How bad can climate damage get? Worse than you imagine, if Australians’ recent experience of more extreme weather and natural disasters — driven by a hotter climate — are an indication, because the past is no longer a reliable guide to the future.
Civil engineer Alan Hoban says flood maps around Australia drastically underestimate the impact climate change will have on rainfall due to conservative assumptions about how fast rainfall intensity will increase. “Very few flood maps in south-east Queensland, or even Australia, yet account for these changes,” he says.
Extreme floods and rain events are often oddly described as a “one-in-a-hundred-year” or a “one-in-five hundred-year” event, suggesting they are unlikely to recur. But then they happen again, within a few years. This shows the assessments of future climate risks are too conservative, and so vulnerable communities and governments are under-prepared.
Victoria’s Black Saturday bushfires were of an intensity not projected to occur till towards the end of the century. Parts of inland Australia are experiencing heat extremes several decades ahead of expectations. On 18 December 2019, Australia hottest day on record with an average maximum of 41.9°C, the heat in some areas aligned with worst-case 2040-2060 projections.. It’s a problem created in part by over-reliance on the reports of the Intergovernmental Panel on Climate Change (IPCC), which have a track record of being too conservative.
The Australian Government is late in delivering its first domestically-focused National Climate Risk Assessment, which was due in December, and should be the basis for emergency management, resilience and climate adaptation planning.
Will it be up to date, and will it give attention to the plausible worst-case possibilities, because they result in the greatest damage to people and property? There is reason to worry that the physical reality of accelerating climate disruption will mug Australia's risk assessment and leave us poorly prepared.
One foundation for understanding future climate impacts is how quickly temperatures will rise. And that is now a big issue, because the government’s assumption was that warming would be in the range of 1.5 to 2 degrees Celsius (°C) by 2050. And it is still the basis of most international climate policy formulation. Now it is way out of date.
Just seven years ago, IPCC scientists projected global average warming of 1.5°C would not occur till 2040. But that warming level has now been reached, fifteen years earlier than forecast. Both 2023 and 2024 reached 1.5°C, and the running average for the last 24 months has been close to 1.6°C. For all practical purposes, the warming trend has reached 1.5°C. A new World Meteorological Organization report says that Earth will cross this point in just two years, with a “70% chance that the 2025-2029 five-year mean will exceed 1.5°C above the 1850-1900 average”.
Acknowledging that a level of warming not expected till 2040 is here right now in 2025 means facing the bitter reality that fifteen years have just been “lost” from the emissions-reduction timetable.
What does that practically mean? At the 2015 Paris climate policymaking conference, the goal of holding warming to 1.5-2°C was agreed to, together with actions (in theory) to achieve net-zero emissions by 2050, based on the now-superseded warming projections. So the “lost” 15 years means that this net-zero-by-2050 goal now needs to be net-zero-by-2035.
Most policymakers, including the Australian Government, seem not to have recognised this. When the penny drops in Canberra that we are already at 1.5°C, will that realisation be reflected in the National Climate Risk Assessment?
Australia’s climate modelling capacity has been degraded. The biggest problems are lack of independent and expert scientific advice, and the lack of coordination across departments and agencies, and a culture of empire-building. Restoring a climate science advisory group to provide high-level, independent advice to the Australian government is a key task.
Scientists have been shocked at the pace of change. The rate of warming has accelerated from less than 0.2°C per decade to 0.3°C or more per decade. And tipping points are occurring now, including at both poles. Permafrost, boreal forests and the Amazon are becoming net carbon emitters.
This year, new research has reaffirmed that 1.5°C is too high to prevent tipping points: there is a significant risk of large Amazon forest dieback if global warming overshoots 1.5°C, yet we are there right now. And there is a new scientific warning that “1.5°C is too high for polar ice sheets”. The evidence grows that the 1.5°C target was never a safe target for humanity.
All of this leads to one conclusion: we are on the edge of a precipice and humanity now needs to throw everything at the climate threat, literally “all hands on deck”. The late Prof. Will Steffen’s call to make climate the primary target of policy and economics is now a survival imperative. The business-as-usual delusion embraced by policymakers that climate is just another issue is laid bare by the 1.5°C time-bomb.