Understanding the impact of climate change on direct weather events

In late 2019, one of Australia's major commercial insurance companies, IAG, in collaboration with the National Centre for Atmospheric Research in the United States, released  a report outlining the increased severe weather which will occur as a result of climate change. The report models impacts at 1.5C, 2C and +/- 2 degrees Celsius and makes for better understanding of the direct weather events caused by climate change rather than the larger global impacts of melting polar ice, acidification of oceans, higher temperatures and mega storms.

The report should probably have garnered greater interest at the time of release given it was commissioned by a large commercial insurer. The overall tenor of climate debate in Australia and political dynamic would not have been conducive to ensuring it received sufficient attention.

Of note, IAG's perspective is "... the level of knowledge has now reached the stage where it is possible to make confident assessment of the impacts of climate change at larger scales and longer time frames with objective assessment of the associated levels of confidence.."  This, of course, contradicts those political naysayers who believe the evidence of climate change is still contestable.

The report provides key six assessments which are summarised briefly below and given events of the past few months, many of these assessments have been shown to be accurate -

1. While the frequency of named tropical cyclones in the Australian region, the proportion of the most destructive tropical cyclones has increased at the expense of the more weaker systems. Tropical cyclone risks are therefore expected to increase rapidly in south-east Queensland,  north-east NSW regional followed by coastal districts in Western Australia.
2. Intense short duration rainfall is expected to increase almost everywhere in Australia , resulting in more frequent flooding in urban areas and in small river catchments.  
3. Areas of large hail (2.0-4.9cm in diameter) and giant hail (>5.0cm in diameter) should progressively move southwards with a large increase in the risk to the regions inland from the Hunter River, southwards through the central and southern highlands of New South Wales and central to eastern Victoria.
4. The multi-day impacts of east coast lows on the south-eastern seaboard of Australia are expected to increase due to wind-driven rainfall ingress, flash and riverine flooding. 
5. Bushfire risk, as measured by the trends in fire danger indices is likely to increase in all locations nationally leading to more frequent and extreme events and longer fire seasons.
6. Sea level rise is expected to accelerate around the Australian coastline but at differing rates. It is notable that past assessments of sea level rise are lower than those that recent observations show.

In light of actual recent new data, the IAG report may yet prove to still under-estimate the full weather impact which will be felt sooner rather than later.

The report can be accessed at this link -
IAG - NCAR Severe weather in a changing climate report