This module provides an introduction to various aspects of climate change in estuaries. The module addresses the following questions:

• Why assess climate change risk in estuaries?
• How do estuaries function?
• What are the main types of estuaries in NSW?
• How does climate change affect estuaries?

Download Module 1: "Climate change in estuaries - State of the science & guideline for assessment, opens in a new window"

Prioritising changes in the climate and ocean systems

This module provides guidance on estimating the potential changes in climate and ocean boundary conditions that will be faced by estuaries in the near and far future. It presents an introduction to climate change and climate science along with methods for prioritising changes based on climate projection data. This module addresses the following questions:

• What is climate change and what are the main causes?
• What are climate models and emission scenarios and how are they used to project the future climate?
• How can changes in the climate be prioritised based on their relevance for estuaries?
• What are the key climatic changes faced by estuaries now and in the future?

Assessing climate change in estuaries requires a robust understanding of how projections of future climate are generated and how the severity of change can be derived from these projections. This guide uses climate projections from the New South Wales and Australian Capital Territory Regional Climate Modelling (NARCliM) project, and illustrates how statistics and extreme indices can be applied to prioritise change in the climate system based on their deviation from historic variability envelopes.

Download Module 2: "Prioritising climatic changes, opens in a new window"

Determining the physical response of estuaries to changes in the climate and ocean boundary conditions

Module-2 introduced methods for estimating likely changes in the climate and ocean boundary conditions of estuaries (i.e. rainfall and sea level rise). However, estuaries are highly dynamic and complex systems and each estuary will have a unique physical response to these changes, depending on its geomorphologic regime and hydrologic setting.

Estimating the likely physical and chemical response of estuaries to changes in the climate and ocean system often requires some form of modelling. Module-3 provides an overview of available modelling approaches, their respective data requirements as well as their advantages and disadvantages. It also provides a conceptual model that can be used to generate a first-pass estimate of the physical response of estuaries to different climatic stressors.

Module-3 addresses the following questions:

• What are the available modelling approaches?
• What are the available data sets?
• What is the likely response of different types of estuaries to different climatic stressors?
• How can changes in the climate be prioritised based on their relevance for estuaries?
• What are the key changes in climate faced by estuaries in NSW?

Download Module 3: "Physical responses to climate change, opens in a new window"

Assessing the impacts of climate change to estuary ecosystems

In a climate change risk assessment, an estimate of likely changes in the physical and chemical estuarine environment is typically followed by an assessment of estuarine ecohealth. Module-4 provides an overview of the ecological significance of estuaries and their most abundant ecological communities. The Module summarises likely ecological responses of ecological communities to climate change stressors and provides a qualitative rating of climate change risks for each type of estuary found in NSW.

Module-4 addresses the following questions:

• What is the ecological significance of estuarine habitats in NSW?
• Which ecological estuarine communities are found in NSW estuaries?
• How might estuarine organisms respond to environmental stressors due to climate change?
• How does the type of estuary influence the level of exposure to climate change stressors and which communities are most sensitive?
• What is the likely climate change impact on NSW estuarine species?

Download Module 4: "Ecological responses to climate change, opens in a new window"

Managing local stressors to enhance the resilience of estuarine ecosystems to climate stressors

Worldwide estuaries are a location subject to increasing population pressures. However they will also be subject to increasing climate change pressures. Module-5 details how these two forces interact and how the local stressors on an estuarine ecosystem can influence the way it responds to climate change. Understanding how developmental and climate change stressors interact will help identify local management actions and minimise ecosystem impacts.

Module-5 addresses the following questions:

• What are the local stressors operating within our estuaries that act synergistically with climate stressors?
• When and where are negative interactions between local and climate stressors greatest along the coast?
• How might local stressors be managed to enhance the resilience of estuarine ecosystems to climate stressors?

Download Module 5: "Managing local stressors to enhance ecological resilience, opens in a new window"

A review of sea level rise in estuaries

In practice, each estuary requires a site-specific risk assessment that takes into account the locally variable changes in climate, the unique hydrological and geomorphological setting, and the ecosystem that it supports.

This Module is a detailed review paper on how sea level rise will influence estuarine dynamics. Published in the prestigious journal, Science of the Total Environment, this paper illustrates the range of potential changes within estuaries due to rising sea levels. Unlike other modules, this section is written in the form of a peer-reviewed research paper.

Additional papers on estuary dynamics under climate change are also available and listed below:

• Influence of climate change on tidal energy:  https://doi.org/10.1016/j.rser.2021.111855, opens in a new window

• A review of the historical research in assessing sea level rise: https://www.nature.com/articles/s43247-023-00920-4, opens in a new window
• The effects of sea level rise on estuarine drainage: https://doi.org/10.1029/2021WR031405, opens in a new window
• A global assessment of estuarine tidal response to sea level rise https://doi.org/10.1016/j.scitotenv.2023.165011, opens in a new window
• Implications of estuarine entrance dynamics and climate change:  https://doi.org/10.1016/j.ecss.2020.106941, opens in a new window
• A historical review of climate change science: https://doi.org/10.1002/wcc.884, opens in a new window

Download Module 6: "Sea level rise impacts on estuarine dynamics: A review, opens in a new window"

Thresholds and ecological responses of estuarine species: Calculating eco-thresholds for baseline climate change risk assessments

Understanding how organisms respond to environmental stressors is paramount in evaluating the ecological impacts of climate change on estuarine communities. The sensitivity and resilience of species to stressors depends on their physiological tolerance and their behavioural responses.

This module presents a comprehensive review of published data on physiological thresholds of key estuarine species to climate change driven stressors. A total of 50 NSW estuarine species and more than 300 publications are reviewed and collated into a unique database of physiological tolerance thresholds.

Module-5 also provides the conceptual basis for generating the table of estuarine ecological community sensitivities presented in Module-4.

Download Module 7: "Physiological thresholds and ecological responses of New South Wales estuarine species: A review, opens in a new window"