Ungrounded Australian Fears

From Watts Up With That?

Guest Post by Willis Eschenbach

In his recent post entitled Aussie Sea Level Rise Building Permit Chaos, Eric Worrall discussed how people in southern Australia are being prevented from building seaside structures due to fears of sea level rise.

So I thought I’d see what the data has to say. There are not a lot of long-term tide gauges in southern Australia. Here’s a map of their locations.

Figure 1. Long-term southern Australian tide stations. SOURCE: NOAA

Here’s a look at the data. All of these are from the source above.

Figures 2 [1-6]. Tide gauge records at the stations indicated by the green arrows in Fig. 1

Given all of those, just how fast is the sea level rising around Australia? Figure 3 shows that result, in units of sea level rise per century.

Figure 3. Historical sea level rise rates, all long-term southern Australia stations

Gotta say … I don’t see anything there to worry about.

“But … but … but what about the dreaded acceleration in sea level rise they’ve been warning us about for forty years!!”, I hear you thinking.

Well, to start with, look at the actual records above … see any dangerous acceleration there? Because I sure don’t.

Next, I’ve discussed sea level rise in detail in my posts Inside The Acceleration FactoryMunging the Sea Level DataProxy Rates Of Sea Level RiseScience Catches Up With WUWT, and The Uneasy Sea. Basically, what’s happening is that the rate of sea level rise periodically oscillates between acceleration and deceleration. Here, from The Uneasy Sea, are the thirty-year trailing acceleration of three global sea level records, along with the trailing acceleration calculated from long-term station trends.

Figure 4. 30-year trailing acceleration, by dates of the end of the 30-year periods.

As you can see, the rate of sea level rise regularly accelerates, with no overall acceleration. Does this extend to the Australian sea levels as well? Here’s the same data, for the Sydney tide gauge.

Figure 5. 30-year trailing acceleration of sea level rise, Sydney Fort Dennison tide gauge.

As with the data in Figure 4, the rate of sea level rise in Sydney Harbour has repeatedly varied between acceleration and deceleration. And the variations in Sydney match reasonably well with the global data.

However, the Sydney data in Figure 5 goes up to the end of 2021, compared to around 2017 in Figure 4 … and in the last few years, the change in the rate of sea level rise has gone from acceleration to … well, about zero.

The fact is that despite general warming over the last 120 years or so, and despite endless warnings of dire sea level rise drowning cities, there has been no overall acceleration of the rate of sea level rise. And as a result, the most reasonable prediction for the future is a continuation of the past, as shown in Figure 3 … in other words, the Aussies can stop the auto-flagellation and get back to building by the sea.

My regards to all from rainy Northern California,


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