It had been known for more than hundred years that increases in concentration were likely to warm the planet. So CSIRO commenced work on the modelling of the whole climate system. But in the 1980s it was realised that very few of our Australian colleagues, across a wide range of different disciplines, were either aware of the potential of global warming, or seriously considering, from their own perspectives, whether it was of any importance.
Senior Climatologist Dr Lynette Bettio explains that soon we will no longer be considering how we get through a single intense year, such as 2019, but how we can make it through a stretch of years with no respite. The climate has been set on a warming path – the long-lived greenhouse gasses that are in the atmosphere and the extra energy soaked up by oceans have secured the warming trend continuing for the next few decades. So the Bureau of Meteorology and CSIRO are investing a lot of effort to solve these problems, knowing the sooner we take action, the sooner we will see a divergence from the alarming projections in current climate models and simulations.
The UNFCCC Paris Agreement to combat climate change requires commitment and action towards a sustainable, low carbon future. The target set was to limit global warming to 1.5°C – and we are only 0.4°C away. Global carbon emissions peaked in 2019 but have already dropped down this year due to limited air travel and other factors. While the circumstances that brought about these changes are less than ideal, it is a start and hopefully lays the foundation for sustained reductions.
The future climate is in our hands – our actions now will decide that future. Energy production remains the primary driver of greenhouse gas emissions, followed by agriculture, forestry and other land uses, then industry and transport. According to climate scientist Professor David Karoly, countries in the Southern Hemisphere are expected to experience the largest economic impacts of global warming, and it is therefore imperative that Australia takes leadership and responsibility for making change.
The IPCC aims to understand the influences driving the Earth’s climate variability and future climate scenarios. It does not conduct its own research or run models; instead, it provides a meta-analysis of the work of thousands of researchers across the globe to provide a scientific basis for governments to develop climate-related policies. The IPCC warns of risks to food production and security, water availability, species extinction, biodiversity reduction, coastal erosion, floods and droughts, negative impacts on human health, and population displacement. ‘The IPCC has been saying the same thing since the 1990s, but no one is listening,’ said Dr Chloe Mackallah, reading directly from the IPCC’s Fifth Assessment Report, which states that the effects of anthropogenic greenhouse gas emissions ‘are extremely likely to have been the dominant cause of the observed warming since the mid-20th century.’
Current climate models cannot capture the persistence of drought and length of heatwaves, and they struggle to simulate future rainfall extremes, sometimes because they offer conflicting results, because climate prediction and greenhouse gas emission models are not just in the hands of climate scientists. They have to take the human population into account – demography, economics, technology, and our actions. The modelling of future carbon dioxide emissions provides multiple possible futures depending on these. Professor Andy Pitman asks “what do you want for your future? Which do you think we can achieve?”