Safe and sheltered, pleasant natural qualities including bird life, east-facing with good morning sun, the perfect suburban beach for the whole family… that’s how residents described Roches Beach, east of Hobart on Frederick Henry Bay, in a Clarence City Council resident survey last year.
The survey was instigated by the fact that the beach has been getting smaller. One respondent pointed to private homes whose back yards “go straight into the beach” so that a visitor “feels like an intruder walking on private land”. Another was fearful that a child playing on an eroded dune might be buried by a sand fall.
Another expressed annoyance at “property owners showing complete disregard and treating the dunes as if they own them”. For their part, property owners expressed fear at losing their homes to coastal erosion, one of them lamenting council money spent on a Bellerive boardwalk and New Year fireworks instead of protecting the coast. Criticisms included bad modelling, self-interested consultants, “sub-par” scientists and “incorrect measurements”.
One survey respondent commented that both council and community face “huge challenges in our lifetime and beyond”, lamenting that governments were failing to address those challenges. Another begged to differ: “The last community meeting that I attended in the Lauderdale Hall was more of a climate change scare campaign rather that the sharing of genuine… knowledge of the Lauderdale coastal erosion situation.”
There’s an underlying message here about the response of communities, governments and the world at large to the growing impact of climate change. When concentrated personal wealth is at stake, like a home, people will take in only what they want to and discard the rest.
Here’s what science says about the kind of climate change Roches Beach residents should be most concerned about. Hotter oceans and melting ice are accelerating sea level rise, from a 20th century average rate of 1.4 mm a year to about 4.7 mm a year in the decade to 2023.
At current warming rates the seas lapping Tasmania will be at least 20 cm higher by 2050 and a metre higher by 2100, but projections so far out are inevitably imprecise. A projection by a Singapore-based team published last week put the latter figure, globally averaged, at a “very likely” 1.9 metres.
Chris Sharples has spent many decades studying the interplay between land and ocean, a study whose focus has been sharpened by our changing climate and the rising global sea level. Last year he turned that lifetime of study into a hard-earned PhD based on a protracted study of the behaviour of the Roches Beach shoreline.
Sharples picked Roches Beach for his thesis topic because annual aerial photos from 1946 enabled a study of changing behaviour over many decades. What he discovered is that after being stable for at least four decades, in 1986 a major section of Roches Beach shoreline began to recede in a trend that only slowed from 2011, when Clarence City Council began replenishing sand at the dune front.
In a major research paper published last week in the prestigious international journal Marine Geology, Sharples and co-author Christopher Watson, also of the University of Tasmania, reported their finding that “the rising sea-level has increased the frequency and scale of upper beach erosion events, causing increasing net losses of eroded sand from the [Roches Beach] embayment”.
In career terms this is a significant moment for Sharples and Watson, his PhD supervisor. And though perhaps none of them know it yet, it’s more momentous still for Tasmania and the Clarence municipality – and especially for coastal residents of the Roches Beach-Lauderdale area struggling to get their heads around what’s happening to their beloved beach.
Many of these residents have for years felt a gnawing anxiety about their future. Some have found a sort of comfort in hearing or reading about other possible explanations for their predicament, but despite everyone’s best efforts that predicament has never gone away.
Now they have something unique among Tasmanian coastal dwellers. Thanks to decades of dogged effort by Sharples, their beach has been studied more intensively than any other part of our state’s 3000 km of coastline, and the finding is clear. They now know that the central, underlying reason for their disappearing beach is a rising sea level.
Certain coastal management measures may hold the seas at bay for a while, but in the long term the only way to stop the beach from receding is to lower the amount of carbon that we Tasmanians, all other Australians and everyone else in the world (especially the developed part) are putting up there. End of story.