Climate change will
Climate change is altering conditions that sustain food production, with cascading consequences for food security and global economies. Recent research evaluated the simultaneous impacts of climate change on agriculture and marine fisheries globally.
Modelling of those impacts under a business-as-usual carbon emission scenario suggested about 90 per cent of the world’s population – most of whom live in the least developed countries – will experience reductions in food production this century.
New Zealanders are fortunate to live in a part of the world blessed with relatively fertile soils, adequate water supplies and mild temperatures. This gives us a comparative advantage for agriculture and horticulture over many other countries, including our main trading partner, Australia.
New Zealand produces more than enough food for its population. Exports exceed local consumption, and climatechange-induced food shortages should not be an imminent risk. But behind every general statement like this lies some rather more troubling detail.
As residents of a developed country, we are accustomed to accessing the world’s resources through supermarkets. New Zealanders take for granted that most foods (even those we do not produce, such as rice or bananas) will be available all year round.
Asparagus, new potatoes and strawberries are examples of foods
New Zealanders may expect to see only at particular times of the year, but if apples or kiwifruit are out of stock, people complain. Our expectations are based on imports of products when they are out of season in New Zealand. The availability of those imports may be seriously compromised by climate change.
A recent Ministry for the Environment report describes climate impacts, including detailed projections of the average temperature increase and changes in rainfall patterns across New Zealand. The consistent trends are towards wetter conditions in the west, drier in the east, and the largest average temperature rises in the north. Implications for agriculture are manifold. For example, many temperate crops require cool autumn or winter temperatures to initiate flowering or fruit ripening. Orchards may need to be relocated further south, or novel low-chill varieties may need to be bred, as is already happening around the world.
Insect pests and diseases are normally controlled by our low winter temperatures, but they may become more of a problem in the future. Introduced pests and diseases include fruit flies that have a major impact in Australia and other more
tropical countries, but struggle to establish breeding colonies in New Zealand. Strong biosecurity controls are our best bet for reducing this risk.
What matters more than the gradual increase in temperature predicted by climate change models is the greater frequency of extreme weather events. These include droughts, floods and hail, which can lead to total crop losses in particular regions.
One obvious mitigation strategy is to expand the provision of irrigation in our drier eastern regions, but concerns over water quality in our rivers mean this is not a popular option with the public – for example on the Heretaunga Plains or in Canterbury.
New Zealand is a net exporter of dairy, beef, lamb and many fruits and vegetables, but for some products, we depend heavily on imports. Figures from the US Department of Agriculture are not perfect, but they highlight trade imbalances for major commodities.
New Zealand imports all rice and most of its wheat. It is a net importer of pork products. Horticultural data released annually in Fresh Facts show New Zealand’s major horticultural imports are (in order of value) wine, nuts, processed vegetables, coffee, bananas and table grapes. These