advisory in September. A La Niña Advisory indicates that La Niña conditions are currently prevailing, namely that sea surface temperatures are colder than normal.

According to the most recent forecast emitted by NOAA, the La Niña phase is expected to remain dominant through the remainder of 2020, and at least through the first quarter of 2021. By the middle of next year, however, a neutral phase is expected to take over.

Concerns about moisture availability have been well voiced by crop and livestock producers this year. In Brazil, for example, a lack of rain pushed back soybean planting, leading to worries about the crop’s production for the year. Currently, about 23% of this year’s soybeans have been planted, while in a normal year about a third of soybeans should already be in the ground. Not only does this lag have implications for the soybean crop itself, but also for a second corn crop, known as the safrinha crop, which in Brazil is commonly planted immediately following the soybean harvest. A delayed soybean planting could thus prevent producers from planting their safrinha corn, or at least may diminish yields.

Suboptimal rainfall has had impacts in other parts of the continent as well. Dry weather has delayed the planting of the corn crop in Argentina by several percentage points. Meanwhile, livestock producers across the region have reported an increase in the need to feed their animals supplemental amouts of grain, which increases the farmers’ operating costs and decreases their profitability.

Agricultural stakeholders will be keenly observing climatic developments in the region, attempting to extrapolate the impacts of La Niña on production, yields, and prices this year and beyond. While we may not be able to change the weather, understanding climatic impacts like La Niña can inform strategies around agricultural operations. If producers, traders, and other folks along the agricultural value chain anticipate that the year will be dryer than normal, they can incorporate this knowledge to make production and financial decisions that can help them survive, and even thrive, in the prevailing environment.

Say what you will but conversations about weather being unimaginative? Not for agriculture!