Number of days over 35°C in the Cairns region
Figure 4. Number of days over 35°C under ‘Business as usual’ emissions scenario (MIROC5 climate model), http://www.climatechangeinaustralia.gov.au/en/climate-projections/explore-data/threshold-calculator/.
Sea level rise in Cairns
Figure 5. Increased height (in metres) needed to maintain the current level of exposure of assets to flooding from high tides & storm surges, under ‘Business as usual’ emissions scenario, http://www.climatechangeinaustralia.gov.au/en/climate-projections/coastal-marine/marine-explorer/.
People in the Daintree Local Landscape know that rainfall, temperature and cyclones vary from year to year, but that our ability to live in and manage the landscape is based on long experience of general seasonal patterns. However, knowledge based on past experience is becoming less reliable as temperatures and sea levels rise and extreme weather events become more common. The science is telling us:
- Less predictable weather: While there is always some natural variation in local weather patterns, climate change will make it increasingly difficult to rely on our past experience to make decisions affecting our lifestyles and landscapes, including access to the Daintree area, protection of people from extreme weather events and land management.
- Climate change and industries: Agricultural enterprises, as well as tourism, in this Local Landscape will experience changes and challenges as a result of climate change. It's important we are aware of likely changes to enable planning to ensure a strong economic future for the Daintree.
- Climate change and communities: The effect of hotter temperatures, sea level rises and more extreme weather events will impact on people living in the Daintree. Knowing about the types of changes likely to occur will mean we aren't taken by surprise by unusual climate events.
- Climate change and natural systems: The Daintree's high biodiversity values will be affected by climate change, but the area is likely to remain a hotspot for plants and animals. There will, however, be complex management implications for natural resource managers to increase the resilience of natural systems.
There are opportunities for everyone to get involved in shaping a resilient and sustainable future for the Daintree. For more information on climate change, including links to more detailed climate change modelling for our region, go to the Climate Futures page.
Long term temperature records from the Low Isles Lighthouse weather station show that average temperatures have generally been on an increasing trend over the past 30 years. During this time, average annual temperatures in the Daintree region have been above the long-term average much more often than they have been below it (Figure 1).
Long-term rainfall data from the Cape Tribulation store shows that rainfall continues to vary dramatically between years, and that there is no obvious increasing or decreasing trend in annual rainfall at this stage (Figure 2).
As time goes on, higher temperatures will be reached more frequently. For example, maximum daily temperatures during January are projected to increase from the current average of 32.3°C to 33.8°C by 2030, 33.9°C by 2070 and 35.2°C by 2090 (Figure 3). Furthermore, there will be a longer season of high temperatures, with average daily maximum temperature exceeding 30°C from September to April by 2090.
While we are likely to see an increasing trend in temperatures as a result of climate change, one of the most concerning predictions coming from climate scientists is the impact of greater variability and less predictability in our weather patterns, making it harder to plan.
There is a lack of official long-term temperature records in the Daintree local landscape region, with the closest official temperature measurements from Low Isles, and the nearest official mainland temperature measurement at the Cairns airport. Sharing reliable information collected by residents of the Daintree region would help people keep track of how the local climate is changing and could also be a way of recording and sharing observations about the survival, growth, reproduction, health and so on of native and pest plants and animals. Having access to this local information will make it easier to discuss changes and try possible management responses.
Tourism in the area is underpinned by the natural values of the coast and mainland forest areas. Climate-induced changes in the health and composition of natural systems, including the potential loss of iconic species (see below), will potentially have major impacts on tourism in the area. The Daintree region is likely to remain an important destination for the tourism industry, although access to the area and supplies of food, energy and other materials will also be impacted by sea level rise, more intense cyclones and more frequent and intense heavy rainfall. Since tourism is already very seasonal, prolonged hot weather and less predictable rainfall is likely to affect visitation patterns, while more extreme weather may influence tourists’ perception of their safety in the region.
Climate change will also impact the commercial fishing industry. For example, intense cyclones can cause several months of lost operations due to large amounts of debris or sediment in the water and damage to boats, marinas, ramps and other infrastructure. Commercial fishing operations will be affected as certain types of fish move south due to increasing water temperatures, as coral bleaching becomes more widespread and as conditions decline in fish breeding and nursery areas.
In the Daintree region, grazing and cropping will be directly affected by increasing average temperatures, evaporation, heat waves, seal level rise and extreme rainfall. Climate change impacts will also affect forestry timber production, changing patterns of growth in different timber species, and increasing damage and loss during high intensity cyclones. Agriculture in low-lying coastal areas will obviously also be vulnerable to sea level rise and climate change may also bring new diseases and pests, which we know potentially pose enormous threats to our agricultural industries. Flooding associated with extreme rainfall will also affect waterways and floodplains, potentially increasing erosion in these areas.
Changing climatic conditions will challenge our established ways of doing things, but may also present new agricultural and commercial opportunities. For example, it may be necessary to diversify or switch crops or breeds to suit new climatic conditions, or to change practices. In order to adapt to new and changing climatic conditions, we may need to shift farming and other commercial enterprises to different parts of the landscape. This could create opportunities for the restoration of wildlife habitat on former agricultural land, but could also create conflict between the need to protect existing habitat and also maintain production.
Doing things the way they’ve been done for generations won’t necessarily keep working as climate conditions continue to change, meaning that traditions and local wisdom will be challenged. Everyone will be affected in one way or another by climate change: some types of farms may not remain viable, certain areas along the coastline may become unsafe to live, and some of our iconic species may not survive in the new conditions. While change can be unsettling, new opportunities may come out of new ways of doing things, especially by working together across sectors and industries. Importantly, being informed about the types of changes we can reasonably expect means that we can develop plans and strategies to adapt to these, rather than being taken by surprise by unusual climate events.
Although people in the Daintree area are used to living with high temperatures, we can expect that periods of extreme heat will become more common and even hotter. For example, the number of days hotter than 35°C in the Cairns region is projected to increase from the current average of four to 11 by the year 2030 (and to 18 by 2050) under the ‘business as usual’ emissions scenario (Figure 4). More people will be vulnerable to heat-related illnesses and stress, especially sick, elderly and very young people, and people living without air-conditioning.
In the same way that maximum temperatures are increasing (Figure 3), minimum temperatures are also rising. This means that overnight temperatures will remain above 20°C for more months of the year, potentially affecting sleep quality, especially for households without air conditioning, and increasing the use of air conditioning in households with it.
Sea levels are already rising and models project that sea levels in this region will increase by an average of 0.14 m by the year 2030, and by an average of 0.65m by 2090 under a business as usual emissions scenario. By 2030, homes and other assets in low lying coastal areas will need to be 0.14 m higher (and by 0.79m in 2090) to maintain their current level of exposure to flooding from the ocean (Figure 5). Low elevation areas of the coastline will be most vulnerable.
Rising sea levels will increase the tidal extent of coastal rivers and streams, meaning that the tidal reach in the Daintree River for example may push further upstream of Barrett Ck, potentially affecting access to the Daintree village and the ability to intake water from coastal streams for reticulated or independent water supplies. Even a modest increase in sea level height will mean that there are many more high tides and storm surges, increasing coastal erosion, flooding and contaminating freshwater systems with salt water. The CoastAdapt tool (https://coastadapt.com.au/) helps people making decisions in coastal areas to understand and asses the risks posed by climate change in their regions.
The impacts of sea level rise will be compounded by more frequent and intense heavy rainfall events in the region, as well as more intense (though probably less frequent) tropical cyclones. There will be an increased threat to homes and roads in low-lying areas and along the Daintree coastline from river flooding and storm surge and cyclonic winds. This will exacerbate the current situation where road access and ferry travel in the area are already regularly impacted by flooding. The damage caused to roads will also likely be greater, meaning that they remain impassable for longer and cost more to repair. Residents in this already-isolated region would be even less mobile, and travel in and out of the area may become more dependent on air and sea transport.
Local planning for development, stormwater drains, roads and bridges will be affected. For example, more intense and frequent heavy rainfall events will increase the risk that sewerage and water treatment plants will be inundated, and will increase the potential for water supplies to become contaminated in communities such as Wujal Wujal. In addition to flood risk, there is an increased potential for soil erosion and land slippage, especially on steep slopes. We can expect more frequent interruptions to grid-based electricity supply with consequences for households, as well as the operation of municipal services such as water supply. In addition, shut-down of the region’s rail lines, sea and air ports during extreme weather events will affect fuel and other supplies in the Daintree region. Working together to address back-up power and supply issues will help build the Daintree region’s resilience in the face of these changes.
Various programs are available to assist with developing and implementing adaptation strategies (for example, the QCoast2100 program for local governments to develop Coastal Hazard Adaptation Strategies http://www.qcoast2100.com.au/).
Natural systems have coped with changing climatic conditions in the past but current changes are happening so fast that some species may not be able to adapt. Because climatic factors such as temperature and rainfall play such an important role in determining the suitability of different areas for plants and animals, we can expect that changes in temperature and rainfall will change the suitability of the landscape for certain species and systems. The result of climate change will be new combinations of plants and animals, sometimes in new locations, challenging our concept of what is ‘natural’. It’s also likely that this region will become more attractive to people moving from other areas that become less liveable. Increasing pressure for housing and more infrastructure to support growing populations will potentially lead a push for more clearing of native vegetation.
The Daintree local landscape area is likely to remain a biodiversity hotspot area into the future, supporting unique and complex communities of plants and animals. However, climate change will alter the nature of this iconic area, meaning that some animals and plants may no longer be able to survive or reproduce here. For example, habitat for cassowaries will be impacted by sea level rise, with the loss of coastal freshwater wetlands, and by changes in the fruiting patterns of plants resulting from warmer temperatures and changed rainfall. Modelling shows that coastal areas will rapidly become less suitable for cassowaries over the next two decades. Under a business as usual scenario of greenhouse gas emissions, suitable climatic conditions will continue to decline across the coastal and subcoastal lowlands, with some areas, e.g., around Cape Tribulation, projected to become unsuitable by mid-century. In these models, suitable climate for cassowaries will contract to the elevated ranges (http://climas.hpc.jcu.edu.au/maps/). In reality, changes may not unfold exactly as these models project, but these projections have complex implications for how we manage landscapes to protect our plants and animals; we have to protect areas that are currently important so that threatened species survive, but also consider where important habitat will likely be in the future, together with whether and how plants and animals would be able to move there and establish. These considerations affect our decisions about which areas to protect and restore, as well as how to manage these areas.
Coastal species in particular are at risk from sea level rise, for example as beaches are inundated and freshwater wetlands and coastal scrub transition to salt-tolerant vegetation communities. Critically endangered littoral rainforest systems are under extreme threat from climate change. These natural systems protect a diversity of threatened plants and animals, as well as protecting coastal settlements. Sea level rise will mean that there will be fewer nesting beaches for sea turtles, and a range of birds and mammals will be affected by the loss of freshwater wetlands as beaches and dune systems are inundated or eroded. Freshwater wetlands and coastal floodplains, together with the abundant wildlife they support, are also under threat from more intense flooding during heavy rainfall events and salt water contamination due to sea level rise and storm surge. We can also expect widespread dieback of sea grasses and mangroves in lower intertidal zones, due to sea level rise, more intense cyclones and storm surges. These impacts will have a range of flow-on consequences for fish, dugong and other estuarine and marine life. Strategies such as the planned retreat of human settlements and infrastructure from coastal areas may reduce the risk to humans and also create opportunities for natural systems to shift.
In addition to the direct effects of increased temperatures and changed rainfall, climate change will have a range of indirect effects on other factors that drive natural systems. A major impact of climate change for natural systems will be more frequent and/or more intense disturbances, such as floods, heatwaves and cyclones. For example, increased intensity and frequency of river flooding, together with increased water temperatures, will change aquatic systems, as well as those fringing waterways or on floodplains. Narrow riparian vegetation will be particularly vulnerable. More extreme rainfall events will also increase the frequency of intense disturbance to in-stream invertebrates, animals and plants, and exacerbate the issue of soil and pollutant runoff entering the Great Barrier Reef lagoon. On a national scale, the Bloomfield and Daintree Rivers are among a small number of watercourses identified as being priorities for conservation of freshwater biodiversity under climate change.
Prospects are bleak for the Great Barrier Reef under a business as usual scenario of climate change. Bleaching of coral reefs will continue to be more widespread as average temperatures increase and heatwaves become hotter and more common. As hot spells occur more frequently, reefs won’t have time to recover from previous bleaching episodes and will eventually collapse. Reef systems will also be affected by more acidic sea water (caused by higher CO2), more intense cyclones and freshwater pulses associated with heavy rainfall events.
Managers of biodiversity are already working to minimise or reverse impacts of land clearing, pollution, introduced plants, animals and diseases on natural systems. Climate change is an additional impact that interacts with these existing pressures. The resilience of natural systems to cyclones and other disturbances is improved by having a large and well-managed network of protected areas. It’s not possible to predict the exact consequences of climate change for plants, animals and their habitats, but sharing observations, trying new management practices and monitoring their outcomes will help build the new knowledge required to promote adaptation of natural systems to climate change.