Historically, agriculture has proved to be fairly adaptive to changing environmental conditions,
but this may not hold true in the present global climate change scenareo. Worldwide, land and ocean
temperatures are increasing at unprecendented rates, raising the global average sea level and
significantly altering the intensity and distribution of precipitation events, thus bringing more frequent
droughts, floods and sea inudations, particularly to tropical latitudes (IPCC, 2007). Papua New Guinea
(PNG), situated on the western rim
of the tropical pacific, is being
affected not only by global
warming, as shown by recent
annual temperature increases (Fig.
1) and rising sea levels, but is also
vulnerable to extremes in rainfall
intensity linked to the El Ni?o
Southern Oscillation (ENSO). The
most widespread food shortages in
PNG have resulted from severe
drought conditions brought on by
strong El Ni?os. Interspersed with
these events have been excess
rainfall conditions, linked to La
Ni?a events, which have been
almost equally detrimental to crop
production, since excessively wet
conditions prevent sweet potato,
(PNG’s staple food crop) from producing tubers (Bourke, 2005) and trigger fungal diseases in this and
many other crops. The threat posed by disease is particularly concerning because of the narrow genetic
base of PNG’s sweet potato germplasm, and the risk that local varieties would be unable to cope with
increased disease pressure under warmer/moister conditions, and indeed there is evidence that this is
happening already. The 1997 El Ni?o drought was unexpected because an event of such severity had
not occurred since 1914. Scientific evidence suggests, however, that this event was the strongest in a
series of strengthening El Ni?os that are now recurring every 10-15 years and giving rise to food and
water shortages throughout much of PNG, and that another major event is likely around 2012. In response to the threat of climate change, a series of projects are being developed by NARI in
collaboration with other agencies and overseas institutions in a 4-part multidisciplinary research strategy
aimed at mitigating the impacts of global warming and ENSO activity on food production in PNG.
As the first line of defence, an early warning system is being developed through an ACIAR
(Australian Centre for International Agricultural Research) funded project entitled “Early warning and
drought preparedness for improved management of crop production in PNG”. This will involve the
development of a drought forecasting and early warning system for PNG through customization of
SCOPIC (Seasonal Climate Outlooks for Pacific Island Countries) software and the use of historical
production data for important subsistence and cash crops (sweet potato & coffee) to provide models
capable of predicting the impacts of various climate change scenarios on production.
The second and more fundamental risk aversion stratagem is the diversification of genotypes and
cropping systems to allow for unforseen as well as predictable impacts of climate change on crop
production. This will include the preservation and broadening of existing national gene pools of staple
crops such as sweet potato to ensure ample genetic scope for
crop adaptations in future climate change scenarios. It will also
involve the selection and breeding of crop varieties with
genetically imparted tolerances to biotic and abiotic stresses.
Already a breeding and hybridization program is underway to
develop early maturing, high yielding recombinants of sweet
potato to facilitate the speedy recovery of food production
following drought or excess rainfall conditions. Further work
is also in the pipeline to screen highland and lowland sweet
potato germplasm to identify genotypes displaying drought,
cold or excess moisture tolerance and resistance to viral and
fungal disease infections. These will then be crossed with other
elite local and exotic genotypes to produce high performing recombinant clones tolerant to a range of
biotic and abiotic stresses. As well as widening the gene pools of specific crop species, research will also
be conducted to evaluate the benefits of diversifying traditional cropping systems by introducing new
high-performing varieties of maize, rice, yam and peanut, etc. Such diversification should help to
prevent the build-up of host-specific pests and diseases and minimise the risk of outright crop failure due
to abiotic stresses e.g. frost or drought. Sustainable methods of maintaining soil fertility under such
diversified cropping systems will also be explored in a suite of ACIAR and NARI funded projects.
The third element in the research strategy specifically targets the problem of heightened pest and
disease outbreaks owing to climate change. Already PNG has suffered the virtual destruction of its
potato industry following the outbreak of late potato blight disease in the late 1990’s, and viral disease
and pest infestations of sweet potato and other crops are increasingly hampering production and
marketing. In response to these problems a series of ACIAR funded projects have been developed to
tackle the issues of late potato blight in ‘Irish’ potato, oribius weevils and virus attacks on sweet potato,
and fruit fly infestations in various crops. Biotechnological solutions are being implemented including
the micro-propagation and field testing of blight free and blight resistant potato clones, and the
development of ‘clean’ pathogen tested sweet potato planting materials. Biological, cultural and low
cost chemical methods for controlling oribius weevils and fruitflies are also being investigated.
The final element in the research strategy focuses on the provision of water supply facilities to
sustain crop production in a scenario of recurring El Ni?o-induced drought events. Regional
geological surveys are needed to investigate aquifer accessibility and terrain suitability for the
construction of mini-reservoir, spring and borehole supply facilities in the five main agro-ecological
regions of PNG (high altitude highlands, highlands, dry lowlands, wet lowlands and islands).
Community surveys will be needed to establish local preferences for specific types of water supply
and to deal with water and land ownership issues. Thereafter, pilot studies will be needed in each
region to assess the feasibility, practicalities, costs and effectiveness’s of the different methods of
supplying water for (drinking and) crop irrigation. NARI has identified a number of partner
organizations, including water institutes in Europe that would assist in the research and development,
but substantive government funding will be needed if the initiative is to proceed.