HEATWAVES: HOTTER, LONGER, MORE OFTEN The Climate Council is an independent, crowd-funded organisation providing quality information on climate change to the Australian public. CLIMATECOUNCIL.ORG.AU HEATWAVES: HOTTER, LONGER, MORE OFTEN Written by Professor Will Steffen, Professor Lesley Hughes and Dr. Sarah Perkins Published by the Climate Council of Australia Limited. ISBN: 978-0-9924142-2-1 (print) 978-0-9924142-3-8 (web) © Climate Council of Australian Ltd 2014. This work is copyright the Climate Council of Australia Ltd. All material contained in this work is copyright the Climate Council of Australia Ltd except where a third party source is indicated. Climate Council of Australia Ltd copyright material is licensed under the Creative Commons Attribution 3.0 Australia License. To view a copy of this license visit http:// creativecommons.org.au You are free to copy, communicate and adapt the Climate Council of Australia Ltd copyright material so long as you attribute the Climate Council of Australia Ltd and the authors in the following manner: Heatwaves: Hotter, Longer, More Often by Professor Will Steffen, Professor Lesley Hughes and Dr. Sarah Perkins. © Climate Council of Australia Limited 2014. Permission to use third party copyright content in this publication can be sought from the relevant third party copyright owner/s. WARNING: This report may contain the images of Aboriginal and Torres Strait Islander people now deceased. This report is printed on 100% recycled paper. CLIMATECOUNCIL.ORG.AU Preface This is the second major report of the Climate Council. The Council is an independent, non-profit organisation, funded by donations from the public. Our mission is to provide authoritative, expert information to the Australian public on climate change. For the second year in a row, heatwaves global trends in heatwaves is clear and and extreme hot weather have plagued compelling. The impacts of heatwaves much of Australia. Preliminary accounts are often under-the-radar compared to of the January 2014 heatwave in Victoria other extreme weather events, but they point to significant health impacts—203 are widespread and serious, damaging heat-related deaths, a 20-fold increase in human health, infrastructure and ambulance call-outs, a four-fold increase natural ecosystems; and decreasing in calls to nurses-on-call, and a four-fold workplace performance and agricultural increase to locum doctors. Severe heat productivity. The report concludes by also afflicted areas further north: for the outlining what needs to be done to week ending 4 January 2014, average slow, and eventually stabilize, the trend maximum temperatures were 8°C or towards more severe and more frequent more above normal in southern inland heatwaves. The report draws directly on Queensland. By 9 February Canberra the peer-reviewed scientific literature had recorded 16 days above 35°C this as well as on authoritative assessments, summer, compared to the long-term such as those of the Intergovernmental average of 5.2 days. Australia’s extreme Panel on Climate Change (IPCC). A heat drew international attention reference list is provided at the end of when play in the 2014 Australian Open the report for those who would like more tennis tournament was suspended for information. the afternoon of 16 January because of the heat. Off-court ambulances We are very grateful to our team of expert treated almost 1000 tennis fans for heat reviewers and community readers, exhaustion in the first few days of the whose comments and suggestions tournament. improved the report. The expert reviewers were: Dr Lisa Alexander This report sets out the facts about (University of New South Wales), Prof heatwaves and hot weather. We explore Helen Berry (University of Canberra), the observed changes to heatwaves in Prof David Karoly (University of Australia—their severity, duration and Melbourne), Prof Tord Kjellstrom (Health timing—and place this in the context and Environment International Trust, of increasing extreme heat around Mapua, New Zealand), and Dr Sophie the world. The contribution of climate Lewis (University of Melbourne). We also change to the Australia-wide and thank the Bureau of Meteorology and CLIMATECOUNCIL.ORG.AU HEATWAVES: HOTTER, LONGER, MORE OFTEN CSIRO, which reviewed the accuracy and relevance of the science underpinning the report. Their reviews are not an endorsement of the conclusions drawn. We are also grateful for Ron Collins, Jill Dumsday and Michael Kirkpatrick’s feedback as community readers. We are also grateful to Climate Council staff for their many contributions to the production of this report. The authors retain sole responsibility for the content of the report. Professor Will Steffen Climate Councillor Professor Lesley Hughes Climate Councillor Dr Sarah Perkins CLIMATECOUNCIL.ORG.AU Contents Preface Key findings Introduction 1 1. Heatwaves are becoming longer and more intense .................................................... 2 1.1 The nature of changing heatwaves 3 In Detail 1: Variability in heatwave characteristics 10 1.2 Severe heatwaves in other parts of the world 15 1.3 The influence of climate change on heatwaves 17 2. Impacts of heatwaves .........................................................................................................20 2.1 Human health Direct impacts on health 21 Indirect impacts 27 Workplace safety and productivity 29 2.2 Infrastructure 32 2.3 Agriculture 34 2.4 Natural Ecosystems 36 3. Interaction of heatwaves with other extreme events and environmental stresses ...............................................................................38 3.1 Droughts 39 3.2 Bushfires 40 3.3 Multiple interacting stresses on coral reefs 42 In Detail 2: Multiple interacting stresses on coral reefs 43 4. Heatwaves in the future ...................................................................................................45 4.1 Projections for extreme heat globally 46 4.2 Projections of future hot weather for Australia 49 4.3 Implications of more severe heatwaves and hot weather 51 4.4 This is the critical decade 53 References 56 What to do in a heatwave CLIMATECOUNCIL.ORG.AU HEATWAVES: HOTTER, LONGER, MORE OFTEN Key findings 1. Climate change is already Russia in 2010 and several regions in increasing the intensity and the south and central US in 2011 and frequency of heatwaves in 2012. Australia. Heatwaves are becoming hotter, lasting 2. Climate change is making longer and occurring more heatwaves worse in terms often. of their impacts on people, property, communities and › Over the period 1971–2008, both the environment. Heatwaves the duration and frequency of have widespread impacts, heatwaves increased, and the ranging from direct impacts hottest days during heatwaves on our health to damage to became even hotter. ecosystems, agriculture and infrastructure. › Hot days have doubled in Australia in the last 50 years. In the last › Heatwaves pose a widespread decade, hot weather records have risk for Australians as they affect occurred three times more often people in all capital cities and than cold weather records. most regional areas. Over the past 100 years, heatwaves have caused › Several of our capital cities— more deaths than any other natural Adelaide, Melbourne and hazard. Heatwaves also restrict Canberra—are experiencing more work capacity and decrease the intense hot weather than expected. productivity of exposed workers. The increase in hot weather observed in the 2000–2009 decade › Extreme heat can damage has already reached the best infrastructure such as electricity estimate projected for 2030. distribution and transport systems, causing flow-on effects. Heatwaves › The southeast of Australia, which experienced in Melbourne in includes many of our largest recent years have disrupted the population centres, stands out as railway system and electricity grid. being at increased risk from many extreme weather events, including › Hot, dry conditions have a major heatwaves, drought and bushfires. influence on bushfires—these conditions are driving up the › The trend toward more frequent and likelihood of very high fire danger more severe heatwaves in Australia weather. Heatwaves exacerbate is part of a larger global trend. Very drought, which in turn can also severe heatwaves have occurred increase bushfire risk. elsewhere, including Europe in 2003, CLIMATECOUNCIL.ORG.AU › Heatwaves affect marine 4. Record hot days and Key findings ecosystems, particularly vulnerable heatwaves are expected to reefs. The 2011 marine heatwave increase in the future in Western Australia caused the first-ever reported bleaching of › The number of hot days, warm Ningaloo reef. Bleaching events nights and heatwaves are all on the Great Barrier Reef have expected to increase through the occurred repeatedly since the late 21st century across the globe. 1970s. › Record hot days and warm nights › Heatwaves can reduce crop yields, are also expected to increase across decrease livestock productivity Australia over the coming decades. and trigger mass deaths of heat- For both northern and southern sensitive species such as flying Australia, 1-in-20 year extreme hot foxes and birds. days are expected to occur every two to five years by the middle of › It is crucial that communities; the century. emergency services; health, medical and social services; and other › If the current trend in greenhouse authorities prepare for the increases gas emissions continues through that are already occurring in the the rest of this century, today’s severity