You may have heard the 'moon wobble' will intensify coastal floods. Well, here's what that means for Australia - The Conversation AU

Many coastal towns and cities in Australia would already be familiar with what are known as “nuisance” floods, which occur during some high tides?

A recent study from NASA and the University of Hawaii suggests even nuisance floods are set to get worse in the mid-2030s as the moon’s orbit begins another phase, combined with rising sea levels from climate change.

We know average sea levels are rising from climate change, and we know small rises in average sea levels amplify flooding during storms.

From the perspective of coastal communities, it’s not if a major flood will occur, it’s when the next one will arrive, and the next one after that.

But we know from historical and paleontological records of flooding events that in many, if not most, cases the coastal flooding we’ve directly experienced in our lifetimes are simply the entrée in terms of what will occur in future.

This means for some years during the 18.6-year cycle, some high tides are higher than they would have otherwise been.

This results in increases to daily tidal rises, and this, in turn, will exacerbate coastal flooding, whether it be nuisance flooding in vulnerable areas, or magnified flooding during a storm.

A major wobble amplification phase will occur in the mid-2030s, when climate change will make the problem become severe in some cases.

The triple whammy of the wobble in the moon’s orbit, ongoing upwards creep in sea levels from ocean warming, and more intense storms associated with climate change, will bring the impacts of sea-level rise earlier than previously expected — in many locations around the world.

The locations in Australia where tides have the largest range, and will be most impacted by the wobble, aren’t close to the major population centres.

However, many Australian cities host suburbs that routinely flood during larger high tides.

Near my home in Meanjin (Brisbane), the ocean regularly backs up through the storm water drainage system during large high tides.

In high-income nations like Australia, sea-level rise means increasing unaffordability of insurance for coastal homes, followed by an inability to seek insurance cover at all and, ultimately, reductions in asset values for those unable or unwilling to adapt.

The prognosis for lower-income coastal communities that aren’t able to adapt to sea-level rise is clear: increasingly frequent and intense flooding will make many aspects of daily life difficult to sustain.