The Australian areas that can expect to see more hailstorms
Hail severity will increase in most regions of the world while Australia and Europe are expected to experience more hailstorms as a result of climate change, an international review led by a UNSW Sydney researcher has found.
The review study examined the effects climate change will have on hail in the future.
It shows a global summary of hail trends from past observations and projected future trends from simulations and models.
The review led to the general expectation that hailstorm frequency will decrease in East Asia and North America, while increasing in Australia and Europe, and that hailstorm severity will increase in most regions.
"We came to the conclusion that on balance, the hail threat is likely to increase in Australia, especially in Australia's south-east including the Sydney area," lead author Tim Raupach said.
But the researchers say current and future climate change effects on hailstorms remain highly uncertain, in part due to a lack of long-term observations and limited modelling studies.
"There's very high uncertainty when it comes to these predictions and Australia is particularly of high uncertainty because there are very few studies that have actually looked at Australia.
"We need to do further study to find out exactly what we expect to happen, not only in Australia but across the world."
The study examined the expectation that atmospheric ingredients that affect hail - an unstable atmosphere, the melting of falling hailstones, and wind shear or differences in wind by height - would change with a warming climate and lead to less frequent but more intense hailstorms.
"We know with climate change that we are going to have more moisture in the atmosphere and that leads to more instability in the atmosphere, so we expect there will be more tendency for thunderstorms to occur because of this unstable atmosphere," Dr Raupach said.
Because the atmosphere will be warmer, the melting level - which is the height in the atmosphere below which ice begins to melt - will get higher, he said.
"So as a melting level gets higher, hail that forms high in the atmosphere and falls towards the ground has more time to melt and may indeed melt entirely before it gets to the ground, and you end up with no hail at the surface.
"The hail will be more severe when it does occur, because there will be more instability in the atmosphere which can lead to the formation of much larger hailstones. So when the hail does survive this extra melting, it will be larger and more severe when it does actually hit the surface."
What is the worst hailstorm you have ever witnessed in your area? Are you worried what more severe hailstorms will lead to higher insurance costs?