Climate change risks
While K’gari and many of its World Heritage values are a consequence of past variations in climate and sea level, significant risks are associated with predicted future climate changes.
These risks could include:
- sea-level rise
- increased frequency of severe bushfires
- altered rainfall patterns
- increased severity of extreme weather events.
Sea-level rise
Projections of sea-level rise to the end of the century suggest the area around K’gari might experience between 60cm and 1m by 2100, and a sea-level benchmark of 80cm by 2100 has been adopted for state planning. This has implications for erosion of the sand shores and dunes.
Mapping the Queensland planning benchmark (80cm sea level rise with a storm tide estimate of 2m above the highest astronomical tide) shows there are areas of the island that are likely to be affected by storm tide and erosion in the future. In particular, the west coast of the island is particularly exposed to sea-level rise and its impacts. In addition, the west coast of K’gari is less exposed to ocean waves than the east coast, and therefore the west coast has experienced a smaller range of coastal sea level compared to the wave exposed east coast. This means the western coastline is not well adapted to larger sea levels making it more vulnerable to future sea levels that will occur outside the historical range.
It should be noted that higher impact low probability future sea-level rise (up to 1.6m) have been projected by expert judgment to include glacial ice melt. If these greater sea levels were to occur, they could result in greater coastal impacts.
We expect that long term sea-level rise will result in erosion and sea water inundation. Sea-level rise will considerably impact the low-lying areas along the western side of K’gari. Highly significant cultural sites, e.g. the Bogimbah Mission, are vulnerable to destruction.
Critically, sea- level rise will result in the re-activation of dunes on the eastern side of K’gari and, if the process continues, migration of sand into the centre and west of the island. This shift will, potentially impact rainforest areas (World Heritage criterion vii) and archaeological sites and heritage places located on dunes, in sand blows, and associated with coastal habitation generally.
Other risks
Climate change will also contribute to an increased frequency of severe bushfires on the island, particularly under drought conditions. This change may disrupt ecological processes and communities, notably rainforests, peatlands, and foredune vegetation. The change will also potentially have detrimental consequences on tangible and intangible Cultural heritage.
Fire has been an important driver of successional changes in vegetation on K’gari. Walker et al. (2022) report that on K’gari, fires tend to occur predominantly in the E. pilularis forests, with limited penetration in the Syncarpia hillii- and Lophostemon confertus-dominated forests. They point to the sharp fire transition boundary and changes in the understory vegetation and ground fuel as evidence of this, and the increasing dominance of rainforest species such as Syzygium spp. which regenerate in the absence of fire.
Recent years have seen several major fires on the island. In 2019, a fire burnt in the southern part of the island was followed by a major wildfire burnt for over seven weeks at the end of 2020. This second fire impacted more than half the island (approximately 80,000 ha). Walker at al. (2022) speculated that vegetation composition might change as a result of the 2020 fire. Ecological monitoring sites established by University Queensland and QPWS in 1995 based on the fire management strategy prepared for the island. Cultural burns hadn’t occurred for decades before the strategy and monitoring sites set up and vegetation transition was already underway due to this change in fire. Based on available fire history data since 1961, the average duration between two consecutive bushfires (bushfire return interval) between 1961 and 1991 for the study sites was approximately seven years and for the period of 1994 to 2020 was approximately 13 years.
Fuel loads and trends, as effected by climate, human activity and time since the last disturbance, also play a role in determining fire risk. An analysis of fires in Australia demonstrated an overall increase in area burnt, an increase in penetration of rainforest areas, a lengthening of the fire season into the cooler seasons. rapid decrease in the number of years since the last fire. The evidence suggesting that these trends will continue with climate change.
These changes, with altered rainfall patterns and an increased severity of extreme weather events, could impact the island’s World Heritage Outstanding Universal Value.
Threat assessment
The assessment of threats is outlined in the K’gari Conservation Outlook Assessment from 2014, 2017 and 2020. Reporting of Outlook Assessment has changed from every three years to every five years and the next report is due in 2025.
Results
| Threat | 2014 Status | 2014 Location | 2017 Status | 2017 Location | 2020 Status | 2020 Location |
|---|---|---|---|---|---|---|
Temperature extremes (Temperature changes) (climate change) | High threat | Inside site Outside site | High threat | Inside site, throughout (>50%) Outside site | High threat | Inside site, throughout (>50%) Outside site |
Minimising climate change risks
Climate change risk and vulnerability assessments and climate change adaptation plans have been developed for K'gari. They increase understanding of the potential impacts and will inform future management decisions.
In the short term, the climate change threat is considered ‘moderate’. However, as the effects of climate change become more pronounced over the medium to long term, the threat is predicted to move to ‘very high’.
