climate change

Challenges for food producers as the climate changes

By Anna Campbell

The breeding of semi-dwarf wheat was pivotal in starting the green revolution. Dwarf wheat was developed in Mexico in the mid-1940s-50s by Dr Norman Borlaug, a geneticist, plant pathologist and Nobel Peace Prize winner. Very simply, dwarf wheat plants can remain upright. They don’t fall over from their own weight and lie on the ground rotting and their stems don’t often break on a windy day. Dr Borlaug’s invention is credited with saving billions of lives after he spent his subsequent career introducing dwarf cereal varieties to Pakistan, India, China and regions of Africa.

Wheat is a big story on the world stage and mapping its history leads to many sub-plots and twists. Last year a fascinating scientific article was published, by Dr Zvi Hochman and colleagues, in Global Change Biology. Australia is one of the world’s largest wheat producers and has an impressive history of increasing wheat yields. Yet, wheat yields in Australia have stalled since 1990, despite continual improvements of wheat breeds and technology which should have led to an increase in yields of up to 27%. According to Dr Zvi Hochman, this stalling can be attributed to reduced rainfall and rising temperatures, as measured at 50 weather stations throughout wheat growing areas of Australia. Quantitatively, Australia’s wheat-growing zone has experienced an average rainfall decline of 2.8 mm (28%) per cropping season, and a maximum daily temperature increase of around 1℃ from 1990 to 2015. Statistically, the chance of this happening through random seasonable variability is less than one in 100 billion. Yes, you guessed it, declining wheat yield is a sub-plot of the wider story of climate change.

When these climate effects are mapped, they are not evenly distributed, with parts of Western Australia among the hardest hit. It does make you wonder, what are the agricultural indicators of climate change in New Zealand and where has been hardest hit? It is hard to find such an elegant back-story as the Australian wheat story, but there are plenty of predictions of what might happen in the future. NIWA scientists have predicted that the main green variety of kiwifruit, Hayward, will no longer be commercially viable in the Bay of Plenty in 50 years’ time, because of its requirement for winter chilling. Perhaps areas further south will become viable for kiwifruit growing instead. I have heard anecdotal evidence from farmers and industry specialists of changing weather and production patterns – as an example, facial eczema, a fungal livestock disease causing liver damage, is said to be moving further south as the climate warms. The questions for many of us are how do we mitigate the impacts of climate change and how do we adapt?

Too often we look for a simple answer, or a culprit to blame - which brings me back to Dr Boulag. The simplicity of his invention, dwarf wheat saving a billion lives, is a fabulous story, but like most simple stories, biology, ecology and humanity are more complex than the introduction of one gene. These days, Dr Boulag has his detractors – the high-yielding wheat plants he produced required expensive fertilisers and more water, both of which have contributed to the down-sides of industrial agriculture – rural impoverishment, increased debt, social inequality, displacement of vast numbers of peasant farmers and of course, climate change.

In my mind, Dr Boulag was neither a hero nor a villain, rather, he was an excellent applied scientist with a drive to support food growth in developing countries. Similarly, agriculture is neither the hero, nor the villain in climate change, rather it is part of the problem and part of the solution. Food production, climate change and the environment we live in are multifaceted and complex – all of us must learn from the past and adapt for the future, and somehow, do it together without constantly playing the blame game.