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Climate Change in Hawke's Bay

Here in Hawke's Bay we are already seeing the impacts of climate change - warmer temperatures and changing seasonal rainfall patterns.

What are the impacts of climate change in Hawke's Bay?

We are already beginning to see the impacts of climate change in Hawke’s Bay, and modelling shows that the impacts will become stronger and more frequent over time. Our communities have experienced the impact of severe weather events during Cyclone Gabrielle in February 2023. We know that rainfall is more intense and storms more frequent under increasing degrees of global warming.  This information comes both from weather attribution science  that shows that the rainfall associated with ex-tropical cyclone Gabrielle was both more intense (up to 20-30%) and more frequent (up to 4 times more likely) because of anthropogenic climate change – and that accounts for La Nina patterns.

Warmer temperatures and changing seasonal rainfall patterns will bring both positive and negative effects to the region. Our aim is to better understand the forecast changes so we can build resilience, prioritise actions and plan for the long-term.

The effects of climate change can contribute negatively to people’s health both directly and indirectly. In New Zealand, health impacts may come from reduced air and water quality, summer heatwaves, reduced water safety and challenges with mental health.

The impacts of emergency events, such as flooding, can also impact people’s homes, businesses and places of cultural or religious significance, it can lead to stress and anxiety as well as influence people’s feeling of safety or security.

Children, the elderly, people with disabilities and chronic disease, and low-income groups are particularly vulnerable to climate change-related health impacts. Due to existing health inequities, Māori are also particularly at risk.

As a maritime nation, much of New Zealand’s population lives on or near the coast. Flooding, erosion, loss of habitats for native species on both land and sea, and loss of coastal recreation areas are climate related impacts that will affect Hawke’s Bay. Variations to rainfall levels will also increase both the frequency of river flooding and droughts.

Rising seas levels increase coastal community and infrastructure vulnerability to floods, tsunamis and other natural disasters. As the ocean absorbs more carbon dioxide from the atmosphere, it becomes more acidic, negatively affecting marine creatures and altering marine food chains.

Increasing temperatures will potentially make New Zealand a more suitable habitat for invasive flora and fauna and disrupt migration and breeding patterns. Hawke’s Bay’s agricultural and horticultural businesses are particularly at risk.

The backbone of Hawke's Bay, our agricultural and horticultural industries will be challenged. Climate change impacts will see reduced river flows, increased water demand, higher risk of wildfires, soil erosion, extreme rainfall events and increased pest control problems. More frequent and intense droughts will influence pasture growth, livestock health, farm productivity, crop yields and reduced water availability for both irrigation and dry-farmed crops. The agricultural and horticultural industries will also be directly impacted by emergency events such as flooding or wild fires.

Businesses across Hawke's Bay will also be affected, the same impacts may affect manufacturing processes, geographical location, changing consumer or customer behaviours, the infrastructure businesses service, or simply changing business types around them. 

However, a changing climate may also provide opportunities. For example, new crop types previously unfeasible may be able to be grown in Hawke's Bay. 

How will Hawke’s Bay's climate change?

ClimatechangeTo help Hawke’s Bay prepare for the future, we asked NIWA to complete an assessment of climate change projections and impacts for Hawke’s Bay. This included rainfall, snow, droughts, temperature, wind and sea levels. Published in November 2020 it looks at all aspects of our climate to help us understand how it might change between now and 2100.

Access the full report here

You can read a summary of the main points of the report below.

Human Impact

Human activities drive the speed and level of greenhouse gas emissions across all aspects of society. To project climate-related impacts of rising greenhouse gas emissions, we need to estimate how much we will be able to mitigate, or reduce, our emissions and thereby minimise their effect on the climate.

To address this uncertainty, this technical report looks at different scenarios. For simplicity, we can say that these two scenarios are based on whether we reduce our worldwide emissions, or whether we continue emitting as we are today.  Within the report these internationally validated scenarios are referred to RCP 4.5 and RCP 8.5.

Summary of projections for Hawke’s Bay 

  • By 2040, annual mean temperatures across Hawke’s Bay are projected to increase by 0.5-1.0 deg C. If no mitigating actions are taken, inland western Hawke’s Bay areas may see further increases of 1-1.5 deg C during summer and autumn.
  • By 2090, projected annual mean temperature increases are 1.0-1.5 deg C where emissions reductions are taken, or could be up to 2.5-3.0 deg C where emission reductions are not taken, with inland, western areas potentially experiencing up to 4.0 deg C increase in summer averages.
  • By 2040, frost days in the eastern half of Hawke’s Bay are projected to decrease by 1-5 days, with inland, higher elevation levels projected to decrease 5-10 days, with or without emissions reductions.
  • By 2090, with emissions cuts, frost days in many locations are projected to decrease by 10-20 days, and without cuts, whilst much variation across Hawke’s Bay, higher elevations might see decreases in frost days of between 10-50.
  • By 2040, heatwave days are projected to increase by 10-20 days per year for much of the region, without emissions cuts, this will be much more widespread.
  • By 2090, projections are accentuated with cooler south-eastern areas of Hawke’s Bay also experiencing 10-20 heatwave days. Without emissions reductions, increases in some areas will reach 20-40 heatwave days per year.
  • Further studies into extreme heat in New Zealand also identify the Napier and East Coast area as having high and very high risks associated with extreme heat
  • The more significant changes are to seasonal rainfall patterns with an increasing number of extreme rainfall events being offset with longer dry periods. Overall, total annual rainfall levels will be similar.
  • By 2040, seasonal variation will see a 5-10% increase in winter rainfall, with a similar decrease in spring. Without emissions cuts, it is projected seasonal variations will be slightly larger and/or more widespread throughout Hawke’s Bay.
  • By 2090, without emission reductions, much stronger drying patterns are evident region-wide, with up to 15% increased rainfall in winter at high elevations.
  • Aligned to changing rainfall patterns, the region will see increasing drought frequency, especially for southern Hawke’s Bay due to increased potential evapotranspiration deficit.
  • Where emissions cuts are achieved, potential evapotranspiration deficits increase by 100-150mm, this becoming more widespread over time.
  • Without emissions cuts, potential evapotranspiration deficits increase by up to 200mm by 2090, with the probability for extreme events (+300mm) and droughts more frequent and much more wide reaching.

In coastal areas, sea-level rise is already affecting human activities and infrastructure, they leave us more vulnerable to storms and tsunami. Other impacts include: 

  • gradual inundation of low-lying marsh areas and adjoining dry land on spring high tides
  • escalation in frequency of coastal flooding events
  • exacerbated erosion of sand and gravel shorelines and unconsolidated cliffs
  • increased incursion of saltwater in lowland rivers and nearby ground water aquifers, potentially raising water tables

These will all have implications for existing development in coastal areas and associated infrastructure.

Since NIWA prepared this report however, further analysis has been completed on sea-level rise and vertical land movement showing that sea level rise may happen much faster due to vertical land movement. Much of Hawke’s Bay’s coastline is slowly subsiding, which further exacerbates the implications of sea-level rise. This information can be found here.

Additional information on the impact of climate change


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