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Adapting Hawke’s Bay to Climate Change

Bridget Freeman-Rock01 February 2019

BB45

With global warming, Hawke’s Bay faces a warmer, drier, stormier future, which, on the surface of things, looks to be a mild prognosis. “Droughts are nothing new,” I’m told. “We’re a maritime country, we’re used to variable weather.” “I wouldn’t mind less frosts.” 

We tend to judge the future by what we know.

But on our current trajectory (with global greenhouse gas emissions reaching record heights in 2018) the planet will be 4C warmer than pre-industrial times before the end of this century (the Paris Accord was to keep it well below 2C). What’s important to understand is a further raise to the 1C increase we’ve reached now won’t unfold as a linear, evenly rolled-out probability, but bespeaks volatility and disruption to every facet of our biosphere. 

Key to helping me unpack how this might play out in Hawke’s Bay is the Regional Council’s CEO, James Palmer, who is also a board member of the Deep South National Science Challenge, a 10-year project (currently in its 5th year) to develop the tools and frameworks to understand, predict and respond to future scenarios in New Zealand. 

Palmer visited Antarctica some years ago and has witnessed firsthand the changes happening there. He believes the consequences will be profound: “The melt is real, it’s extremely rapid and it’s on a scale that’s utterly breath-taking.” 

Rising seas and liquid soils

Haumoana has become the pin-up poster for coastal erosion and sea-level rise (certain to rise 1m by 2100 under a 1.5+C global warming scenario) both for the ocean’s visible encroachment and for HBRC’s adaptive pathways coastal strategy, which is seen nationally as leading the way on local government response. 

With much of our coastal development less than 0.5m above the high spring tide mean, Haumoana is one of our coastal communities staging a managed retreat from the shore over the coming century. The first stage is to buy time with coastal barriers. In the meantime, insurance companies are signalling their retreat from what is an entirely foreseeable red zone.

By 2040 the sea will have risen 30cm; if we can’t level global warming, by 2118 this could be 2m and rising.

But it’s not just those living close to our coasts who will see the impacts of global warming unfold, and the inexorably rising seas are just one expression of what will inevitably be a rapidly changing world.

James Palmer points to the little ripples you can see scoured into our hillsides like stretchmarks. “If you could put a time-lapse photo on those, do a visualisation of the whole of Hawke’s Bay over, say, 100 years, what you’d see is basically all our soils being like liquid, sliding off our landscapes into our lowland and then coastal environments.” 

It’s a disturbing image. For soil loss, driven to a huge degree by land clearance (and we’ve cleared over 80% of our vegetation), along with the associated availability of water drying up, is bad news for agriculture, indeed for the future of civilisation itself, as has been repeatedly shown around the planet over millennia. And it’s greatly exacerbated by climate change. 

It’s inevitable, says Palmer, that an alteration of atmosphere and rainfall distribution – a key variable in a highly interconnected, dynamic system – will have a change-effect on the landscape. What this means for Hawke’s Bay is unclear, although with less rain when and where we need it and heavier rainfalls projected, “we do expect more erosion and sedimentation but potentially more gravel as well,” and more gravel heightens the risk of flood inundation while reducing the performance of stopbanks. 

Floods

Tangoio Marae is a wahi taonga for the hapū who gather there, but its future hangs in the balance. For the small settlement of Tangoio climate change is already a reality, in a catchment that’s one of Hawke’s Bay’s worst flood zones, on a coastline exposed to rising seas. 

The low-lying plains in the Te Ngarue catchment are subject to severe flash floods, with compounding issues of sediment and silt run-off from steep terrain to the north – a legacy of land-use (farming and forestry) combined with fragile pumice soils. NIWA hydraulic modelling shows projected rainfall/run-off increases, together with sea-level rise, will increase both depth and intensity of flooding, particularly with ‘Bola type events’.

Chair of the marae committee, Pereri King, says although they are exploring all options, including relocation, the hapū have little choice but to stay and protect. (Maungaharuru-Tangitū hapū once moved seasonally between coast and mountain but these 4 ha in the Tangoio valley are all that remain in landholdings of the vast tracts of land confiscated by the NZ government in the 1860s.) This means developing and strengthening the surrounding stopbanks. It also means the prospect of building new facilities that are uninsurable. Of nearly 6,000 registered marae members, two-thirds are under 25 years of age.

Pereri King says climate change adds further to the weight of Māori, and while his people are “survivalists”, he’s hoping for a miracle solution.

Weather modelling 

Traditionally Hawke’s Bay’s rain falls largely in the winter months, from a south-westerly flow across the country, followed by long, hot summers. Global warming will change rainfall patterns and distribution. But at this stage the observable change is relatively imperceptible, says HBRC climate scientist Kathleen Kozyniac. Weather projections for Hawke’s Bay show considerable variance; the most reliable climate change indication (aside from evident temperature and sea rise) being a decline in frosts.

The problem is there are roughly 40 extant climate models for long-range predictions (most with a northern hemisphere bias); NIWA has drawn on six to forecast for our region. 

To remedy what has been “a critical gap” the Deep South National Science Challenge (hosted by NIWA) has been developing an ‘earth system model’ specifically tailored for NZ conditions, and calibrated against 50 years’ of observed and recorded climate patterns here. It will give us finer scale predictive capability for what climate change will deliver by way of rainfall, etc. It will begin “spitting out predictions” sometime next year, and James Palmer says HBRC will be “watching that very closely”.

He envisions that the model will become “a national tool – much like the Met service provides us with days and weeks, this will provide us with months and years.” And expects it to show an increased intensity of extreme weather events, particularly as a consequence of our geographic location, with strong oceanic influences and more tropical systems moving down from the north.

Storms

Ian Macdonald, who heads the Hawke’s Bay Civil Defence Emergency Management team (14 full-time staff and 250 trained volunteers), is already planning for an escalation of extreme weather-related events. “There will be more of them and they’ll be occurring outside the traditional seasonal zones, for example, more cyclone-type events in summer.”

“We deal with risk, and risk is a function of the likelihood and the consequences of an adverse event. From our perspective, climate change will not only make existing hazards worse…but changes our risk profile over time.” While Hawke’s Bay’s greatest hazards are currently earthquake and tsunami, extreme weather events (currently at number 5 on the list) may become our number one hazard, says Macdonald, as we see 1-in-100-year weather events more regularly experienced. 

Stopbanks have effectively remedied flooding on the Heretaunga Plains, enabling horticulture and protecting our townships, so much so that we’ve ‘forgotten’ the risk, he says, creating infrastructure and economic investment in areas that were once more prone to flooding. “With climate change leading to more extreme weather events and inundation, our stopbanks will no longer be adequate – we either risk losing the productive activity either side or need to invest substantially in building bigger stopbanks and wider beams, to anticipate and withstand greater flooding events.” 

HBRC is looking to upgrade its flood and drainage infrastructure from a 1-in-100 to a 1-in-500 annual exceedance probability, which will cost tens of millions of dollars in all likelihood, and even then won’t provide certainty of protection. “Much like the conversation on the coast about defence versus retreat, at some point the costs of defence exceed the benefits,” says Palmer. “It may be that we need to think about sacrifice areas where some extent of flooding is deemed acceptable.”

CDEM has been undertaking its own hazard research and impact analysis: “Our focus is working with communities,” says Macdonald, “developing resilience within communities and individuals. And being as ready as we can be for response…as well as recovery.”

Macdonald points out that a big weather event, like Cyclone Bola, can disrupt the sectors we’re most dependent on – tourism, agriculture, horticulture – and statistically we’re well overdue. So “how do we bounce back from something like that?” It can take years.

One of the big issues for the region, Macdonald says, is around local-source tsunamis as the result of a large nearby earthquake off our coast. Napier will be in an increasingly vulnerable position with climate change – under a worst-case scenario, the inundation zones will cover up to two thirds of the city, thus upping both the impacts of a tsunami and the evacuation safe zones.

Horticulture 

Flooding aside, our apple boom looks safe for the moment, in terms of industry projections (which are predicated primarily on temperature changes), and even offers opportunities for landuse changes that could help us meet our Paris Accord conditions, with high-value yields per ha, low GGE and carbon sequestration potential. 

Brent Clothier and Alistair Hall, scientists at Plant & Food Research, say impacts on horticulture in Hawke’s Bay will be reasonably modest – under the extreme scenario harvest dates for Royal Gala apples, for example, will come forward two weeks by 2050, with a reduced growing season. 

They speak of a three-tiered adaptation approach, the first being tactical (eg. changing pruning schedules or spray programmes), which horticulture, as a highly interventionist system does constantly, modifying practice to respond to, and control, any number of variables, season by season. 

The second, strategic: “Different varieties, different practices”. For example, Plant & Food is breeding new varieties of fruit tolerant to climate change; golden kiwi (which tolerate warmer winters) may replace Heywoods green in frost-free areas; orchards may install nets to protect crops from hail. 

Thirdly, transformational adaptation – adopting new crops, growing in new locations. While we may see more kiwifruit production in our region in future, the biggest change may be the migration of apple and pipfruit production south into the Ruataniwha basin, which has formerly been too cold for growing much more than grass.

A shift from farming animals to vines and orchards could lower the country’s GGE substantially (courtesy of agriculture, we’re one of the biggest per-capita GGE-emitters), and with the window on mitigating global warming fast closing (we have a decade, basically), there’s more at stake here than opportunity.

Vines

“My art work is a way of recording what’s happening at ground level.”
SUSAN MABIN, ARTIST

Te Mata Estate wine-maker Peter Cowley says he doesn’t feel threatened by climate change … yet. Warmer temperatures could well be a boon for HB red wines, which sit at the cooler end of the Bordeaux-type growing spectrum, although “once you get up to 38C days the vines will struggle”. They stop photosynthesising and you don’t get the tannins, colour, or flavours ripening.

He notes that overseas climate change is talked about constantly – hotter wine-growing regions like South Australia are “having a terrible time”. But here in a more buffered climate, the hardy, adaptive nature of viticulture means it’s relatively well-placed to cope (“though I wouldn’t be promoting syrah”). 

“We are constantly aware of the how the vintage is going,” says Cowley, and can respond to disruption as it happens, harvesting earlier if need be or downgrading from a top-wine to a still-good bulk blend.

Te Mata has several vineyards around the Bay with quite different micro-climates where different grape varieties are grown – while it wasn’t a strategic decision, it does put them in more a resilient position, says Cowley.

Grapes have a relatively low water-demand and precision irrigation means inputs are ever-less, but lack of water, especially with gravelly soils, would spell trouble. “If we ran out of water, after 2-3 weeks vines don’t bounce back.”

And there’s the rub…

Water security

We’re now at a point where the groundwater resources of the Ruataniwha basin and the Heretaunga system are fully allocated (and not, as CHB has discovered, necessarily equitably under our ‘first in, first served’ legislation). 

Lowering the groundwater table obviously affects those with shallower bores, but also drops the water levels of our streams and rivers, impacting both the ecology and amenity values of our waterways. And climate change will twist the screws.

With disruption to the steady, predictable seasonality of water coming into the system, we may find ourselves going into summer months with less groundwater resource than usual, while periods of low rainfall (i.e. drought) will result in greater irrigation demand on depleted resources. More worryingly, says Palmer, a 1C increase in temperature significantly accelerates the evapo-transpiration rate, so the efficiency of our irrigation systems will drop.

“We run the risk of there being increasing demand on our water resources to sustain even our current levels of production.” Increased irrigation efficiency by way of technology and production practices will become imperative. 

Although HBRC is currently looking at two propositions for water storage (managed aquifer recharge in the Ruataniwha basin and above-ground storage systems; stream flow augmentation in the Ngaruroro catchment), “our emphasis is on security of existing use, including municipal supplies for Napier and Hastings.”

Health impacts

Professor Alistair Woodward of Auckland University says an increase in droughts and a reduction in rainfall on the east of the country will put a lot of pressure on our rural economy – and mental health problems among those working in the rural sector correlates strongly to how well (or not) the rural economy is performing. “Communities under stress – that’s something we have to anticipate and prepare for.”

While we won’t see the extremes of heat experienced elsewhere around the globe, more hot days will increase incidents of heat stroke, aggression and heart disease, especially for outdoor workers, and with air quality expected to decline, we’ll see an increase in respiratory problems. Droughts, floods and increased temperatures may lead to water contamination and toxic algal blooms; mosquito-borne diseases, like malaria, may reach our shores. 

“Think of climate change as a threat multiplier,” suggests Woodward. Adding that the outcomes won’t be equally distributed, with those most vulnerable likely to be hardest hit.

Fire 

While Queensland burns with record-breaking heatwaves and unprecedented wildfires, hot on the heels of California and the annihilation of Paradise, it’s sobering to consider that warmer, drier conditions on our east coast could extend the high-extreme risk period for wildfires to 4-6 months of the year by 2040 if we cannot keep warming in check.

What of the regional council’s afforestation plans, which will surely add fuel to that risk?

James Palmer says, “it’s an enormously difficult set of trade-offs” because forests are both our smartest carbon sequestration strategy and the best way to mitigate against the drying effects of warming, but when they burn, they release all that carbon into the atmosphere. 

HBRC is currently looking at what to plant where, “and future fire risk is part of that overall calculus”. Native forests have a lower burn risk, while eucalypts and radiata are more combustible, for example, reinforcing the need for forest diversity. 

While fire is one of the scarier outcomes of climate change, the thing Palmer finds scariest of all is “the upset to the predictability of the seasons”. Climate stability, which enabled life as we know it to flourish, has been borne of the extremes between the weather systems at the poles and the equator. “As a consequence of climate change, the poles are warming much faster than the equator, so the differential between the two is closing and as a result, the stability between those systems is breaking up.” 

In New Zealand, “What we’re now seeing is more warm spells in the middle of winter, unpredictably and for short periods of time, and then we’re getting cold snaps in the middle of summer. So, while there’s a warming trend, there’s actually more variability and perturbations, and trying to grow things in that environment, whether it be a vegetable crop or horticultural crop: incredibly challenging.” Not to mention for our indigenous ecosystems, which will have to adapt to variances in their food source and reproductive life cycles. 

Money 

Whether it’s transitioning to more diverse, sustainable land-use practices to build resilience into our landscape and regional economy, upgrading flood protection infrastructure, planning coastal work, transport futures or water storage, global warming is going to cost considerable sums of cold hard cash. 

The proportion of household income in NZ spent on climate change adaptation is set to dramatically increase over the next few decades. 

HBRC is considering making it the focus of their next long-term plan, says Palmer, with a step-change in capital investments and a mix of public-private funding approaches likely. Staff are working to pull together “a whole-of-organisation view of climate change … to identify where the gaps are and ensure that we’re applying resources as best we can.” 

A warmer, drier, stormier, more uncertain future will throw up difficult decisions and challenges we can neither insure ourselves against nor fully foresee. We will need to think hard about our priorities and what we truly value. 

“There’s no free lunch in any of this,” says Palmer. “All of the options in the future will incur cost within the community and involve some level of ongoing risk. This is the reality we face with the change in climate.”

 

10 alarming projections for Hawke’s Bay

How does Hawke’s Bay fit into the equation when “the collapse of our civilisations and the extinction of much of the natural world is on the horizon” (David Attenborough) and nothing less than radical, immediate change will turn the ship from the brink of global disaster? 

1. Soil erosion 

Soil erosion is expected to accelerate with climate change – at the current rate of annual loss, we stand to lose it all from our hills within a century. Goodbye agriculture, hello desert.

2. Wildfires

On a warmer, drier east coast, by 2040 we may be facing a high-extreme risk of wildfires 4-6 months of the year. We urgently need more landcover (for the soils, for resilience, for carbon sequestration), but if we don’t plant trees now we’ll be chasing our tail, as the forests that will mitigate drying (and thus fire risk) will paradoxically increase the risk and danger under warmer, drier conditions.

3. Storms and flooding Storms and flooding may become our number one natural hazard, with 1-in-100-year weather events occurring more frequently, and a higher probability of 1-in-500-year exceedances. We need to invest millions in upgrading our stopbank and stormwater networks, and we’ll need to consider ‘sacrifice areas’.

4. Tsunami risk

Rising sea levels combined with more extreme weather events, mean even a small tsunamic event could have colossal impact, and coastal Hawke’s Bay faces a high tsunami risk (read Keith’s article, p66). A small tsunami will close the airport and port, for starters, and damage Napier’s wastewater system (in low-lying Awatoto), and that’s just the public infrastructure.

5. Sea-level rise

Current emissions put us on target to bequeath future generations a 5-10+ metre sea-level rise by 2300, which would completely redraw the map for Hawke’s Bay; two thirds of Napier will face inundation within a century. Clifton, Haumoana, parts of Clive, under the rosier 1.5-2C scenario will have undergone managed retreat. 

6. Insurance 

Insurance companies bail: homes in low-lying areas will become uninsurable in the near-future (and thus unmortgage-able and devalued), eroding communities – those remaining will be the vulnerable with nowhere else to go. Higher seas risk widening the economic divide. (Stuff.co.nz has an excellent interactive feature on this: Beach Road)

7. Climate change impacts Māori disproportionately. Māori are more likely to live in low-lying areas, with higher engagement in coastal activities (eg fisheries) that will be climate disrupted. Acidifying oceans, as a result of increased CO2 in the atmosphere, are already affecting the growth and shell-formation of paua. Climate change will also exacerbate respiratory illness and poor housing (damp, mould), issues with higher statistical representation of Māori.

8. Horticulture 

Horticulture will potentially face increased hail storms and damaging summer rainfalls, and more biosecurity risks – pests, disease – though how this plays out is an unknown quantum. Seasonal instability will be massively challenging for all growers.

9. Water security Water security is a biggie. Already our aquifers are fully allocated, and with lower winter/spring recharge predicted and higher evapo-transpiration rates, our freshwater resources will become worryingly constricted. Some productive landuse activities will no longer be viable.

10. Wine

And for those who love wine, Hawke’s Bay’s hip syrah: gone… Climate change will also rob the zing from our sauvignon blanc turning it undrinkably flat. If that’s not a reason for action…

Adaptation Toolkit 

• Diversify 

Not monocrops or silver bullets, but multiple, multi-pronged approaches: a patchwork of land-use and land-cover.

• Plan for the future HB Coastal Strategy is an example of a forward-looking, multi-staged, dynamic plan for responding to the treats posed by rising sea levels.

• Prioritise Where/how do we invest protection, what do we sacrifice, what are our values, how will we fund this? Climate change is going to hurt, however we cut it. 

• Be nimble 

With an unpredictable environment, adaptation will need to be continuous, fluid, to meet both risks and opportunities. Viticulture is an example of a sector that can make micro-adjustments. 

Build resilience

In landscape, productive systems, communities – through environmental, social, economic and cultural sustainability. 

• Make art 

It’s a viable way to process and make sense of things; it’s also a carbon-neutral activity. 

Unison is pleased to sponsor robust examination of energy issues in Hawke’s Bay. This reporting is prepared by BayBuzz. Any editorial views expressed are those of the BayBuzz team and do not reflect the views of Unison.

 

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Bridget Freeman-Rock01 February 2019

BB45

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