It’s ironic that the release of the latest authoritative UN climate change assessment ^[1] on Monday coincided with historic flooding in both Queensland and New South Wales. Brisbane received a record 80% of its annual rainfall within three days, while NSW Premier Dominic Perrottet described flooding in his state as a ‘one-in-1,000-year event’.

Record-setting floods also struck NSW less than a year ago. At that time, Premier Gladys Berejiklian described ^[2] it as a ‘one-in-100-year event’ that was ‘beyond anyone’s expectations’. The state dodged a bullet on that occasion; if spilling from Warragamba Dam had intensified, much of Western Sydney would have been inundated. And it dodged another bullet less than a year before that, in the same location, when the Black Summer bushfires threatened the Warragamba catchment, the source of 80% of Sydney’s water supply.

The new assessment from the Intergovernmental Panel on Climate Change confirms that it is no longer useful or accurate to describe disasters such as the recent floods and fires as one-in-100-year or one-in-1,000-year events. Those determinations are based on Australia’s historical experience of floods in a stable climate, not one in which the global average temperature has now risen by more than 1°C and is probably on its way to at least 2°C.

The rapid pace of global climate change is completely outside of human experience. In a matter of only decades, for example, what has historically been a one-in-100-year extreme coastal flood will become an annual event in many parts of the world. The NSW premier was on stronger ground yesterday when he said ^[3], ‘Past experience doesn’t mean much in an unprecedented event.’

The IPCC assessment confirms another important feature of climate change that is also now emerging in Australia and elsewhere: it’s not simply an environmental crisis, or a crisis of natural disasters, but a whole-of-society crisis. The report notes: ‘Climate change impacts and risks are becoming increasingly complex and more difficult to manage. Multiple climate hazards will occur simultaneously, and multiple climatic and non-climatic risks will interact, resulting in compounding overall risk and risks cascading across sectors and regions.’

Disasters have always been a systemic crisis for individual families in remote parts of Australia and for many local communities, disrupting livelihoods, income and infrastructure, with cascading impacts on health, education and other arenas. Three factors have made these disasters manageable. The first is the great resilience of regional Australians, resulting from long experience adapting to Australia’s often harsh conditions. The second is the outside financial and other support provided by state, territory and Commonwealth authorities to help residents cope with the disasters and rebuild their communities. The third is the fact that the most extreme of these disasters happen infrequently, giving communities time to replenish their resilience.

Climate change is upending all three of these factors. In Queensland, 55 of the 77 local government areas have recently experienced three or more major disasters in three years. For many, it has been four or five disasters. We’re also now beginning to see these systemic impacts emerge at the state-wide level. The year before the Black Summer fires, a record drought and extreme temperatures in Queensland contributed to the outbreak of fires that burned one million hectares, the largest expanse affected since recordkeeping began. The fires, together with the record flooding that followed, had enormous cross-sectoral, cascading impacts across the state.

And Black Summer vividly demonstrated that these systemic impacts are also now appearing on a national scale. The fires destroyed 24 million hectares, with unprecedented cascading health, biodiversity and economic impacts.

One very important implication of the systemic nature of climate disruptions ^[4] is that countries such as Australia will experience not just major domestic impacts but regional and global impacts as well. Indeed, the impacts from climate disruption occurring outside of Australia may undermine ^[5] our national wellbeing as much as or more than the domestic impacts.

The IPCC assessment warns that the global systemic effects will be profound:

Weather and climate extremes are causing economic and societal impacts across national boundaries through supply-chains, markets, and natural resource flows, with increasing transboundary risks projected across the water, energy and food sectors … In cities and settlements, climate impacts on key infrastructure are leading to losses and damage across water and food systems, and affect economic activity, with impacts extending beyond the area directly impacted by the climate hazard.

Most countries, including our own, have failed to grasp the significance of these emerging systemic impacts. This is reflected in the fact that national adaptation strategies are generally developed by bureaucratically weak environment ministries and focus almost exclusively on domestic climate impacts. Even the domestic focus is often siloed, with poor integration across bureaucratic areas. Climate adaptation planning, for example, is rarely integrated with disaster risk-reduction planning (which is generally led by emergency management agencies) despite the enormous overlap between the two issues.

If we could put on a pair of glasses that somehow magically enabled us to see climate risks, the risks wouldn’t fit neatly into bureaucratic, sectoral or organisational silos, but rather cut across them, including at varying temporal and spatial scales (from local to global). The glasses would instantly reveal the inadequacy of the silo-based climate planning conducted by most governments.

The gathering and intensifying climate risks must be addressed through a comprehensive process directed by the highest levels of government, using the best available climate and hazard information, and applying a framework that incorporates local, national, regional and global-scale risks, impacts and connections.

Conducting an Indo-Pacific climate and security risk assessment should be an important early contribution to a national climate risk assessment. It would also be an opportunity to identify joint initiatives involving the aid program and the region’s militaries, finance ministries, disaster management agencies, multilateral development banks and others to reduce the climate and security risks to our neighbours and, as a consequence, to Australia.

Most fundamentally, the latest UN climate assessment highlights the enormous stakes involved in preventing dangerous climate change. We have a limited window of opportunity to avoid the systemic climate disruptions the report says have already emerged, and the far more devastating ones to come if the climate warms to 2°C and beyond. This is a systemic challenge that requires a systemic response globally as well as here in Australia.