Climate science and water policy – how do we move forward?

Australia has world leading climate and water scientists, who disproportionately contribute to global literature and the work of institutions like the International Panel of Climate Change. Similarly, Australia’s credentials in water policy are well-regarded. Over the past 30 years we’ve managed to put (mostly) effective controls on how much water is taken from the environment, through caps that adjust year-to-year reflecting our variable climate. We’ve got mechanisms that allow water use to move to higher value uses, and our industries and utilities are highly efficient.  

And yet… the means by which we consider climate change in our water management and policy are fledgling at best. So, where to from here? 

Historically, matching risk appetite to climate was “easy”. We assumed the climate was stationary. We looked at how frequently particular events happened in the past, we assumed that frequency would be the same in the future and we made decisions that reflected our risk appetite (or in some cases the insurance industry made those decisions for us). We made water allocation decisions on the basis that we would always have enough water left over for critical uses in the event of the worst possible drought, and we assumed the worst possible drought looked like the worst drought we’d seen before. 

In eastern Australia, the Tinderbox Drought (2017-19) blew that approach apart. Conditions were so much hotter and drier than anything seen in the observed climate record (1900-now) that the system fell apart. 36-month inflows into Burrendong Dam were 72% less than the previous driest recorded period in 1937-1940.  

So we’ve accepted the climate isn’t stationary, but what is the worst-case scenario we now need to prepare for? The NSW Regional Water Strategies suggested that by 2070, a drought similar to the Tinderbox Drought could go from being a 1 in 1000-year event to a 1 in 50-year event. This would indicate that the “worst case scenario" we should prepare for is likely much worse. 

Preparing for such events would come with enormous costs – to the economy, society and the environment. It would involve keeping water in storages for longer in case of an event that is “plausible” but unlikely. It would require us to spend billions of dollars augmenting the water supplies of our cities and towns – building desalination plants, recycling plants and maybe augmenting dams – and bringing in permanent water restrictions to limit demand. Yet not doing so, could be catastrophic beyond imagination.  

Faced with these decisions a treasury boffin would likely ask the climate scientist – what is the chance of the bad thing happening. The honest answer is “I don’t know, but it could.”  

The weather forecast tells us what is likely to happen over the next week. Long-range forecasts or “outlooks” can provide an indication of whether the new few months are likely to hotter, colder, wetter or drier than average. Climate projections have skill at telling us how the climate might change over the decades ahead. But between 6 months and 10 years into the future, we don’t know what will happen. If anyone tells you they do, either call out their bullshit or become best friends with them, because if they’re telling the truth they have the ability to become the most rich and powerful person on Earth.  

The problem is, these are the timeframes where all the valuable decisions need to be made. How long does the water in this dam need to last? Will it run dry next year, the year after, or in five years? Do I start building the $3 billion desalination plant now? What rules should go in this water sharing plan for the next ten years?  

The atmosphere is chaotic. While scientific advancements will continue to teach us more about the world we live in and what we are doing to it, they won’t solve uncertainty. In fact, as climate models get more powerful, they are simulating more of that uncertainty and showing us more plausible futures that we need to consider.  

There are no simple answers these problems, but there are pathways forward. Key to all of them is a change in the way we think about water policy (and policy in general). We can’t put a set of rules in place for a decade and come back a decade later to see how we’ve gone. We need institutional and governance arrangements that facilitate more rapid adaptation. We DO need to have plans in place for plausible scenarios, even if those scenarios of low likelihood and even if they terrify us. We DON’T need to make every adaptation today. Good adaptations come with considered and pre-agreed triggers that see us avoid costs as long as we can, but no longer than we can afford to. Effective risk monitoring frameworks help us see those triggers coming. 

This approach to public policy requires courage, which will only be possible if our elected officials provide an authorising environment for that to happen, which also requires courage on their part. We’ve got to understand the scary things and discuss them clearly with the community. 

Science and policy need to be two sides of the same coin. Policy teams should have scientists in them – not just physical scientists, but social scientists who can help design and navigate pathways to change, and economists who can make compelling cases to do so. “Good science” should be recognized and rewarded as that which helps make better decisions – not just papers that get more citations in other papers. The age of science being published in journals, reviews and reports then being thrown over the fence for policy makers to do something about is old and tired. At least I’m tired of it. 

The first map below shows where most of Australia’s water comes from. The majority of the Australian landscape produces next to no runoff. Most of the water that fills our rivers (with the exception of Tasmania, the Tropics and a narrow strip of land in southwest Western Australia) comes from rain that falls along the Great Divide. The second map shows the trend in Australian rainfall over the past 53 years. You might notice a correlation.  

Before we consider the impacts of heat or what climate science says about future change, these two maps are enough to tell us we have a problem.