When you study heatwaves, you understand the urgency of a rapid reduction in the emission of greenhouse gases.
I decided to look at heatwaves around the time of the Angry Summer, back in 2012–13. Heatwaves were starting to occur globally that were unprecedented, but back then there was no real way of measuring them. We’ve come a long way since then.
Using inspiration from other studies, I proposed a framework, but I also learned that there is a good reason why we don’t define heatwaves just one way, because their impacts are hugely varied. You need an index that makes sense of their particular impacts.
I now have what you’d call a toolbox to measure heatwaves. I’ve since gone back through the climatological records and applied these different metrics, fitting them to the observations, and then I’ve been able to compute trends looking at, for example, how the rate of heatwave intensity has changed. There are different ways of analysing [heatwave] intensity – how has the rate or duration changed, their frequency, their spatial extents, that sort of thing. And we then use that same toolbox to look at projections into the future.
Depending on which emissions scenario we follow – whether it’s the really bad business-as-usual approach, or the optimum but very unlikely rapid reductions pathway, or something in between – we can then predict those future heatwaves and compare across scenarios. This way we can work out how heatwaves change over different regions relative to how much the planet warms by. Or how the heatwaves change due to natural variability, such as how the El Nino Southern Oscillation is doing.
Is there any good news? No, not really. If we limit global warming we will limit the changes in heatwaves. That’s probably about as good as it gets. The less we warm the planet, the less bad heatwave changes will be. They’re not looking good. We’re roughly on track to warm by three degrees at the moment.
I’ve looked at what happens if we reach certain global warming thresholds, even those above 3°C. It’s definitely not good news.
It’s not really possible to say categorically whether a particular heatwave was or wasn’t caused by climate change. It’s always due to the manifestation of things like natural climate variability, local weather scale processes, and climate change. Our recent ‘Black Summer‘, for example, was excessively hot. All of the records were broken – it was awful. We all know how bad it was. Climate change was definitely a factor, without a doubt. But we also had a long-term drought and we also had periods during the spring caused by natural variability, which meant that we had very low rainfall and a lot of heat build-up. So it was a combination of factors. But as we move further into the future, climate change will matter so much more than natural processes, especially in futures of 2°C global warming (or higher).
I’m not searching for that piece of science to get me a Nobel Prize, or any sort of prize. It’s not about that to me. I’m doing work that matters. This is a really important issue and we needed to solve it yesterday. For me, it’s having the science and the data to understand what exactly is going on, along with the range and severity of the impacts. We need more accurate projections and more accurate compositions of events that are driven by climate change and natural variability and synoptic-scale processes.
My interest in science was a slow progression during my adolescence. My mum always told me that I had a very analytical, logical mind, but naturally, when my mum told me to do something, I’d push right against it. So I didn’t really consider a career in science until I reached senior school, when I did geography, chemistry and biology as my electives. It was pretty clear then that science was for me.
But I soon learned that I didn’t like wearing a lab coat and meticulously squeezing chemicals from one test tube to another, so I thought doing something in atmospheric science, which is more computer-based, was a better career choice for me.
Science is about asking the questions that need to be asked. What drives me is that quest for knowledge and knowing this is such an important field. It’s not just research for research’s sake. It’s arguably the biggest challenge of our generation and generations to come.
I have aired very publicly my frustration with government. I’m very honest with how I feel. But I’m not a politician. I put the material out there and make it publicly known, and I brief government when necessary – a lot of my research went into the recent Intergovernmental Panel on Climate Change Sixth Assessment Report. The fact that we know heatwaves are changing globally, how fast they’re changing, and what the future holds for heatwaves, is backed up by work that I’ve led.
But getting people to listen (usually the politicians) is so frustrating. The first IPCC report came out when I was six years old. I was in year one, at primary school, and I’m now rapidly approaching 40. So these warnings are not new. That’s what I’m so frustrated about. I shouldn’t be continually saying, “Shit’s getting bad – why are you not listening?” It should be, “Okay, hey, look at the difference we made. Here’s a projection of how good it can be if we continue working hard!”
As told to Graem Sims for Cosmos Weekly.
Dr Sarah Perkins-Kirkpatrick is a world-renowned expert on heatwaves. She has dedicated her career to studying key features of these high-impact events, including their definition, their observed trends, future changes, underpinning physical drivers, and the role of anthropogenic influence behind observed events. She has also been at the forefront of the emerging field of marine heatwaves.