Climate change scientists have projected continued global greenhouse gas emissions would heat Northland heat up more than other regions - leadingto increased wild fires, flooding and coastal erosion, invasive pests and more drought by the end of the century.

In what reads like an apocalyptic fiction, the Climate Change Projections and Implications for Northland report warns that the region would also be hit with an increased risk of salmonella, dengue fever and Ross River virus and a threat to some crops, with some effects visible by 2050.

Commissioned by Northland Regional Council, Niwa climate scientist Petra Pearce and her team note that Northland's 25 annual days of recorded temperatures of more than 25C would increase to 100 days.

Niwa reported last week that Whangarei was the warmest NZ area in 2016, with a mean average temperature of 16.9C, making Northland the warmest region for the fifth year running.


The additional 75 hot days and a maximum average, annual temperature increase of 3.3C by 2090 would see Northland overtake Hawke's Bay and Canterbury as the hottest region overall with the largest temperature increase.

The localised report was calculated regionally from global data, taken from a number of Intergovernmental Panel on Climate Change (IPCC) reports, using historical climate data from 1986.

It considered four scenarios from the removal of emissions to the extreme "business as usual" scenarios until 2040 and 2090, Pearce told the Advocate.

"What stood out as the major change in Northland, was the increase in temperature ... higher than all other regions," she said.

The report projected that by springtime 2090, there would be a temperature rise of up to 2.8C in Northland, with 1-12 per cent less rainfall in Kaitaia and 3-17 per cent less rainfall in Whangarei.

In summer, there would be a 0.7C to 3.3C temperature rise and 2-6 per cent more rainfall in Kaitaia and Whangarei, while autumn would bring a 0.7C to 3.2C temperature rise and 1-5 per cent more rainfall in Whangarei, with up to 4 per cent increase in Kaitaia rainfall.

Northland could see more floods and storm damage such as this at Lemons Hill in 2014.
Northland could see more floods and storm damage such as this at Lemons Hill in 2014.

However, winter would see a 0.7C to 3C temperature rise, 6 per cent less to 1 per cent more rainfall in Kaitaia and 1-9 per cent less rainfall in Whangarei.

Pearce said the projections depended on the uncertain future global emissions and were not be taken as definitive.


Stormy weather would increase in intensity with more thunderstorms and wind with ex-tropical cyclones likely be stronger and cause more damage as a result of heavy rain and strong winds.

An increase of 7 per cent in drought frequency was also projected from 2030 and 2050, and up 10 per cent from 2070 to 2090, compared to 1980-1999 levels.

Pearce said the region could also experience an increase in the occurrence of summer water-borne and food-borne diseases such as salmonella, with an increased risk from vector-borne diseases [transmitted by bites] such as dengue fever and the Ross River virus.

Climate change would also result in an increased biosecurity risk from invasive pests, which would impact pasture and horticultural crops. Existing pests were at risk of becoming serious problems with even a slight increase in temperature.

Could Whangarei's Hikurangi Swamp be flooded more often?
Could Whangarei's Hikurangi Swamp be flooded more often?

The production of some fruit, such as kiwifruit, would no longer be viable by 2050 because of a lack of winter chilling with warmer temperatures, a longer growing season and rare frosts would require new sub-tropical crops, such as persimmon or macadamia.

Kerikeri grower David Kelly said growers would find ways to thrive, in spite of climate change, thanks to the Zespri-funded breeding programmes at Plant and Food Research in Kerikeri.

"Under the Niwa timeframe, it is doable to produce plants in 15 to 20 years which would withstand temperature changes."

He added that there was room for more irrigation innovation.

Meanwhile, Northland's sea levels would reflect the national projection with New Zealand tide records showing an average rise in relative mean sea level of 1.7mm per year over the 20th century.

The report said coastal roads and infrastructure would face increased risk from coastal erosion and inundation, increased storminess and sea-level rise.
To read the full report, click here.

You can also read the Ministry for the Environment's summary here.

Projected environmental changes by 2090:

* 75 more 'hot days' a year
* Up to 3.3C hotter in summer
* Double the time spent in drought
* Increased flood risk
* Coastal erosion
* Risk of salmonella, dengue fever, Ross River virus
* Increased biosecurity threat from invasive pests
* Uneconomic crops, kiwifruit (by 2050)