"Climate change is like a dead possum under the floorboards – the stench is getting steadily worse, and you can’t hold your breath forever."
Auckland’s Changing Climate is a book for Aucklanders interested in the past, present, and future climate of the place they call home: from the convulsions of the glacial-interglacial cycles of the last two million years, through to expectations of future deluges, droughts, and heat waves.
Most of us accept that climate change is a significant global issue. Occasional media articles about the pace of global warming and the implications for things like sea level rise, extreme storms, droughts, and heat stress. However, most of what we see is fairly generic, lacking the local context that would make it most meaningful.
Yes, we all know that it’s getting warmer, and that storms are expected to get more severe, but what does it all mean? Does 2°C warming mean we will be hiding indoors with the curtains closed during summer, or will we be revelling in more nice barbecue weather? Will a 10% reduction in rainfall mean endless urban water crises? And does that expectation of more severe storms mean we should expect events like Auckland’s monster Anniversary Day storm of 2023 every few years, or decades, or centuries?
Auckland’s Changing Climate provides answers to such questions by bridging the gap between climate science and local knowledge. It outlines the key elements of Auckland’s climate, explores past climate (mainly reconstructed from pollen and tree rings), examines evidence of climate change and variability in the instrumental record, and summarises how climate is projected to evolve over the course of this century.
Selected impacts of future climate change are also examined and a picture is painted of what a future adapted Auckland may look like.
Preface
Chapter 1. “Location, Location, Location” – Key Elements of Auckland’s Climate
Chapter 2. Tales of the Lorax – Climate Change Prior to Human Arrival
Chapter 3. Kupe to Cook – Climate Change 1000–1853
Chapter 4. Heat Waves, Droughts, & Deluges – Scientific Observations 1853–2024
Chapter 5. Polishing the Crystal Ball – Auckland’s Climate in a Warming World
Chapter 6. Final Thoughts
Appendix – Central Auckland Meteorological Observatories
Glossary
Figure Credits
References
Index
126 pages
69 figures
21 technical boxes
Climate change has become so much a part of modern life that it is now rare for a week (sometimes a day) to go by without some reference to it in the media. Floods, droughts, fires, heat waves, rising seas, insect infestations, and other plagues are all presented as the actual and anticipated consequences of global warming. We may push it to one side when other immediate crises capture our attention, but it is always back. It’s like a dead possum under the floorboards – the stench is getting steadily worse, and you can’t hold your breath forever.
Most of us accept that climate change is a significant global issue. We understand that human activity is altering the composition of the atmosphere and that this is having major impacts on climate. Some of those impacts are well understood and large scale, such as sea-level rise implications for coastal areas everywhere. But others are more regional in scale, such as the opening of summer sea lanes through the Arctic, coral bleaching, human migration associated with large-scale desertification, and changes to the frequency and severity of local extreme weather events. Perhaps most of us also know that our past actions (especially burning fossil carbon) have locked in some level of global warming for the next sev-eral decades, but that decisions related to mitigation will significantly affect the scale of adaptation that the next few generations will face.
Climate scientists write (often impenetrable) papers about climate change in academic journals. This is how scientific knowledge progresses, but it can be a daunting task to keep up, and potentially confusing if you try. As ideas are proposed, developed, debated, and sometimes refuted, it is possible for vested interests to cherry pick the literature to support their agendas, or even suggest that the ongoing debates justify doing nothing yet. The scientists know that those messy debates are science in action and only at the fringe of a broader consensus about ongoing and significant global warming. But critical and expensive decisions about mitigation and adaptation are ultimately made by politicians. They, of course, always have other competing priorities, so action requires a clear scientific message and a public convinced that something does need to be done.
Recognising the potential importance of global warming and the need for a clear expression of the state of the science, the Intergovernmental Panel on Climate Change (IPCC) was established in 1988. Multiple voluminous reports, technical summaries, and summaries for policy makers have followed. These get reported in the media every few years, mostly at global scale. Then a few years later, further research provides the bridge to the local level through additional papers, reports, and press releases. Importantly, regional climate change scenarios provide the detail needed for other researchers to investigate potential future impacts on things like drought and flood risk, agricultural productivity, and human and animal heat stress.
I have watched the cycle of cascading global New Zealand regional local science for over thirty years. We are currently in the sixth iteration, which suggests that it has served us well. The professionals and (hopefully) the policy makers are well informed about the seriousness of the issue; especially as gradually more definitive language has been used to express the climate change consensus. But I think something is missing. Yes, we all know that it’s getting warmer, and that storms are expected to get much more severe but, apart from occasional media coverage, the critical local context is often missing. Does 2°C warming mean we will be hiding indoors with the curtains closed during summer, or will we be revelling in more nice barbeque weather? Will a 10% reduction in rainfall mean endless urban water crises? And does that expectation of more severe storms mean we should expect events like the Anniversary Day storm of 2023 every few years, or decades, or centuries? If the public has little basis for answering questions such as these, then a clear consensus regarding the significance of future local climate change may be elusive. And without that, those wanting to persuade politicians to act are likely to be thwarted.
The purpose of this book is to provide Aucklanders with some local context to global warming by bringing climate change “home”. In a sense, I think we are all part-time climatologists once we have lived in a place for a while, because we come to understand some of the nuances of our local climate. For Aucklanders, that includes knowing that a heavy coat is rarely required, that the trials of commuting may be compounded by torrential downpours (but not by snow drifts), that it usually gets uncomfortably sticky in summer, and that droughts often result in political panic. If you are one of Auckland’s part-time climatologists, then I am hoping to make climate change more “real” for you by leveraging off your local knowledge.
So, who is this book is written for? The target audience is Aucklanders interested in the past, present, and future climate of the place they call home – from the convulsions of the glacial-interglacial cycles of the last two million years, through to expectations of future deluges. I set out to write an accessible synopsis of the science, pitched at the level of a Year 13 student or first-year University undergraduate.
Inevitably though, complexity sometimes simply cannot be avoided if a coherent story is to be told. In view of this, I have tried to keep the main text moving along at a reasonable clip without getting bogged down. Footnotes and Boxes flesh out complex or incidental (but hopefully interesting) details. The boxes can be read in conjunction with the main text or followed up later, if you want to know a little more about, say: why average temperature isn’t; why there was a wee spat amongst climate scientists about a little wooden box in Albert Park; or why radio talk-back hosts don’t understand return periods. Because some of the boxes do get a bit technical, I have given them a complexity code represented by zero to three dragon symbols in the top-right of the boxes (in the spirit of Here Be Dragons). If you get flummoxed by a two or three dragon box, you can at least rest assured that my second- and third-year undergraduate students probably were too.
The basic structure of the book is from past to future. However, it starts with a look at the fundamentals of Auckland’s climate, as context for future projections. For example, it makes sense to discuss how El Niños will affect Auckland’s climate in a warmer world in the context of understanding how they have impacted us over the last several decades. Chapter One then can be seen as a bit like formalisation of your inner climatologist knowledge.
Just as understanding our present climate helps place future projections in context, so does knowledge of the past. There are two points I want to make in this context. First, climate is characterised by change and variability at all time scales, which will be influenced by human-caused global warming (e.g. how future El Niño events impact us) but will still be with us. Second, because we have some knowledge of the scale of past climate change and its impacts, especially the environmental convulsions associated with repeating glacial to inter-glacial cycles, we therefore have some basis for determining the significance of projected future changes.
Related to the last point, knowledge of past climate change and variability also informs our understanding of how Auckland’s future is likely to evolve. For example, we know that Auckland’s climate is significantly affected by sub-tropical influences, such as those atmospheric rivers that bring summer deluges. Studying the past tells us how tropical influences have waxed and waned with global warmth. Projections of future climate derived from climate modelling are most credible if they are consistent with what the past tells us.
Some of the material in this book comes from my own research, with colleagues, on Auckland’s climate over the last 40 years, especially that related to climate reconstruction from kauri tree rings, deluges, droughts, and water resources. Other material is distilled from the publications of other climate scientists, notably those at crown research institutions and the universities. I have taken a minimalist approach to referencing, but links to key sources are provided in the footnotes and in a Figure Credits section at the end of the book. Most of the references are papers written for scientific journals. I have attempted to pick the eyes out of these and present the key information in a way appropriate for a lay audience. I hope that I have not misrepresented or trivialised the important work of my colleagues!
Special thanks to those colleagues who took time out of their busy lives to check one or more chapters for howlers: Paul Augustinus, Gretel Boswijk, Andrew Lorrey, and Rewi Newnham. And to my family for keeping my English under control, stopping me getting too engrossed in the science, and for at least pretending to find my attempts at humour remotely funny.