Is La Niña on the way?

Nari, Normal
Source:

The National, Tuesday February 9th, 2016

 By seniorl anzu

THE Seasonal Climate Outlook for the first quarter of 2016 (Jan-March) indicates that the current El Niño may weaken during this period. 

Such indications, based on some of the world’s known climate models, should give Papua New Guineans a sigh of relief after being through the warmest year (2015) on record. 

Suppose the El Niño drought demises in March or May, what comes next? La Niña? 

A known fact with historical records is that La Niña follows on from El Niño. La Niña is a much wetter condition that usually follows on after a very strong El Niño. 

 Both La Niña and El Niño are the work of the sea temperature in the Southern Hemisphere. 

They are results of air pressures over the sea and the circulation of air across the sea; moving backwards and forwards from one extreme to another through what is known as the El Niño-Southern Oscillation (ENSO) phenomenon. 

 During an ENSO event, excessively dry and wet periods often occur one after the other in a sequence. 

As a result, ENSO can bring both drought and flooding rain to PNG.  

 La Niña occurs when the sea-surface temperatures in the central and eastern tropical Pacific ocean are cooler than normal. 

It recurs every few years and can last up to two years with impacts on global weather patterns. 

When eastern and northern areas of Australia experience wetter conditions, there is a high probability of La Niña occurrence in the Pacific including PNG. 

La Niña is closely associated with tropical cyclones and are known to occur during the cyclone season – November to April. 

The devastating Cyclone Pam brought on one of the worst disasters to Vanuatu in March last year. Exactly 12 months before Pam, Cyclone Lusi shocked the Pacific – Fiji, New Zealand and Vanuatu – with some impact in the latter. 

PNG’s Cyclone Guba in November 2007 affected the country immensely, particularly the Northern, destroying food gardens, homes, environment and infrastructure.   

PNG is currently in the cyclone season. 

However, it does not receive frequent cyclones like other Pacific countries. 

Vanuatu, being in the hotspot of tropical cyclones in the region, is expecting at least two cyclones in the 2015/2016 cyclone season, as possible impacts of the present El Niño. 

While the weather pattern is expected to change, the PNG National Weather Service is monitoring the situation. Its first quarter Seasonal Climate Outlook has not ruled out La Niña as PNG proceeds into the peak period of the El Niño. 

If anything, official announcements will be released.

Looking back, the 2015 El Niño drought event started somewhere around April-July. 

From August onwards, the drought situation became widespread with the high altitude highlands experiencing frost occurrences.  

After a drought a lot of plant cover is dried up. 

When the rains return, floods are experienced and exposed soil is washed away.

The country usually receive high rainfall due to its high mountain ranges which force the prevailing northwest and southeast (trade) winds to go over them. 

While PNG agriculture generally are adaptive to deal with soil-water, excess levels of water affect food production

It must also be noted that flooding destroys food gardens and access to food supplies. 

Fungal diseases and pests become problems during the wetter periods. The popular sweet potato struggles to tuberise, instead it produces alot of leaves and wines. 

In fact, excessive rain saturates the soil; reducing sweet potato yields. 

In past instances, there were cases of malnutrition especially among children and vulnerable families, which some tree crops changed their cropping seasons.  

When food is scarce, people suffer. 

PNG should prepare for post-drought recovery, and the sustainable approach is agriculture; firstly with early maturing crop production for immediate recovery through the availability of food. 

There are a number of post-drought coping strategies recommended by NARI based on its research following the 1997 drought. 

These include early maturing varieties of sweet potato, cassava and others for different agro-ecological zones. 

Communities should also use their indigenous knowledge for recovery during such situations. 

With the rains that are received, and the likelihood of improvement in the situation hopefully in the next couple of months, it is now high time to plant the gardens. 

That said, people should be vary of the amount of rain received in different pockets of the country. 

Some places are receiving more rains than others. 

There are some districts with excess rain resulting in heavy flooding; washing away of food gardens, homes and bridges. 

Communities should determine situations and decide on where and what materials to plant during this rainy season.

 

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