How ENSO affects food production

 By JAMES LARAKI

AN El Nino-Southern Oscillation (ENSO) event has different impacts on food production, depending on its severity and on the type of food production system affected. 

There are three main types of food production systems used in Papua New Guinea. These are shifting cultivation systems, continuous cultivation systems, and sago systems. Shifting cultivation system is the most common of all, though this is likely to change with the growing population and arable lands taken up for other development purposes.

People engaged in shifting cultivation usually clear new land for planting towards the end of the dry season to ensure new crops receive enough water from the expected rains. In most cases, they would use fire to clear bush land for cultivation.

During an El Nino event, vegetation on fallow land gets dried up and fires used for clearing land for cultivation can get out of control. It could destroy other gardens, houses, animals, and even kill people. The destruction to vegetation on fallow land can extend the time it takes for land to be ready for cultivation again.

If rain is delayed, new crops planted do not get established and have to be replanted after rain has fallen. When that happens, people may experience shortage of seeds and planting material. During prolonged dry periods, people may be forced to eat crops they would normally reserve for planting and may have little or nothing left for planting when rain falls.

This means people may have to source seeds and planting materials from elsewhere, leading to delay in planting new crops. Over 100,000 families were faced with this scenario during the 1997/98 El Nino event.

Heavy rains and longer cloud cover periods can reduce production from shifting cultivation gardens, but the effects of too much rain on many crops is not well understood. The noticeable continuous food production systems are the continuous banana production systems in the lowlands and sweet potato in the highlands. There are a number of areas in the lowlands where bananas are produced continuously for a long periods from the same piece of land. 

The continuous banana production systems are known to be resilient to most climate upsets and will only be impacted by very strong ENSO events. Such events may stop bananas from producing for some time but will restart production when the situation improves. Like all mono-cropping systems, bana­nas can be disrupted by pests and diseases incidents.

Sweet potato systems, however, are vulnerable to excessive water as well as low temperatures. Continuous production is achieved by continuous planting. If continuous planting is disrupted, or if the tuber production is interfered with during formation or maturing stage, then the production of food will certainly be affected. 

Disruption to sweet potato pro­duction either by climatic events or other causes will lead to serious implications on the overall food production in PNG. This is because sweet potato is the most important food crop, providing up to 30% of total calories consumed in the country. It is the most important food for over 60% of the population. Sweet potato is the main staple in the highlands, including for domestic pigs. Pigs eat up to half of the sweet potato produced, usually the small tubers that are considered unfit for human consumption.

The other important food in PNG is sago, eaten by some 600,000 people as their main staple. Sago does not grow above 1100m above sea level. Most of palm harvested is wild, while some may be cultivated. Where wild sago is used, it is likely that people may not know how to plant new palms.

An ENSO event may not have any serious impact on sago, but bush fires due to prolonged dry periods may kill palms as was the case in certain parts of country during the 1997/98 El Nino event. 

While other factors may lead to food shortages in PNG, the most common causes of widespread food shortages are usually the result of climatic events interrupting food production sy­stems. Food shortages are a result of crop failures due extreme climatic events and the way the people respond to such situations. It is difficult or impossible to control the climate but we can find crops that are better adapted to climate and we can educate the people about how to manage the crops better. 

To help us deal with such sit­uations, we need make a clear distinction between dry seasons, which occur every year in some places, and periods of very low rainfall that occur over most of the country from time to time. It is useful to note these have different impacts on food production systems.

Where there is regular dry sea­son, agriculture and food pro­duction is adapted to deal with the dry conditions that are expected to occur every year. Most of PNG does not have a dry season. Over much of PNG there is rainfall all year round. 

However, from time to time PNG suffers from a serious lack of rain in many parts of the country, including those parts that do not normally have a dry season. From time to time parts of PNG have periods of excessive rain. 

These low rainfall and high rainfall periods are certainly associated with the ENSO phenomenon. 

These situations will definitely interrupt the way we produce our food. Our level of preparedness will help us cope and respond to their likely impacts, including food shortages.