Past the warning stage on climate

As a climate scientist who contributed to the chapter on global water cycle changes for the Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report, I am the first person to admit that the relationship between climate change, rainfall and flooding is complex. Understanding the influence climate change is having on the dynamics that cause weather extremes is the cutting edge of our field. We have already observed that historical patterns no longer seem to hold true, but because these events are playing out in real time, it’s still too early to say definitively how global warming has influenced a particular weather extreme.

Australia’s natural rainfall patterns are highly variable, so the influence of climate change on a single weather event is difficult to determine; the signal is buried in a background of a lot of climatic noise. Unlike temperature, where the human fingerprint of global warming has been clear since the 1950s, climate change’s influence on rainfall variability in eastern Australia may only begin to statistically emerge from this background of natural variability in coming decades (a clear anthropogenic signal in precipitation has already emerged across up to 40 per cent of the globe).

So, although it will take time before rainfall extremes in highly variable eastern Australia can be statistically linked to climate change, the IPCC clearly warns of the intensification of heavy rainfall events in a warming climate. Thermodynamics tells us that as our planet warms, the water-holding capacity of the lower atmosphere increases by around 7 per cent for every 1 degree Celsius of warming. This can cause heavier rainfall, and warmer ocean-surface temperatures also drive up both evaporation rates and the transport of moisture into weather systems, making wet seasons and wet events even wetter than they would otherwise be.

Changes in large-scale atmospheric circulation patterns are not as well understood as the fundamental changes in thermodynamics. Because regional rainfall is influenced by both factors, understanding the behaviour of natural weather systems that initiate the release of excess moisture from a wetter atmosphere is where much of the research effort now lies. But the truth is that this complex science will take time – we are likely to be waiting at least another decade before atmospheric science textbooks have been rewritten to describe our changing world. We are on track to breach 1.5 degrees of global warming by the early 2030s, when the IPCC’s next assessment is due. By then it will be too late to avoid some of the worst impacts of climate change.

In the meantime, how much more scientific proof do we need to consider climate change an urgent threat to the stability of human society?

A study led by social scientist Professor Elisabeth Lloyd from Indiana University in 2021 concluded that, compared with the level of evidence required by legal, regulatory or public-policy processes to establish proof “beyond a reasonable doubt”, climate science demands too much of itself, setting the evidence bar way too high, given the imminent level of threat. For example, the legal profession requires demonstration of a much lower level of proof: in the United States, the standard for a civil case in medical malpractice or patent infringement is “more likely than not”, generally interpreted as a probability of more than 50 per cent. In contrast, the IPCC requires a probability of 90–100 per cent before assigning a scientific claim, such as the attribution of a specific weather event to human-caused climate change, as “very likely”.

It’s also worth remembering that there is a long history of vested interests in the fossil-fuel industry seeking to undermine public confidence in climate science. This has resulted in a ruinous delay in our global response, landing us in the emergency we find ourselves in today.

In late February and into early March, as catastrophic flooding engulfed much of eastern Australia, the silence from the climate science community on the emergency’s relationship to global warming was deafening. In part this reflects my colleagues’ reticence to comment on matters where we still do not have enough precision in the science. Scientists tend to be very conservative by nature, and are either unwilling or unable to comment on matters with political sensitivity. That’s why the IPCC goes to great lengths to avoid being “policy prescriptive”; as scientists, we are told we must stick to the science. The problem is that other people, who are far less qualified to interpret unfolding events, rush to fill the void.

But while scientists don’t have all the answers, it must not stop us from sharing our informed, expert assessment, season after season, year after year, until the Earth’s climate is stabilised.

I am writing this completely burnt out on a Sunday after working through four summers in a row to fulfil my IPCC commitments and finish a book about the experience to help warn the public. I am doing this because I happen to live in the flood-affected region of northern New South Wales and have family in Lismore who have either lost their home, business and/or all of their possessions to this disaster. It’s my husband’s home town. This event cut me to the bone.

As a climate scientist, I want to be clear: this is what climate change looks like. Climate change isn’t just about numbers on a graph, it’s about the people and places we love. It’s about the stability of life as we know it. If this is how underprepared a wealthy country like Australia is, then imagine the situation that is going to unfold across the developing world.

It was completely surreal to witness one of the most destructive floods in our nation’s history unfold as the IPCC’s Sixth Assessment Report on “Impacts, Adaptation and Vulnerability” was released. The report stated that the choices we make this decade will determine humanity’s future. The key message, which United Nations Secretary-General António Guterres described as “an atlas of human suffering and a damning indictment of failed climate leadership”, uses the most direct and urgent language I’ve ever seen in an IPCC report:

The cumulative scientific evidence is unequivocal: Climate change is a threat to human wellbeing and planetary health. Any further delay in concerted anticipatory global action on adaptation and mitigation will miss a brief and rapidly closing window of opportunity to secure a liveable and sustainable future for all.

As Brisbane began breaking its iconic 1974 rainfall records, it became clear that this threat was upon us: things were going to get messy. The city was pounded by 677 millimetres of rainfall in just three days – more than Melbourne normally receives in an entire year. Following the 2017–20 drought, Wivenhoe Dam, Brisbane’s main water supply, was only at 58 per cent capacity before the rain event hit, which meant it could buffer the city from phenomenal volumes of water. In just three days, water levels in the dam trebled to 180 per cent capacity as the weather system stalled and started funnelling more and more tropical moisture from surrounding oceans running about 1 degree warmer than average. Had this event happened on the background of wetter conditions such as the 2011 Brisbane floods, when Wivenhoe was already at around 100 per cent capacity, the flooding would have been absolutely catastrophic.

But just over the border in northern NSW, people were not as lucky. Following a wet spring and summer caused by La Niña conditions in the Pacific, the catchments were saturated and primed for flooding. At Dunoon, north of Lismore, 775 millimetres of rain fell in 24 hours. It was the second highest daily rainfall total on record in NSW.

Before February 2022, the highest recorded Lismore flood levels were in 1954 and 1974, when flood heights reached 12.27 metres and 12.15 metres respectively. When you walk around Lismore, the 1974 flood heights tower above you on power poles in the central business district, a reminder of a dramatic past. But the 2022 flood was not caused by cyclonic conditions or preceded by prolonged wet conditions that characterised much of the 1950s and 1970s. Instead, northern NSW was coming off the back of the severe 2017–20 drought. After Australia’s hottest and driest year on record – the landscape was so bone dry that even rainforests burned – I thought it would take years before it would become saturated enough to seriously flood again.

When the Bureau of Meteorology issued its flood warning for Wilsons River, which flows through Lismore, on Sunday, February 27, it predicted rises of 11.50 metres, similar to the heights reached in the 2017 floods caused by Ex-Tropical Cyclone Debbie. Locals in flood-prone areas responded, moving as much as possible to higher ground. People worked for hours, filling the upper stories, attics and mezzanines of houses and businesses to above the 1974 flood height, which has long been used as a measure to prepare for floods. That night, my husband called his sister, whose home was above historical flood levels, to move her car to higher ground. Just in case. I’d been watching the torrential rain battering Brisbane, so I had an uneasy feeling about the extreme conditions starting to drift further south. The last thing I texted my sister-in-law before going to bed that night was: “Brisbane has now broken its 1974 rainfall record, expect the unexpected.” By 3am next morning, Wilsons River had broken its banks and although my sister-in-law’s home was on stilts on the very edge of the 1974 flood zone, water had started filling her backyard and was rising fast up the back stairs.

The family rushed to stash their most valuable possessions higher – on makeshift platforms made by taking doors off their hinges and placing them on top of high standing furniture – but it was soon clear they couldn’t save much with the time they had left. As an artist, my sister-in-law’s priority was to save key works from her latest collection – ironically, a series of climate change–themed works celebrating Australia’s unique wildlife.

Within an hour, the water had come up so high that they had to leave immediately or risk getting trapped inside. She wrapped her terrified cat in a blanket and put it in a plastic laundry tub, along with a mobile phone, a charger and a toothbrush, and swam off the front verandah of her home into muddy floodwater in the predawn darkness. Her feet couldn’t touch the bottom until she swam around 100 metres up her street.

While it’s easy to cast judgement on people who live in flood-prone towns such as Lismore, it is unfair to claim they were unprepared. It was impossible to prepare for a flood that would go on to obliterate historical flood levels by a full 2 metres. I tracked the Wilsons River flood level online, watching on in horror as it reached a staggering 14.40 metres. Climate records are not usually broken by such monstrous margins. I couldn’t comprehend the implications of what I was witnessing; the nausea was sickening.

The people of Lismore are one of the most resilient, flood-prepared communities in Australia. We saw extraordinary scenes of locals rescuing each other from rooftops in their boats, tinnies, jetskis and kayaks. They didn’t wait for the handful of SES boats to be deployed. Our family relayed stories of people in more remote areas setting off in their boats with cordless angle grinders to cut people out of their homes’ roof cavities, where they’d been forced to retreat. Trying to sleep with the sound of landslides crashing through the valleys. The fuel and food shortages. The mud. The terrible stench of death and debris. A town utterly destroyed.

As I write two weeks on, I still have family trapped by landslides without electricity, as powerlines have tumbled down saturated hillslopes that collapsed under the weight of torrential rain. My father-in-law’s business of close to 30 years in south Lismore has been completely destroyed, roller doors bowed by the weight of floodwaters and the contents of a motorcycle mechanic’s workshop churned like the spin cycle of a colossal washing machine. When asked if the army had been past to help, he replied, “What army?”

It’s easy to understand why people feel so abandoned by this government. My father-in-law is still in shock. The roads are a complete mess, so he hasn’t been able to return to his home in the rainforest, where a landslide has pushed part of the building off its stumps. He jokes that it might be time to finally retire, but the truth is he has no choice – like many businesses in Lismore, he is uninsured and unlikely to get his business running again after this and the twin blows of the 2017 floods and the pandemic. He is one of many people in the region who have been broken by this event. An extra $1000 in people’s bank accounts (or $3000, it seems, if you’re in a Coalition seat) isn’t going to do much. A credible climate policy is the only thing that is going to safeguard the future of our communities.

Yet Australia still plans to expand the fossil-fuel industry – 72 new coal projects and 44 new gas projects are under development, heavily supported by government subsidies. These projects would more than double Australia’s gas and coal production, resulting in 1.7 billion tonnes of greenhouse gases each year, equivalent to twice the emissions of global aviation.

According to the International Monetary Fund, in 2020 global governments spent US$450 billion in direct subsidies to the fossil-fuel industry – four and a half times more than developed countries are willing to spend financing climate-change adaptation in vulnerable regions.

While I desperately hoped that the COP26 climate-change conference would be the political tipping point that changed everything, corporate interests are still willing to sacrifice our planetary life support system to keep the fossil-fuel industry alive for another handful of decades.

As long as the protection of this industry continues, real reductions in greenhouse-gas emissions will not be possible in time to avoid adding to the “atlas of human suffering”. Many of our political leaders still don’t have the heart or the courage to be moved by the tragedies we see unfolding around us. The truth is that we will not see the political response we need to address climate change until we have the collective cultural awakening that redefines the social norms that are destroying life on Earth. Individual voters are also responsible for creating or removing the social licence that maintains the fossil-fuelled status quo.

As a climate scientist, I find myself in the extraordinary position of trying to write about an emergency that is unfolding in real time. I don’t know how this story will end. But what I do know is that Australians no longer have the luxury of being apolitical.

Under current policies, global temperatures are on track to increase by 2.0 to 3.6 degrees, with a central estimate of 2.6 degrees by the end of the century. Given the lived experience of extreme events that we have seen with just 1.1 degrees of global warming, it is impossible to fathom the extreme suffering and destruction that we will witness within our lifetimes. We must reconnect with our shared humanity and do everything in our power to stabilise the Earth’s climate. This madness must stop. The era of fossil fuels must come to an end.

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