Number of days over 350C in Mareeba
Figure 4. Number of days over 350C under 'Business as usual' emissions scenario (MIROC5 climate model) http://www.climatechangeinaustralia.gov.au/en/climate-projections/explore-data/threshold-calculator/.
People in the Northern Tablelands 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: We have already observed increases in temperature in our Local Landscape, particularly in more recent years. Changes are likely to continue, making it increasingly difficult to rely on our past experience to make decisions about where to build houses and infrastructure, which crops to grow, which pests and diseases to target, and how to manage fire.
- Climate change and industries: While climate change will have impacts on our local industries, including grazing, cropping, horticulture and tourism, the Northern Tablelands is well-placed to research and develop new industries or practices to ensure we maintain a strong economic base for our region.
- Climate change and communities: Climate change will affect all of us and will have serious implications for the health of our communities. Working together cooperatively and accessing reliable information will allow us to plan and prepare so our healthy and vibrant communities continue to thrive.
- Climate change and natural systems: The rate of change in climatic conditions already being observed in our region will make it difficult for our natural systems, plants and animals to adapt. While the exact consequences of climate change can be difficult to predict, we have good information available now which we can use to help prepare and build resilience in our natural systems.
There are opportunities for everyone to get involved in shaping a resilient and sustainable future for the Northern Tablelands. 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 data from Walkamin shows that average temperatures have been on an increasing trend over about the past 20 years, and that during this time, average annual temperatures in the Northern Tablelands region have been above the long-term average much more often than they have been below it (Figure 1).
Long-term rainfall data from Walkamin show that rainfall continues to vary dramatically between years, and that there is no obvious increasing or decreasing trend (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 around 30°C to 31.5°C by 2030, 31.6°C by 2070 and 32.9°C by 2090 (Figure 3). Furthermore, there will be a longer season of high temperatures, with average daily maximum temperatures exceeding 30°C from October to March by 2090, rather than from November to January as is currently the case.
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.
Northern Tablelands beef grazing, cropping and horticulture enterprises are directly dependent on natural resources and climate conditions. Increasing average temperatures, evapotranspiration, heat waves, extreme rainfall events and increasing atmospheric carbon dioxide will substantially affect these industries. For example, yields of many crops, including corn and maize, decline when temperatures are hot. As time goes on, higher temperatures will be reached more frequently as both average and extreme temperatures increase (see above). The many tree crops grown on the Northern Tablelands - banana, avocado, citrus, coffee, custard apple, longan, lychee, mango and paw paw - are very susceptible to damage during intense cyclones. Increases in evaporation from irrigation channels that supply critical water from Tinaroo Dam will also affect these crops. 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.
The Northern Tablelands landscape is likely to remain an important food production area, especially for the north Queensland region. With higher costs of long-distance transport based on fossil fuels, the cost advantage to local markets of regionally-produced food will be likely to further increase, although the economic viability of supplying distant markets may decline and costs of inputs may increase. Regional primary industries may also be impacted by increasing bottlenecks in processing or distribution networks. For example, heat waves, cyclones and floods all have the potential to result in shut down of facilities such as the Cairns sea and air ports and regional rail lines, potentially interrupting both the import of fuel, food and other supplies, as well as the export of regional produce.
Tourism in the area is underpinned by the natural values of the region. 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. Since tourism is already very seasonal, prolonged hot weather and less predictable rainfall is likely to affect visitation patterns to the region, while more extreme weather may influence tourists’ perception of their safety in the region.
The mining industry is particularly vulnerable to climate change impacts, since operations can be interrupted by heatwaves and floods, both of which are projected to be more frequent, as well as by cyclones. Mining industries also depend on supply and distribution systems that are susceptible to interruption by these types of events.
In addition to providing water for irrigation, Tinaroo Falls Dam supplies drinking water to many settlements on the Northern Tablelands and Cairns. Increasing rates of evaporation from the Dam and irrigation channels will potentially reduce the supply of freshwater to the Northern Tablelands, especially if rainfall declines. At the same time as the availability of water may decline, higher temperatures and rates of evapotranspiration from plants will increase the amount of water needed for primary production. In addition to options such as covering channels and installing new farm dams that minimise evaporative losses, producers may consider changing to crops with lower water needs. Any increasing population trends in the supply regions will also create more demand for water from the dam.
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.
In order to develop industries that are adapted to the new climate conditions, it will be critical to base decisions on current information about local climate patterns together with data on the responses of crops and stock to these changes. The Northern Tablelands already supports a diverse agricultural sector and has the enviable potential for local agricultural research and development at the Walkamin Research Station. In addition to research into irrigated agriculture, the station also retains facilities for research into freshwater and aquaculture industries and has the potential to work with producers in the region to trial new options for crops and farming systems.
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 Northern Tablelands 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 Mareeba is projected to increase from the current average of five to 13 by the year 2030 (and to 20 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.
Fire weather is likely to increase in the Northern Tablelands landscape due to the combination of increased evaporation, higher average temperatures, and more frequent and hotter heatwaves. For example, evaporation is projected to increase on average by around 4% annually in north Queensland. Increases in some months are expected to be higher (e.g. 7% increase in January, projections from climate model Had GEM2-ES). While fire is already a familiar part of this drier end of the Tablelands, these conditions would be likely to promote more intense, frequent, and extensive bushfires. If elevated levels of CO2 promote the growth of native C4 grasses such as blady grass Imperata cylindrica, this will exacerbate the risk of large, hot fires in the Northern Tablelands.
We can expect that heavy rainfall events will become more frequent and intense, potentially increasing the occurrence and severity of flooding in the Northern Tablelands region. Areas around Mareeba & Biboohra are likely to be most vulnerable, as homes, businesses and roads are already subject to extreme risk from river flooding. Planning for infrastructure such as stormwater drains, roads and bridges will need to account for projected worsening of flooding.
With rising temperatures, some of the features of the Northern Tablelands that currently set it apart from other parts of the region are also likely to change. For example, climatic conditions are expected to become more suitable for mosquitoes, meaning that dengue fever is likely to become more common on the Tablelands rather than being restricted to the coast. Presently, coastal areas tend to bear the worst impacts of tropical cyclones, but cyclone damage on the Northern Tablelands is likely to be more extensive as cyclones become more intense (though probably less frequent), and therefore retain more energy when they reach the Tablelands. The impacts of sea level rise in coastal parts of our region will be compounded by more frequent and intense heavy rainfall events, as well as more intense tropical cyclones. While this will not directly impact the Tablelands, we can expect more frequent interruptions to fuel and other supplies due to shut down of the region’s rail lines, sea and air ports during extreme weather events. Working together to address back-up power and supply issues will help build resilience in the face of these changes.
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 Northern Tablelands are likely to retain climate conditions that suit many of the species that are currently found here. However, some animals and plants may no longer be able to survive or reproduce in the area. For example, parts of the Northern Tablelands, such as the Lamb Range, are currently the stronghold for the endangered northern bettong. Northern bettongs depend on complex relationships between truffles (fungi), trees and fire, and climate change may well alter these relationships. Modelling projects a rapid decline in the climatic suitability of these areas within the coming decade (http://climas.hpc.jcu.edu.au/maps/). Under a business as usual scenario of greenhouse gas emissions, suitable climatic conditions are projected to continue to decline and to be lost from across most of the bettong’s current range within the Northern Tablelands by the year 2085. 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 factors such as fire in these areas.
In addition to the direct effects of increased temperature 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, fires, 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. 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.
Fire conditions are likely to alter in unpredictable ways, depending on how rainfall patterns change, how grasses and other plants respond to increasing carbon dioxide in the atmosphere, and how these things interact with increased temperatures and more frequent heat waves. It is likely that managers will need to change practices to implement fires that benefit a range of species and maintain grasses in open forest and woodland systems.
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.