Understanding and managing impacts of climate change and variability on vegetable industry productivity and profits Dr Gordon Rogers Applied Horticultural Research Pty Ltd Project Number: VG12041 VG12041 This report is published by Horticulture Australia Ltd to pass on information concerning horticultural research and development undertaken for the vegetables industry. The research contained in this report was funded by Horticulture Australia Ltd with the financial support of the vegetables industry. All expressions of opinion are not to be regarded as expressing the opinion of Horticulture Australia Ltd or any authority of the Australian Government. The Company and the Australian Government accept no responsibility for any of the opinions or the accuracy of the information contained in this report and readers should rely upon their own enquiries in making decisions concerning their own interests. ISBN 0 7341 3197 6 Published and distributed by: Horticulture Australia Ltd Level 7 179 Elizabeth Street Sydney NSW 2000 Telephone: (02) 8295 2300 Fax: (02) 8295 2399 © Copyright 2013 HAL Project Number: VG12041 (Review completed April 2013) Understanding and managing impacts of climate change and variability on vegetable industry productivity and profits Gordon Rogers, Kelvin Montagu Applied Horticultural Research 1 Horticulture Australia Project Number: VG12041 April 2013 Project Leader: Gordon Rogers Applied Horticultural Research Suite 352, Biomedical Bldg 1 Central Ave Eveleigh NSW 2015, Australia Key Personnel: Gordon Rogers – AHR Snow Barlow – University of Melbourne Kelvin Montagu – Colo consulting Jann Conroy – University of Western Sydney Michael Brear – Parkside Energy Michael Blyth – Four Scenes Funding This project has been funded by HAL using levy funds from the Australian vegetable industry and matched funds from the Australian Government. The broad objective of this project was to assess the likely impacts of climate change and variability on the productivity and profitability of Australian vegetable industry in the near and medium term, to identify measures that could be undertaken to minimise any adverse impacts and take advantage of opportunities. Any recommendations contained in this publication do not necessarily represent current HAL Limited policy. No person should act on the basis of the contents of this publication, whether as to matters of fact or opinion or other content, without first obtaining specific, independent professional advice in respect of the matters set out in this publication. 2 Contents 1 Executive Summary .................................................................................................................................. 9 2 Introduction ............................................................................................................................................... 13 2.1 Climate change and variability – what has already occurred? .................................... 14 2.1.1 Risk analysis of climate change from a broad perspective ................................... 15 2.1.2 What we know about the atmosphere and climate ................................................. 17 2.1.3 What could happen to the climate? ................................................................................. 18 2.1.4 Will there be more extreme weather events? ............................................................ 18 2.1.5 Will variability in the weather increase, and if so in what way? ........................ 21 2.2 What would 4 degrees of global warming look like? ....................................................... 23 2.3 Climate variability ........................................................................................................................... 24 2.4 What are the predicted impacts at the industry level? ................................................... 25 2.5 Regional risk assessments: Overview .................................................................................... 25 2.5.1 Understanding the likelihood of changes to key climate variables in a region 26 2.5.2 How good have past climate change projections been? ........................................ 28 2.5.3 Exploring the consequence of the projected changes in climate on the vegetable growing region – “Discussion Starters”. ................................................................. 30 2.6 Regional risk assessments: Interpretation .......................................................................... 31 2.6.1 General guidance on interpreting the climate change projections ................... 31 2.6.2 What does a MEAN mean? .................................................................................................. 32 2.6.3 Manjimup case study, December 2012: Climate is what you expect – weather is what you get. ..................................................................................................................... 32 2.6.4 Frost .............................................................................................................................................. 34 2.6.5 Crop water use ......................................................................................................................... 35 2.7 Temperature and rainfall projections to 2035 for vegetable growing regions in Australia ......................................................................................................................................................... 37 2.7.1 Summary of predicted changes ........................................................................................ 37 2.7.2 Manjimup ................................................................................................................................... 38 2.7.3 Gatton ........................................................................................................................................... 41 2.7.4 Hay ................................................................................................................................................ 44 2.7.5 Werribee ..................................................................................................................................... 47 3 2.7.6 Murray Bridge .......................................................................................................................... 50 2.7.7 Devonport .................................................................................................................................. 53 2.8 Graphical representations of expected regional changes in temperature in response to an increase of 1oC in average temperatures. ......................................................... 55 2.8.1 Summer: Predicted average monthly maximum temperature changes per oC of average warming .............................................................................................................................. 55 2.8.2 Autumn: Predicted average monthly maximum temperature changes per oC of average warming .............................................................................................................................. 57 2.8.3 Winter: Predicted average monthly maximum temperature changes per oC of average warming .............................................................................................................................. 58 2.8.4 Spring: Predicted average monthly maximum temperature changes per oC of average warming ................................................................................................................................... 60 2.9 Predictions of the impact of increased climate variability and change on eight vegetable crops ............................................................................................................................................ 61 2.9.1 Carrots ......................................................................................................................................... 62 2.9.2 Lettuce (Cos, Iceberg, fancy) .............................................................................................. 63 2.9.3 Capsicums .................................................................................................................................. 64 2.9.4 Broccoli ....................................................................................................................................... 65 2.9.5 Sweet corn (processing) ...................................................................................................... 66 2.9.6 Beans ............................................................................................................................................ 67 2.9.7 Cauliflower ................................................................................................................................ 68 2.9.8 Beetroot (processing) ........................................................................................................... 69 2.10 Regional impacts on vegetable crops in response to daily average temperature increases up to 4oC ..................................................................................................................................... 70 3 What are the impacts of increased climate variability on vegetable crops? .................. 76 3.1 Direct effects ...................................................................................................................................... 76 3.1.1 Crop growth and