NZ Farmer - Water projects 'critical' as scientists predict run of even higher temperatures

Written by Esther Taunton

This year's northern hemisphere heatwaves could mark the start of a four-year run of higher global temperatures, a prediction that makes developments like the stalled Waimea Dam project even more urgent, IrrigationNZ says.

Heatwaves during the northern summer killed dozens in Japan and Korea, triggered wildfires in California and Sweden, and led to prolonged dry weather in the UK and across northern Europe, raising temperatures beyond 30 degrees Celsius in Scandinavian sectors of the Arctic Circle.

In Greece, deadly wildfires claimed at least 74 lives.

And worse may be to come, according to scientists. 

Researchers from the National Centre for Scientific Research (CNRS) in France, the University of Southampton and the Royal Netherlands Meteorological Institute said a new method for predicting average air temperatures suggested the next few years could be even hotter.

Using their statistical method, the scientists found temperatures were likely to be even higher than previously predicted based on current global warming alone, with a low probability of intense cold events before 2022.

In New Zealand, droughts represented a significant cost to the agricultural sector of the economy and were projected to become more frequent and more intense under climate change.

However, not every year that was warmer than usual globally would be hot in this country, Niwa chief scientist, climate, atmosphere and hazards Dr Sam Dean said.

"This is because whether we get hot weather or cold is also dependent on whether our wind blows more from the north or the south, and this is a very local effect.

"But it is also true that all things being equal the odds of a hot year here are higher when global mean temperatures are higher," Dean said.

"For example, 2016 was the hottest year globally since records began, and it was also the hottest year recorded here in the Niwa national temperature series."

As climate change continued, investment in well-designed water storage was critical, IrrigationNZ chief executive Andrew Curtis said.

"In hotter conditions crops need more water. Water makes a huge difference to plant growth – for example a wheat field which is not irrigated will only produce half the amount of wheat as a field which is irrigated," he said.

Projects like the proposed Waimea dam near Nelson and Hurunui Water Project in North Canterbury were critical to ensure the country could continue to grow produce and future proof local communities against the effects of a changing climate, Curtis said.

"Climate change will mean rainfall is more variable in the future with more frequent droughts as well as more intense rainfall events."

Tasman district councillors last week voted 8-6 against a draft resolution to proceed with the $102 million Waimea Dam project, citing concern over increased rates and possible delays for other capital projects if the dam went ahead.

However, councillors would reconsider that "no" vote on Thursday in light of the possibility of increased external funding, which would reduce the cost for ratepayers.

Curtis said by turning down the dam the council had lost the option to share the cost of the infrastructure with the region's growers.

"This decision is very short sighted when both Europe and Australia are suffering from severe droughts as a result of climate change," he said.

"Internationally there is huge government investment in water infrastructure occurring as other countries recognise that climate change and growing populations will put increasing pressure on water availability.

"California voted in 2014 to spend $7.5 billion on new water storage projects. In Australia over the past decade the government has spent $15 billion on rural and urban water projects and it plans to spend a further $2.5 billion on water storage."

The Waimea dam would allow water to be stored when it was plentiful to provide a reliable supply for residents and protect jobs in horticulture, construction, food processing and other industries that rely on access to water, as well supplementing the Waimea River's flow, Curtis said.

Opponents of the proposed 53-metre high dam, which had an initial pricetag of $76m, said the project would've benefited a select few and the views of urban water users were being overridden in the interests of farmers dependent on irrigators.