2021-01-18 GC - Item 3 - Attachment 1 - Coastal Hazards Adaptation Plan for Community Consultation

         Developing this plan
This section discusses Phases 2 to Phase 7 of the CHAP’s development, including the methods
used to complete each phase, as well as their respective outputs.


Understanding climate change & sea level rise
The Earth’s atmosphere has warmed significantly over the past 200 years, and this is largely due
to human activities that have significantly increased the amount of greenhouse gases (GHG) in the
atmosphere. The rise in the concentration of greenhouse gases in the atmosphere is trapping more
heat within the Earth’s climate system than would otherwise have occurred without the increases in
these gases. This is in turn causing land and oceans to warm at a rate much faster than has
occurred naturally in the past3.

Based on the available science, the factor with the most influence on coastal hazards due to
climate change is rising sea levels. Sea level rise is the elevation of global and local mean sea
level caused by the expansion of the ocean as it warms, and the transfer of water currently stored
on land to the ocean, particularly from melting glaciers and ice sheets. Global sea levels are rising
at an increasingly higher rate than in the past 2000 years. Sea levels started rising at the 1800s
following the industrial revolution and as a result of increased dependency on fossil fuels. Between
1901 and 1990 the rate of global average sea level rise was 1.3-1.7mm annually, increasing to 1.8-
3.6 mm per year between 1993 and 2010 (IPCC 2014).

The result of this sea level rise is more land area exposed to coastal erosion and inundation
overtime.



Phase 2 – 3: Identifying the hazards
The first stage in developing a risk-based plan to respond to coastal hazards is to model and map
the expected behaviour of each hazard. Modelling of a range of scenarios was performed by
expert consultants, consistent with the QCoast2100 guidelines. The future climate scenario
modelling underpinning the hazard modelling is based upon a high global greenhouse gas
emissions scenario known as ‘RCP 8.5’ (often referred to as ‘business as usual’ because it broadly
represents an emissions pathway based on our current trajectory of minimal reduction) and a
projected rise in regional mean sea level of +0.8 meters by the year 21004. This scenario
represents minimal action being taken globally to reduce global greenhouse emissions between
now and the year 2100.

Noosa already experiences periodic tidal inundation and coastal erosion events. The first stage of
the project sought to understand how Noosa may be affected by changes in tidal water, storm
tides, and coastal erosion events due to rising sea levels. These events were modelled using
specialised software across four planning horizons – present day, 2040, 2070 and 2100.




3 https://climate.nasa.gov/evidence/
4 Intermediate projects for sea level rise are +0.2m by the year 2040, and +0.5m by the year 2070.


Noosa Council – Coastal Hazards Adaptation Plan 2020 - 2030 (community consultation version)         Page 11