What does climate change mean for our national parks?
Sweeping gold sand beaches, mighty snow-capped peaks and valleys carpeted in lush native forest: New Zealands national parks contain some of the countrys most spectacular landscapes, memorable outdoor pursuits, and vulnerable native species. But all 13 parks, covering nearly 2.9 million hectares almost 10 per cent of New Zealand will be affected by climate change. Sea level rise and more frequent high-intensity storms are expected to damage infrastructure like tracks and huts, while temperature increases and a rising snowline will shrink the habitat of threatened species and allow predators and pest plants to spread higher into alpine zones. Fortunately, these changes are not happening overnight and theres time to adapt but it needs to start now. READ MORE: * More rats, hungry Kiwi: How DOC plans to prepare native species for climate change * Fiordland track repairs vital to rebuilding the 'walking capital' of New Zealand * Rain wipes out alpine tracks at Aoraki/Mt Cook National Park The Department of Conservations (DOC) climate change plan says climate change already affects every aspect of its work. Climate change adaption programme leader Sam Parsons, one of four lead authors of the plan, says the document sets out a roadmap for where DOC needs to focus its climate change research and how it will prioritise and assess risk. That information will be used to create plans that provide several ways of moving forward, but can switch between branches if certain thresholds or triggers are reached. Parsons says this approach deals with the uncertainty of when some of these climate change effects will occur, given that what people do now will have an impact on how badly the climate changes. It is also the most cost-effective way to approach the problem, as DOC will not be removing assets that are still functional or pouring extra resources into protecting species until they are at risk. We want to be really proactive in our planning, so were not being reactive, and were not losing species or recreational experiences first and then adapting," Parsons says. We know our pressures and when we start to see those signals and those triggers coming down the pipeline, then were implementing the right decisions at the right time to keep these things safe. In early February, Fiordland National Park New Zealands largest was badly affected by extreme rainfall. These types of storms are forecast to happen much more often in the coming decades. DOC lost about 440 kilometres of track, two huts, a handful of bridges and about 500 traps (20 per cent of the parks trap network) to the flooding. Repairing the damaged tracks will cost $13.7 million . In 24 hours from midnight February 3, Milford Sound received 566 millimetres of rain more than it normally gets the entire month. From February 1 to 4, there was more than 1120mm of rain. Niwa estimated the peak one-day rainfall would happen once every 86 years, while the storm as a whole was a one-in-170 year event. But, by 2040, projections predict storms like February's will happen once every 120 years, and become a one-in-59-year event by 2090. February's peak one-day rainfall will be a one-in-55-year event by 2040 and can be expected every 27 years by 2090. "When were dealing with those high intensity events, thats what going to lead to a lot of disruption, a lot of loss, and place our biodiversity and our visitors at a lot of risk, says Parsons. He says climate change is expected to increase the intensity of heavy rainfall events nationwide. But the West Coast and Southland will be most affected, because of the high rainfall those areas already get. If you add on 30 per cent then suddenly youre dealing with a huge quantity of water. Parsons says DOC already has the tools and methods to build in these kinds of environments, but using future projections can guide its planning. We just cant use that historic data that weve used to inform our thinking previously, we need to start building for the future climate that these structures are going to be in. On the slopes of alpine areas like Aoraki/Mt Cook National Park, climate change is going to cause a "real estate crisis that will affect both recreational visitors and native species. The decline of glaciers has been well-documented: over the four decades New Zealands glaciers have been surveyed , they have lost a third of their ice . From March 2016 to March 2019, Brewster Glacier in nearby Mt Aspiring National Park lost an estimated 13 million cubic metres of water enough to supply drinking water to all New Zealanders over that time. Parsons says Aoraki is projected to have significantly more dry days and hot days as the climate warms. He says one of the more concerning projections, if the world continues to produce high greenhouse gas emissions, is that there would be 30 to 60 fewer frost nights per year by 2090. One or two months of not having a frost combined with far warmer temperatures... you can guess what's going to happen to that snowline and that permanent ice. Parsons says in alpine areas such as Aoraki, which have highly localised species like Mt Cook lily and rock wren, and are used by mountaineers and hikers, there is going to be a real estate crisis when that habitat starts to shrink and there is nowhere to go, because there is a top to every mountain. Alpine areas currently make up about 30 per cent of the conservation estate. Rising temperatures and snow lines also mean predators will be able to move higher into alpine areas in the future. Species like rock wren and kea that nest on the ground, rock wren aren't great fliers, theyre pretty easy prey for those invasive predators, so its something that we need to be really aware of going forward in terms of where were planning our predator control and how intense were getting in that alpine zone, Parsons says. Predators like rats and stoats are already moving higher into alpine zones, and are surviving through winters that would have once killed them off in large numbers. Exactly what impact these predators will have on alpine species is not yet known. A recent study found stoats in alpine areas of the South Island preferred eating small mammals , especially ship rats, but would turn to insects and lizards when they had to, and ate fewer birds than expected. Other research found alpine birds like rock wren were heavily affected by stoats. Tongariro National Park is also going to face a real estate squeeze, but , unlike Aoraki, it does not sit in a range of mountains that could give flora and fauna a potential pathway to retreat along. Another concern is that the red tussock blanketing Mt Tongariro could be replaced with the pink flowers of the invasive weed European heather as the climate changes and the plant is already creeping further up the mountains. The heather was introduced to the park about 1910 as a potential habitat for game birds like pheasants and grouse. Though the birds were never released, the heather was. Parsons says the native grasses, shrubs and other alpine plants being squeezed out by the heather support all the biodiversity in Tongariros alpine zone, and are part of the same food cycle. So when you have something like European heather that can come in and grow in really high densities, it starts to become quite a monoculture and same with the wilding conifers where they just creep uphill, uphill and push out all that biodiversity. It's the risk of losing a highly diverse environment towards a real monoculture environment. Modelling by researchers at Victoria University of Wellington predicted that, by 2070, there would be an eleven-fold decrease in the land area in the park that is not affected by heather , reducing habitat for native species. To try to manage the spread, DOCs next steps are to fill in the information gaps it has on the weed, so its operations team can adapt their current weed control programmes In a lot of instances it's not going to be this wholesale change on how DOCs operating in the area, its just going to inform where they need to be focusing on, Parsons says. Of all the ways climate change will affect New Zealands national parks, sea level rise may be the best understood. In 2019, DOC and the Niwa mapped out which DOC sites, huts, tracks and other assets were at risk from the rising ocean, based on an expected half-metre to a metre of sea level rise by the end of the century. Of the countrys 13 national parks, Abel Tasman will be most impacted by the rising sea . About 4.2 kilometres of the popular coastal track and 62 assets such as huts and campsites could be vulnerable. The park is a hugely popular tourist destination, getting about 300,000 annual visitors to the coastal track before coronavirus put the clamps on international tourism. Tropical storms in February 2018 have already shown how vulnerable the coastal track is to the ocean , causing hundreds of thousands of dollars of damage and jump-starting the process of moving campsites further away from the beaches. The Tonga Quarry campsite, which was on a sandspit, was deemed too exposed for safe camping and was closed, while the campsite at Bark Bay will be moved to higher ground in the near future. But DOC can stage a managed retreat from the rising tide, and has some advantages that coastal communities do not enjoy. Because they manage the land further inland of their vulnerable assets, they are free to move back as they see fit without worrying about Parsons says he is confident the retreat in the park can be done really well, and will still retain the coastal experience it is known for.