Australia's summers are getting longer and hotter, and the data hides extreme heat. While the overall Australian summers of the past show daytime temperatures have risen by just over 1 degree Celsius since the 1950s, it's the day-to-day temperatures that impact our lives. In some instances, just 1-2C of warming across the season has amounted to four times as many individual extreme heat days. The increase in extreme heat days can be seen in most capital cities, with Adelaide and Canberra experiencing the most significant jumps. The reality of today's summers is that they are becoming longer and hotter, and the data hides extreme heat. Let's take a closer look at Perth, the capital which gets the hottest extreme temperatures during summer. In the era prior to 1975, a day over 41.3C was considered extreme. This is not a random number. Only 1 per cent of summer days hit that temperature. In the 25 summers from 1950-75, it occurred 25 times. So, once a summer on average. Without any change to the climate, that frequency should stay about the same. But that's not the reality of what Perth has seen. Instead, it nearly triples. The rarer the extreme, the more obvious that increase is in the charts. For many, this is especially clear since the turn of the millennium. In Melbourne, days over 42C have occurred as many times since the year 2000 as they did in the 90 years before that. Personally, I think this is a fascinating example of how our memories work. According to behavioural psychologists, it's to do with the way our memories work. University of New South Wales professor Ben Newell says our memories aren't perfect records of data. Instead, they're coloured by emotional experience. Specific salient events or emotionally vivid events will come to mind readily and those will start to colour people's overall perception of when it was hot. So you get this sort of biasing. Professor Newell also said we're quite good at recalibrating a new normal. The 'moderating' influence of the coast is another factor to consider. Brisbane and Sydney do not see the same strong increase in extreme heat days. This is because the observing sites for both cities sit close to the coast, explains BOM senior climatologist Blair Trewin. Regular breezes off the ocean can help to moderate the really high temperatures during the summer months. The season's changing shape is another interesting observation. Summer isn't just getting hotter. For some, it's also getting longer. This is most noticeable in Canberra, but Adelaide and Perth also show a noticeable change. The data shows only Darwin and Adelaide are recording nights this hot. But they are coming around far more often today. The signature of this summer is a great example of how extremes can hide in the data. Overall, Australia's summer was warm but not remarkable. It was the eighth warmest summer on record for Australia. But within the season, there were several remarkable events. During two major heatwaves in January, hospital admissions went up, major bushfires broke out and big sporting events were suspended before giving way to major flooding from heavy rain systems dumping months' worth of water in days. Sixty-three all-time heat records were broken over summer, according to the BOM, almost all in the space of just one week. Port Augusta is now the southernmost location in Australia to have recorded a temperature of 50C. Even further south, Renmark in South Australia also came incredibly close to the milestone, reaching a record 49.6C in late January. As summers change, so do we. Of course, as our climate has changed, so has our ability to handle it. Robert Tucker remembers growing up without the luxuries of air conditioning. But the heat drove people to get creative with makeshift cooling systems. Most people have air conditioning. Australia now has an official heatwave warning system. The effect of heat on health and critical infrastructure, like transport and electricity, is much better understood. Beyond adaptation, Australia also has policies aimed at reducing greenhouse gas emissions to net zero by 2050 to stop the cause of the warming — something that is essential, according to climate scientists. Personally, I think this is a critical issue that requires immediate attention. While we quickly get used to this new climate, we can't let it outrun the necessary further changes to adapt and prevent it from getting worse. If we believe the idea that people are slowly shifting their baseline and perception of what counts as remarkable types of weather, then the urgency with which to change is not quite so prominent. It's kind of an illustration of the boiling frog, really. Things are incrementally getting worse, but we don't move the needle on it. This is not just a consideration for the current generation, but for those to come. If you care about your grandkids, then you should care about climate change.
