Climate change: Are Australia's wildfires New Zealand's future?
Parts of New Zealand may in future experience weather conditions similar to those that led to devastating wildfires in Australia, with the entire country facing longer, more dangerous fire seasons, a new study shows. The study from forestry research group Scion - called Adapting and mitigating wildfire risk due to climate change collected data through a climate model that covered the entire country in 5km by 5km grids to give a more accurate picture than previous studies. According to Grant Pearce, scientist for fire research at Scion, a combination of increases in temperature, decrease in rainfall in some areas, and increasing winds tended to lead to more frequent fire weather days. Fire seasons were expected to become longer, starting earlier in spring and extending longer into autumn. READ MORE: * New Zealand's luck will run out if it does not prioritise land sustainability * Covid-19: 'Ute tax' delayed until April as a result of Delta outbreak * Department of Conservation appealing controversial Far North water consents * Turning our roofs into a weapon to fight climate change Because New Zealand has different terrain types we have a large number of microclimates and many of the effects of climate change will be localised. Increases or decreases in rainfall is a key factor in this variability, Pearce says. The research included four possible future scenarios up to the year 2100 that try to quantify fire danger based on how the world tackles climate change in future. A first scenario could play out if the world removed carbon dioxide from the atmosphere, another two explored scenarios where CO2 emissions remained relatively stable, and a final scenario projected fire danger in a world with high greenhouse gas emissions. The first scenario showed possible recovery of wildfire trends by 2100. The next two would see wildfire risk increases of less than 5 per cent on average per decade, with the South Island showing more increases than the North Island. A future with high greenhouse gas emissions could mean wildfire risk increases of on average 10 per cent per decade. On average, fire risk will increase, both in season length of fire weather conditions and the intensity of fires that may take hold, until mid-century regardless of climate mitigation efforts. The study showed for the first time that conditions that led to the devastating Black Summer fires in Australia would occur every three to 20 years in areas of the Mackenzie Country, Central Otago and Marlborough. Pearce says a broader understanding of all conditions that lead to fires was necessary to enhance preparedness. The Ohau fires in 2020 that burned over 5000ha was a prime example. The Ohau fires were at a time of year one would consider as low fire risk. But there was a lot of dead grass from frost curing and very strong winds. It is often a combination of two or three factors that lead to significant fires, he said. More homes were destroyed during the 2016-2017 fire season than had been in any of the previous 100 years. This was surpassed in 2020-2021 when the Ohau fires destroyed 48 houses, the report said. That was an indication that changes in fire seasons were already occurring, Pearce said. The recent study showed that especially rural-urban interfaces, where urban developments were next to or intermixed with rural vegetation, had a higher fire risk. There was more that could be done in the urban planning space and where and how development should occur must be considered, Pearce said. A concerning trend in recent years was that forests grown for carbon capture purposes were not managed in the same way that forests grown for timber were, with fire controlling measures like thinning of undergrowth for example not being standard practice, Pearce said. Discussions with the government around managing carbon forestry are under way. We want to understand the practices associated with carbon forests, Pearce said. Some of them arent managed at all. They may still need fire breaks or have water sources put in place in case helicopters or fire trucks need it. Areas prone to severe fire weather danger should maybe not be planted with unmanaged forest. Native forests were less flammable than introduced species plantations but with increased fire danger it was expected that natives could also burn more frequently. Scion had recently secured government funding for research on the fire behaviour of indigenous forest. A range of species are present in native forests. Their characteristics need to be understood to develop mitigation of increased risk, Pearce said. The study showed an increase in areas projected to experience significant numbers of days each fire season that could produce severe fire behaviour. Large areas of the South Island in particular were predicted to see more than 40 days per season of highly vigorous surface fires by 2080-2099. Farmers in general are more aware than the general public of the risks of fire, particularly hill and high country farmers that use fire for prescribed burning. They should be more aware in future when they undertake such activities, Pearce says. Tim Mitchell, national wildfire manager for Fire and Emergency, said that a lot of work to mitigate risks needed to be done by communities. To get a wildfire two things are needed. The environment has to be suitable for a wildfire and an ignition source is needed, Mitchell said. Most wildfires are caused in some way by human activity. Just because it is warmer and drier doesn't necessarily mean we will have more fires. People need to modify their behaviour and think more about fire risk. Communities needed to do mitigations to reduce ignition potential and could clear vegetation around properties or put thought into the type of vegetation they plant. They also need to think about activities, like camping or riding motorbikes in dry areas, at times when there is high fire risk. We are working with international agencies in countries that handle significant wildfires to understand how we can offset risks, Mitchell said.