When she was a kid in the Mallee in Victoria, Dr Julie Arblaster spent a lot of time outside, swimming in the Murray and roaming in the bush. Weather has always been an important part of her life, and these days it has become central to her profession.
Now an associate professor at Monash University’s School of Earth, Atmosphere and Environment, Arblaster works on huge models that run on super-computers to better understand the global climate, how it’s changing now and how it might change in the future. The often-unpalatable conclusions go to policy-makers to help them plan for an uncertain future.
“We know that greenhouse gases like CO2 trap heat and prevent it from escaping into space, we’ve known that for 150 years,” Arblaster says. “But we need to know how much that increase in greenhouse gases will warm the system and how rapidly it will warm, the consequences that warming will have, how it will change our rainfall patterns, how it might change heat-waves, and whether we can we reverse that warming.”
Understanding the extremes of climate change is crucial, she adds, because the resulting flash floods and crippling heat waves affect people’s health and wellbeing. “A one degree rise in average temperatures doesn’t sound like a lot, but it can have a really big impact on the extremes, like the heat-waves and the extreme rainfall events, that lead to the flooding we saw in Queensland a few years ago”, she says.
Although climate change has become a largely-accepted fact of life nearly everywhere, how best to deal with it is now a matter of global debate. Meanwhile Arblaster and her colleagues keep crunching the data from multiple sources to predict as accurately as possible what lies ahead in the years and decades to come.
“Because we’re moving into a regime that we haven’t seen for millions of years, in terms of the amount of CO2 in the atmosphere, the climate models are the best tools we have to understand the future changes”, she says.
Over time, the models have proved remarkably accurate. “They’re not perfect obviously, but the ones we were running 20 years ago gave projections for now that are pretty close to what’s happened,” Arblaster says. “If we want to stay below 1.5 or 2 degrees warming above the pre-industrial level, which is what all the countries signed up to in the Paris agreement, then we need to start reducing emissions as soon as possible.”