Potential Climate Change Impacts Potential Potential Climate Change Impacts on Geodiversity in the Tasmanian Wilderness World Heritage Area: on Geodiversity Geodiversity A Management Response Position Paper in the Tasmanian Wilderness World Heritage Area: Area: Heritage World Wilderness Tasmanian A Management Response Position Paper Position A Management Response A Consultant Report to the Department of Primary Industries, Parks, Water and Environment, Tasmania By: Chris Sharples Consultant November 2011 Nature Conservation Report Series 11/04 10630BL NIO M O UN IM D R T IA A L • P • W L O A I R D L D N H O E M R I E Resource Management and Conservation T IN A G O E • IM 134 Macquarie Street Hobart PATR United Nations World GPO Box 44 Hobart TAS 7001 Department of Educational, Scientific and Heritage Cultural Organization www.dpipwe.tas.gov.au Primary Industries, Parks, Water and Environment Citation: Sharples, C. (2011) Potential climate change impacts on geodiversity in the Tasmanian Wilderness World Heritage Area: A management response position paper. Resource Management and Conservation Division, Department of Primary Industries Parks Water and Environment, Hobart, Nature Conservation Report Series 11/04. This report was prepared under the direction of the Department of Primary Industries, Parks, Water and Environment (World Heritage Area geodiversity program). Commonwealth Government funds were provided for this project through the World Heritage Area program. The views and opinions expressed in this report are those of the author and do not necessarily reflect those of the Department of Primary Industries, Parks, Water and Environment or those of the Department of Sustainability Environment Water Population and Communities. ISSN: 1441-0680 (book) ISSN: 1838-7403 (web) Copyright 2011 Crown in right of State of Tasmania Apart from fair dealing for the purposes of private study, research, criticism or review, as permitted under the Copyright Act, no part may be reproduced by any means without permission from the Department of Primary Industries, Parks, Water and Environment. Published by the Land Conservation Branch, Department of Primary Industries, Parks, Water and Environment, GPO Box 44 Hobart, 7001 Cover Photo: The Gell River headwaters around Innes High Rocky (centre of photo), west of the Denison Range in the Tasmanian Wilderness World Heritage Area (TWWHA), are dominated by slopes and ridges of siliceous Precambrian quartzite bedrock blanketed by organic moorland soils. Increasing temperatures, drier summers and a higher risk of intense bushfires – all of which are projected impacts of climate change for this region by 2100 – could result in significant degradation and loss of these soils – at least on slopes – with potential impacts for aesthetics, fluvial processes, vegetation communities and habitats, and carbon sequestration. Although the degree of organic soil loss likely to occur depends on a range of poorly- understood processes and thresholds, in the worst case scenario climate change impacts on these soils would result in major changes to the character and natural processes of large portions of the TWWHA, and the release of large quantities of previously-sequestered carbon. Photo by Chris Sharples. Potential Climate Change Impacts on Geodiversity in the Tasmanian Wilderness World Heritage Area: A Management Response Position Paper A Consultant Report to the Department of Primary Industries, Parks, Water and Environment, Tasmania By: Chris Sharples Consultant November 2011 Nature Conservation Report Series 11/04 Contents Page no. EXECUTIVE SUMMARY 1 TECHNICAL SUMMARY 3 1.0 INTRODUCTION 11 1.1 Purpose, Scope and Structure of this Position Paper 11 1.2 Glossary of Selected Terms and Acronyms 13 1.3 Acknowledgements 13 2.0 PROJECTED CLIMATE CHANGES FOR THE TASMANIAN WILDERNESS WORLD HERITAGE AREA (TWWHA) 14 2.1 Introduction 14 2.2 Projected Changes to Primary Climate Variables for Tasmania and the Tasmanian Wilderness World Heritage Area 15 2.2.1 Overview 15 2.2.2 Temperature and related variables 15 2.2.3 Rainfall and related variables 19 2.2.4 Winds 23 2.3 Projected Changes to Consequential Landscape Process Effects in the Tasmanian Wilderness World Heritage Area 24 2.3.1 Introduction 24 2.3.2 Fire Regimes 25 2.3.3 Vegetation 25 2.3.4 Sea-level Rise 26 2.4 Consequences of Climate Projection Uncertainties 27 3.0 KEY GEODIVERSITY THEMES AND GEOMORPHIC SYSTEM CONTROLS OF THE TWWHA 29 3.1 Introduction 29 3.2 Active Process Themes 29 3.2.1 Introduction – Theme Characteristics and Values 29 3.2.2 Fluvial Geomorphic Process Systems and Features 31 3.2.3 Slope Mass Movement Geomorphic Process Systems and Features 35 3.2.4 Soil Process Systems and Features 39 3.2.5 Coastal Geomorphic Process Systems and Features 43 3.2.6 Karst Geomorphic Process Systems and Features 47 3.2.7 Alpine Geomorphic Process Systems and Features 54 3.3 Relict Geoheritage Themes 58 3.3.1 Introduction – Theme Characteristics and Values 58 3.3.2 ‘Soft’ Relict Landforms 58 3.3.3 ‘Soft’ Relict Sediment and Bedrock Contents 59 3.3.4 ‘Hard’ Relict Bedrock Landforms 61 3.3.5 ‘Hard’ Relict Bedrock Contents 62 4.0 POTENTIAL EFFECTS OF PROJECTED CLIMATE CHANGES ON THE GEODIVERSITY AND GEOMORPHIC SYSTEM CONTROLS OF THE TWWHA 65 4.1 Introduction 65 4.2 Potential Climate Change Impacts on Active Geomorphic and Soil Process Themes 65 4.2.1 Introduction 65 4.2.2 Fluvial Geomorphic Process Systems and Features 66 4.2.3 Slope Mass Movement Geomorphic Process Systems and Features 71 4.2.4 Soil Process Systems and Features 73 4.2.5 Coastal Geomorphic Process Systems and Features 77 4.2.6 Karst Geomorphic Process Systems and Features 82 4.2.7 Alpine Geomorphic Process Systems and Features 85 ii 4.3 Potential Climate Change Impacts on Relict Geoheritage Themes 88 4.3.1 Introduction 88 4.3.2 ‘Soft’ Relict Landforms 88 4.3.3 ‘Soft’ Relict Sediment and Bedrock Contents 89 4.3.4 ‘Hard’ Relict Bedrock Landforms 91 4.3.5 ‘Hard’ Relict Bedrock Contents 92 5.0 RANKING OF POTENTIAL CLIMATE CHANGE IMPACT RISKS FOR GEODIVERSITY IN THE TWWHA 94 5.1 Introduction 94 5.2 Criteria for Ranking Impact Risks 94 5.2.1 Introduction 94 5.2.2 Likelihood Scale Criteria 95 5.2.3 Consequence Scale Criteria 95 5.3 Risk Priority Rank Matrix for Climate Change Impacts on TWWHA Geodiversity 98 6.0 MANAGEMENT RESPONSES TO POTENTIAL CLIMATE CHANGE RISKS AND IMPACTS ON GEODIVERSITY IN THE TWWHA 100 6.1 Introduction – A Basis for Identifying Possible and Appropriate Management Responses 100 6.2 Possible Management Response Options 101 6.2.1 Do Nothing 102 6.2.2 Recording, Sampling and Preserving Information Likely to Otherwise be Irreversibly Lost 102 6.2.3 Monitoring and Researching Processes of Climate Change Response 102 6.2.4 Selective Limited Intervention to Mitigate Process Change in the TWWHA 103 7.0 PRIORITISATION OF MANAGEMENT RESPONSES TO CLIMATE CHANGE RISKS AND IMPACTS ON GEODIVERSITY IN THE TWWHA 105 7.1 Management Response Priorities 105 8.0 CONCLUDING RECOMMENDATIONS 113 Concluding Caveat 116 BIBLIOGRAPHY 117 iii Summary Executive Summary The purpose of this position paper is to identify (insofar as is possible on current knowledge): the potential effects of projected climate changes on the geodiversity of the Tasmanian Wilderness World Heritage Area (TWWHA); possible management responses to these risks; and to: propose a framework for prioritising consideration of such management responses as may be possible and beneficial. Recent (2010) modelling of projected changes to Tasmanian climates to 2100 has been prepared by the Climate Futures project of the Antarctic Climate and Ecosystems Co-Operative Research Centre. These projections have been used to systematically identify potential changes to and impacts upon geological, geomorphological and soil features and processes (geodiversity) in the TWWHA, by identifying the role that climate variables play in governing these processes and hence identifying how changes in climate may affect them. Whilst this is a powerful method of analysis which has identified a range of plausible potential impacts, it is acknowledged that currently - unpredictable feedback processes in natural systems may result in additional or in some cases differing impacts which cannot yet be identified. The view adopted in this position paper is that some degree of pervasive impacts or changes to geodiversity in the TWWHA is likely to occur, albeit of widely varying magnitudes. It is in general unlikely to be beneficial (in terms of the TWWHA management objectives) to attempt to prevent or significantly mitigate those impacts because of the large (global) scale of the driving processes, the likely huge expense of the „geo-engineering‟ that would be required, and in particular the probability that such interventions would compromise other natural TWWHA processes and values. In effect, the natural systems of the TWWHA will evolve in response to climate change, and since a significant degree of global climate change is now „locked in‟ there seems little point or justification in attempting to prevent this. Given this, it is evident that the goal of management in the TWWHA should be to manage the consequences of change rather than to attempt to stop it happening. From this perspective, four fundamental management response options to potential impacts on TWWHA geodiversity have been identified, namely: 1. Do Nothing. In many cases this will be the only realistic option, however in some circumstances other limited active responses may be justified, namely: 2. Recording and sampling. To record information about and/or contained within landforms or deposits expected to be largely destroyed by accelerated erosion processes resulting from climate change; or: 3. Monitoring and research. Where a better understanding of climate change processes and impacts on geodiversity occurring in the TWWHA may enable better planning of responses to climate change within and/or beyond the TWWHA; or: 4.