In October 2013, as fires raged through the Blue Mountains, former Prime Minister Tony Abbott stood in front of the media and stated that climate change played no role in the extreme conditions Australia was experiencing at that time or, he implied, at any other time:
“…at some point in the future every record will be broken but that doesn’t prove anything about climate change. It just proves that the longer the period of time, the more possibility of extreme events,” Mr Abbott said.
Intuitively it seemed like a fair statement. But the scientific data tells us a very different story.
How we develop misplaced perceptions of climate extremes
Members of the community often come to their understanding of the cause of extreme events through the partial information they receive from public figures such as Mr Abbott, the media, and through subjective life experiences.
Unlike climate scientists, most people do not live day-to-day with the scientific data. Instead, these subjective understandings may be based on distant hot childhood summers or an over zealous response to an experience of recent extremes.
Although many of us have visceral memories or strong beliefs about our experience of the climate, it is impossible for an individual to perceive changes in the climate system and to distinguish long-term changes from the day-to-day natural variability we already experience as ‘the weather’.
This is where scientific evidence is crucial – to help us acquire knowledge beyond our own personal perceptions.
In a new study, I discredit some common misplaced perceptions of climate extremes by investigating three of Abbott’s claims using a scientific approach. Abbott’s statements about climate change are an important starting point for the study, as they are influential, widely held, and repeated by other politicians, media commentators and members of the public.
Claim 1: We can expect increasing record-breaking hot temperatures because we now have longer records of climate.
Tony Abbott’s statement during the 2013 fires has now been used frequently as an argument against the link between climate change and extreme heat events. He said that over time we would see more records broken due to natural climate variations.
Scientific response: My study has found that the opposite is in fact true.
Statistically, if climate system is stable and unchanging, then we should expect fewer records broken through time, not more. Instead we have seen a dramatic increase in hot records in Australia in the last 15 years.
Claim 2: We can expect more record breaking-temperatures because of natural climate influences.
This claim refutes the link between climate change and extremes by falling back on the influence of natural climate change. In this argument, the increase in hot records in recent years is linked to natural changes, rather than anthropogenic warming.
Mr Abbott has also made statements about the world having cooled. In 2009, the year he claimed climate change was “absolute crap” he said, “…there doesn’t appear to have been any appreciable warming since the late 1990s”. Earlier, he said “there may have even been a slight decrease in global temperatures (the measurement data differs on that point) over the past decade”.
Scientific response: Abbott’s logic is deeply flawed here too. Not only are Abbott’s claims readily refuted by scientific data, they are contradictory.
If climate change really is “absolute crap” and the world has cooled, then we the probability of extreme heat events would be lower, not dramatically increased in the last 15 years.
Further, scientific data refutes Abbott’s dismissal of both climate change and recent warming. Data shows that Australian temperatures have increased by nearly 1°C since 1910 and this long-term warming trend is linked to greenhouse gases. As a result, the probability of record-breaking temperatures has increased dramatically in the last 15 years. In short, there is no evidence that a natural cause is responsible for the rise in extreme heat events in Australia.
Claim 3: We cannot link extreme climate events to climate change.
Abbott has outright dismissed of the link between extremes and climate change as “complete hogwash”.
Scientific response: In recent years climate scientists have been able to provide quantitative statements about how climate change has changed the risk of an extreme event and whether or not it can be attributed to climate change.
Observational climate data shows that in Australia and globally hot records are occurring far more frequently than cold records. Indeed hot records are being broken globally at a rate of 3:1 compared to cold records.
Using climate models as another line of scientific evidence, we see that the probability of increased record-breaking temperatures in Australia in recent years only occurs in climate models that include greenhouse gases, and not models that only factor in natural climate variations.
As a result, we can now say that the record hot spring temperatures that occurred in 2013 at the time of the Blue Mountain bushfires were 50 times more likely because of human-caused climate change.
A scientific explanation for increasing record-breaking heat
There is only one source of information where we can find a consistent and comprehensive explanation for the long-term warming trend and the rise in recent extreme temperatures in Australia. Scientific data tells us human caused global warming, driven by our greenhouse gas emissions are a major factor in recent extremes heat.
If you are not working close to objective data like climate scientists, it is understandable that you can be misled by seemingly sensible and intuitive public pronouncements that try to sever the link between global warming and extreme heat events.
However, these pronouncements should join Abbott on the backbench. Scientific data shows that Australia’s dramatic increase in recent record-breaking hot temperatures is clearly linked to anthropogenic global warming.