Gavin Kenny: Farmers too dependent on irrigation systems

A significant part of our dairy industry has become dependent on irrigation.

My expertise is with climate change. It's been my professional work now for 24 years.

In the 1990s, scientists were cautious about making links between extreme weather and climate change.

This caution was increased by frequently made accusations that any suggestions of negative consequences in the future were alarmist. There is now clear evidence that globally, we are experiencing a greater frequency, and in some cases greater intensity, of extreme weather events.

Climate change is increasingly an underlying influence. Yes, we continue to experience natural variability, but underlying this is an undeniable influence from climate change.

This is the global picture that New Zealand is part of. For example, a recently-published study in the United States shows that with climate change, the south-west and Great Plains will suffer decade-long droughts far worse than anything experienced over the past 1000 years. Some areas in this region have already experienced drought in 11 of the past 14 years.

Along with changing climate and its influence on the weather we experience, we have seen dramatic changes in farming systems in New Zealand over the past 20 years. These changes have had a huge impact on how we deal with drought.

For example, if you look at wheat growing statistics for Canterbury from the first half of the 20th century, you will see fluctuations in area grown and yield. The total area in production varied dramatically between dry and wet years, with a contraction to the deeper soils in dry years and an expansion into the shallower, stony, soils in the wet years.

In the traditional dairy production areas of the Waikato and Taranaki, historically there were low enough stocking rates and sufficient feed in store to see farmers through all but the worst droughts.

Part of the message here is that we can't simply blame the weather. I've spoken to enough farmers and growers over the past 14 years who acknowledge we're pushing the margins a lot more with our food production systems.

The more you push the margins, the fewer options you have. We now have a significant part of our dairy industry dependent on irrigation. While some are arguing that with climate change we will need this even more, I argue the opposite.

It's common sense to me that the more you build dependency on something, the harder you're likely to fall. And this is backed by lessons from many failed civilisations throughout human history. If you're interested to know more on this, I would highly recommend a read of Brian Fagan's The Long Summer: How Climate Changed Civilization.

As a climate change scientist, I'm constantly working with 'what if' questions. When I've asked New Zealand farmers the 'what if' questions, through the various climate change adaptation projects I've completed since 2001, the answers I've received have been focused on the need for building climate-resilient farming systems.

Such a focus requires us to adopt an agro-ecological approach, to build functional diversity in a manner that is compatible with local environmental conditions. It involves consideration of the whole farm picture, encompassing soil management, the diverse roles of trees, stocking policies and management, pasture management, water storage and reticulation, and waste management.

There are increasing numbers of farmers moving in this direction. A good example is Doug Avery in Marlborough.

Around the time I was working with Doug, he took a trip to Vietnam and I think that trip, along with his own experiences with drought, opened his eyes to the bigger global picture that he is part of.

We all need to be looking at this bigger picture and thinking hard about the sort of farming systems we're going to need in the future, and start acting now.