How will climate change affect us?

The evidence of climate change

(Image: Sonny Whitelaw)

Vanishing biodiversity

Summary

“Biodiversity in Aotearoa New Zealand, along with the rest of the world, is in a general state of crisis.Department of Conservation

“Wildlife populations plunged by 68% between 1970 and 2016, and only 25% of the planet can still be considered ‘wilderness’.World Wildlife Fund Living Planet Report 2020

“Restoring a third of the areas most degraded by humans and preserving remaining natural ecosystems would prevent 70% of projected extinctions of mammals, birds and amphibians. It would also sequester around 465 gigatonnes of CO2 — almost half of the total atmospheric CO2 increase since the Industrial Revolution.” – Strassburg et al, 2020.

  • Much of New Zealand’s biodiversity has already been lost (Fig. 1) or fragmented to the point where life supporting ecosystem services are failing.
  • Climate change is placing even more pressure on natural ecosystems, undermining their ability to help us mitigate the impacts and adapt to changes (Fig. 2).

“Climate change will affect terrestrial biodiversity through warming air temperatures, an increased intensity of severe weather events and rising sea levels. However, a thriving biodiversity can also be part of the solution, providing resilience to some of the predicted impacts of climate change.”  – Christie et al, Department of Conservation

Humanity stands at a crossroads with regard to the legacy it leaves to future generations. Biodiversity is declining at an unprecedented rate, and the pressures driving this decline are intensifying. None of the Aichi Biodiversity Targets will be fully met, in turn threatening the achievement of the Sustainable Development Goals and undermining efforts to address climate change. ”  – Global Biodiversity Outlook 5 (2020)

Fig. 1: What remains of New Zealand’s native forests. Other ecosystems including wetlands, dunelands, and braided rivers have suffered equally widespread net losses (i.e. the difference between losses and gains) of indigenous cover types between 1996 and 2018. For indigenous forests, scrub and shrublands, this loss was 40,800 ha, and for indigenous grasslands it was 44,800 ha. (p47 DOC1) (Image: DOC/Christie)
Fig. 2: How climate change will directly and indirectly impact bioidiversity (Image DOC/Christie)

The following is from the 2020 Department of Conservation report (pages 51-52) Biodiversity in Aotearoa: an overview of state, trends and pressures

Climate change | Te panoni āhuarangi

New Zealand’s biodiversity will come under increasing pressure as a result of global climate change (Christie et al. 2020). Pressures such as ecosystem fragmentation and pests will also likely be exacerbated (McGlone et al. 2010). It is difficult to know precisely how New Zealand’s biodiversity will respond to climate change in the long term. This is partly because the country’s climate is already highly variable, and partly because for land ecosystems many species and habitat types are now restricted in range as a result of vegetation clearance and the introduction of invasive pests (McGlone et al. 2010).

Some species and ecosystems will be more vulnerable to climate change than others (McGlone et al. 2010). For instance, the sex of a tuatara embryo is determined by the ambient temperature, so that warming will produce more males than females (Mitchell et al. 2010). Native peketua/frogs need moist conditions to survive (Newman et al. 2013), as do land snails (Walker 2003), and kiwi need soft ground to probe for worms (Cunningham & Castro 2011), so any changes resulting in a drier climate are likely to have impacts on those species. Similarly, kōura/freshwater crayfish have been shown to be highly sensitive to climate change, primarily because of their habitat specialisation (Hossain et al. 2018). In the freshwater environment, species such as alpine galaxias, which has a restricted distribution and is reliant on colder water temperatures, will be vulnerable to the warmer temperatures and drought associated with climate change (Boddy & McIntosh 2016). Intertidal marine creatures may be subjected to warmer air temperatures when the tides are out (Willis et al. 2007). Projected future increases in ocean temperatures are also expected to have large knock-on effects for the ocean food web and fish species (Law et al. 2017). The consequences for seabirds of changes in the Southern Ocean climate are still largely unclear (Barbraud et al. 2012). Climate change may cause shifts in the distribution of prey species and the flooding of low-lying colonies, while increased storminess may interfere with provisioning, foraging and fledging.

Some ecosystems will be particularly vulnerable to climate change. Particular examples are the susceptibility of marine ecosystems to warming temperatures and ocean acidification (Law et al. 2017); coastal ecosystems to sea level rise and storm surges (Bell et al. 2017); freshwater ecosystems to drought and flooding (MfE & Stats NZ 2018) and, indirectly, through increased human demand for water (Robertson et al. 2016). Increased demand for irrigation could deplete freshwater wetlands, streams and rivers, and allow saltwater to intrude into aquifers (McGlone & Walker 2011). Ocean acidification, warming oceans and sea level rise could have significant impacts on marine species (including seabirds) and the ecosystem services associated with them, such as food production (Lundquist et al. 2011, Pinkerton 2017; MPI 2019a). Meanwhile, alpine ecosystems will also experience changes with rising snow lines and temperatures (Hendrikx et al. 2012).

Climate change will also compound many existing threats. For now, the ranges of some animal pests (e.g. ship rats, hedgehogs and wasps) are partially constrained by cold temperatures, so they may expand – latitudinally and altitudinally – with warming temperatures (Christie 2014). These pests may survive in greater abundance, expanding their ranges upslope into higher alpine elevations than where they currently occur, creating a ‘thermal squeeze’ situation for native species. Invasive invertebrate species, which may not survive the winter season in Aotearoa at present, may at some point be able to persist (Ward et al. 2010; Lester et al. 2013; Lester & Beggs 2018). Similarly, some weeds and invasive pathogens (e.g. myrtle rust) could respond in a similar way (McGlone et al. 2010; Beresford et al. 2018). Fires will also likely start more frequently and burn for longer (Pearce et al. 2011), giving the advantage to fire-tolerant weeds (Perry et al. 2014). Taonga species important to Māori will also be vulnerable to the interacting drivers of climate change and pest invasion. Reductions in the ranges of taonga species and altered timing of biological events (e.g. flowering and fruiting) could impact on tikanga Māori. Furthermore, traditional mātauranga of environmental signals used for tikanga could be disrupted by climate change, and could affect the social fabric of whānau, hapū and iwi by compounding the loss of knowledge for rangatahi (King et al. 2013).

The human response to climate change may also bring further threats. Mass planting of exotic trees – while beneficial for carbon sequestration – could displace native vegetation, harbour weeds, alter water availability or heighten fire risk (Christie 2014).

The financial lure of exotic forestry

Of the many threats to biodiversity, the lure of planting commercial pine forests is potentially the most insidious because it financially incentivises a short term ‘solution’ to climate change through the NZ missions Trading Scheme (ETS). The current ETS does not factor in the full life-cycle cost of forestry: that is, carbon emissions from maintaining, harvesting, transporting, and converting plantation trees into wood products and/or shipping them to other countries.

Moreover, because it promises a financial income from carbon credits, particularly for farmers living on ‘marginal’ land, ie land that is not otherwise viewed as financially profitable, mass planting of exotic trees for carbon sequestration could further displace native vegetation, harbour weeds, alter water availability, and/or heighten fire risk.

“Exotic plants allow 2.5 times more carbon dioxide to be released from the soil compared to natives. Non-native plants interact differently with insects and soil microbes than native plants, which has dramatic consequences for carbon cycling. Many of New Zealand’s non-native plants grow faster than natives, which means they can store carbon more quickly. However, the same traits that allow faster growth also support microorganisms that return CO2 to the atmosphere at a faster rate.” – Waller et al.

While the co-benefits of essential life-supporting ecosystem services, carbon sequestration, and climate change adaptation capabilities of a healthy biodiversity are currently undervalued in the ETS, research is underway to rectify this situation:

“Through a series of discussions, interviews and workshops, the Biodiversity Domain of the Aotearoa Circle agreed that there is an opportunity to expand the role that businesses and government play in accelerating the regeneration of our native biodiversity, and this could be done through incentivising and scaling native planting across the country. Unfortunately, existing structures and mechanisms favour the planting of exotics species (Pinus radiata in particular) over New Zealand native species. Changes and further incentives are needed to reduce the feasibility and viability gap between exotics and natives, and ‘level the playing field’.”                – The Aoteaora Circle

Explainers

Ecosystems

Ecosystems are made up of communities of living organisms plus the physical and chemical environment in which they live. A healthy ecosystem is able to maintain the full range of the living organisms that normally inhabit that ecosystem, through ecosystem services that are provided by and for these organisms. The physical environment means the space they physically exist in to maintain healthy populations that are genetically diverse, and the conditions such as water availability and temperature. The chemical environment includes the ability to exchange life-supporting nutrients including oxygen, nitrogen, etc. and additionally in the oceans, salinity and PH.

See ‘ecosystem services‘ (this website) for more details.

References and further reading