Climate Update: La Niña Weakening

Recently, the Australian Bureau of Meteorology published an article stating that ocean temperature fluctuations indicate La Niña conditions experienced over the past few months may be weakening. As La Niña typically creates greater hurricane activity in the Atlantic Ocean and higher risk of drought in the southern portions of the United States, this should be welcome news to the U.S. agricultural industry. Meteorologists, however, might have a different opinion on weather patterns over the next few months.

In the food commodity business, we are fundamentally connected to the weather and its influence on the supply of grains, sugar, and fruit. Let’s take a closer look at this weather phenomenon.

Sibling rivalry

Many people get confused between El Niño and La Niña. “Which is the one that causes rain/drought?” is a common question we hear. El Niño and La Niña are extremes of the same cycle, the El Niño Southern Oscillation (ENSO). ENSO is irregular in that it doesn’t occur on a set schedule, but its weather pattern shift is continual in that it is an ongoing aspect of the tropical Pacific Ocean’s current cycle. Here is a summary of the most common climate changes during El Niño and La Niña:

Normal trade winds push the warm air of the tropical Pacific west, toward Indonesia, carrying rain with them, thus providing the monsoon season on which this region of the world depends. When El Niño occurs, the trade winds are weakened and the flow of warm air and water flows east, toward Peru and the west coast of North America—which is why El Niño is also called a warm event. The rain that usually soaks the jungles of Indonesia now soaks these normally dryer regions. Peru can experience devastating floods during very strong El Niño events; Australia can suffer from drought.

La Niña—also called a cold event—occurs when the trade winds intensify; subsequent wave action seems to pull up cooler water and lower the surface temperature of the equatorial Pacific. La Niña frequently, but not always, follows an El Niño event as part of the oscillation cycle.

Recent El Niños occurred during 1982/83, 1986/87, 1991–1994, 1997/98, and 2006/07. Recent La Niñas occurred during 1988/89, 1995/96, 1998–2001, and 2007/08. Climatologists note that ENSO has cycled more frequently over that last 25 years than previously.

How ENSO affects crop production depends on where the crop is located. In Australia, for example, El Niños bring drought and a consequent plunge in wheat production. In the United States, ENSO’s effect on grain production is less clear. We cannot say that because we are experiencing El Niño conditions or La Niña conditions, that the Plains and Midwest are then going to have a drought. What we do know is that extreme weather (droughts and floods) in the interior U.S. does seem to coincide with the extremes of ENSO (see chart).

Drought is the major force that affects a grain crop’s productivity, and as El Niño and La Niña have been more prevalent over the past 25 years, we can see how crop productivity fluctuates given dry conditions. No one weather phenomenon bears the blame for drops in crop production. But knowing what climate trends may occur can help farmers strategize to lessen damage.

Predicting ENSO fluctuations

Thanks to sophisticated software and satellite imaging, we have made huge strides over the last ten years in understanding and predicting ENSO. Meteorologists and oceanographers are working together to monitor the data from satellites and a system of fixed mid-ocean buoys in the Pacific.

NOAA now knows that La Niña years tend to have active Atlantic hurricane seasons. The wind patterns over the Atlantic during La Niña seem to be more conducive to storm formation. Early detection of a La Niña can allow the Gulf states a head start in preparing their populations for possible increased hurricane activity.

We have seen that in hurricane-vulnerable states, crops suffer twice: first from immediate storm damage, such as wind-damaged fruit trees and flooded soybean and sugarcane fields. And then crops often suffer from pests and diseases that the winds carry from one region to another, which can be even more destructive than the storms themselves. Florida was hit hard by this double whammy over the last few years, as crop size has greatly diminished and groves continue to suffer from canker, greening, and pests. With a more thorough knowledge of La Nina’s effect on hurricanes, growers in the Gulf states can track which new pests and diseases may be blown their way and implement monitoring systems to detect them as soon as possible.

The months ahead

As for this year, scientists conjecture that La Niña conditions we have experienced since mid-2007 could be neutralizing. Given that we know La Niña conditions are more conducive to Atlantic hurricane activity, it is puzzling that researchers at Colorado State University have said with a fair amount of certainty that activity will increase this coming season, despite the neutralizing conditions. After having incorrectly predicted increased activity last season, meteorologists at the university assert they have refined their research methods for testing water temperatures—a key indicator—and that this year’s findings will prove much more accurate.

As always, weather predictions large and small should be taken with a grain of salt, particularly when overall meteorological conditions may contradict research conclusions. However, it is important to remember that the 2005 hurricane season, which bore the destructive hurricanes Katrina, Rita, and Wilma, occurred during neutral ENSO conditions. If more named storms were to form, the chances of a hurricane again making landfall on the U.S. mainland would increase substantially, posing an immediate threat to industries like sugar and citrus. The flipside to this coin is that, with the disappearance of La Niña, the risk of drought in the Grain Belt may decrease some.

Higher-than-average rainfall can be just as detrimental to grain crops as drought, however. As we have seen in recent weeks, corn and soybean farmers have received an abundance of precipitation. Plantings have been delayed in much of the Grain Belt, and uncertainty remains as to which crops farmers will devote their acreage. Changes in forecasted acreage would certainly lend volatility to the grain markets, which are already tumultuous enough as it is.

McKeany-Flavell has nearly 60 years’ experience helping customers with their commodity needs. For more information about how such weather trends may influence your commodity purchasing decisions, or to discuss other commodity-related questions, please contact us.

McKEANY-FLAVELL COMPANY, INC.