Bye-bye beaches

By October 1, 2020Science

Several years ago, I travelled to the Gold Coast in Queensland and stayed in a motel just behind Main Beach, and at high tide I had to stand with my nose almost plastered against the window of my room to see the sand on the beach, it had retreated so far. Indeed, we were able to get down to the beach in only a few places because so much sand has been washed away that at the back of the beach, just below our motel, was a 3 metre high sand cliff with dangling grass and shrub roots. Shoot forward to a few weeks ago and I was in Sydney, staying at Narrabeen. The beach was only accessible nearby at the local surf lifesaving club, because they had dumped sand in front of it to form a ramp to allow club members and the public to get down the beach. In most places the back of the beach was a sand or boulder cliff, with collapsed lawns and dangling ends of fences hanging over the precipice. On the beach below where I was staying, half way between the cliff and the water’s edge was a hemisphere of concrete with a fencepost sticking out of it. The ocean always wins.

More than half of Earth’s freshwater resources are held by the Antarctic Ice Sheet, and it represents by far the largest potential source for global sea-level rise under future warming conditions. The stability of the ice sheet determines the fate of our coastal cities1  and our beaches. It would be comforting to think that if we stopped producing greenhouse gases some time soon, then the Antarctic ice sheet will return to stability and all will be well. This would firstly require the relationship between global temperature rise and the melting of the ice sheet to be linear (i.e. 2 degrees rise in temperature would lead to twice as much melting as a 1 degree temperature rise would). In addition, it would require the climate to have little or no inertia. Unfortunately, feedbacks between the ice sheet, the atmosphere and the ocean are nonlinear1, and the climate has a great deal of inertia2. A new paper in one of the world’s premier scientific journals, Nature, has shown that the Antarctic Ice Sheet has several temperature thresholds beyond which ice loss is irreversible1.

In their paper in Nature, the authors have found that for global warming levels around 2 degrees Celsius above pre-industrial levels (we are already at 1 degree)3, West Antarctica is committed to long-term partial collapse owing to the marine ice-sheet instability. The ice sheet’s temperature sensitivity is such that we are committed to 1.3 metres of sea-level rise per degree of warming up to 2 degrees above pre-industrial levels (as I say above, we are already at 1 degree), almost doubling to 2.4 metres per degree of warming between 2 and 6 degrees and increasing to about 10 metres per degree of warming between 6 and 9 degrees. If we get to 6 degrees of warming, sea level rise will be the least of our worries. Each of these temperature thresholds gives rise to what is called hysteresis* behaviour; that is, the currently observed ice-sheet configuration is not regained even if temperatures are brought down to to present-day levels. In particular, for the West Antarctic Ice Sheet to regrow to its modern extent, we would need to decrease global temperatures to at least one degree Celsius lower than pre-industrial levels (i.e. 2 degrees below current levels). Their results show that if the Paris Agreement, to keep global temperature rise to 2 degrees or less, is not met, Antarctica’s long-term sea-level contribution will dramatically increase and exceed that of all other sources (e.g. Greenland). So, a 2 degree rise in global temperature will see a 2.6 metre rise in sea level, and many coastal towns and cities will suffer and many beaches will disappear completely.

*Hysteresis: the phenomenon in which the value of a physical property lags behind changes in the effect causing it.




  • Yes Minister says:

    Despite global warming being recognized as an extremely serious issue by almost all sentient beings, there is absolutely no will to do what needs to be done. It is fashionable to throw rocks at the lying nasties (and with good reason), but in reality no political faction is fair dinkum about change. In particular, one would expect the greens to be leading the charge but they prefer to advocate for open borders and effectively unlimited population growth, Meanwhile, the sheeple are incapable of seeing past short term self interest. I have no confidence that enlightenment is even possible, at least not before Gaia gets a lot more dramatic. IMO, it will take total destruction of coastal communities, wholesale deaths in the streets because of fifty plus temperatures, weeks long power outages or something comparable before the masses revolt. The virus kerfufffle is merely a warning that if not heeded will be followed by increasingly severe events. To my way of thinking, that is inevitable as long as neo-liberalism holds the reins.

    • admin says:

      I was on Twitter a while ago and had a discussion with a person who was of the opinion that the pandemic would not kill too many people, whereas I was of the opinion that it would likely kill millions. He scoffed and he said ‘get back to me in December’. I fully intend to do so. I was basing my opinion on what happened in the Spanish Flu pandemic of 1918-1920. That was estimated to have killed about 50 million people, and while I hope that does not happen this time, I think human stupidity will assist it in killing as many as possible. I agree with you that neoliberalism is behind this all. It has led to the increase in disparity between rich and poor, which has led people to be more susceptible to scapegoating, which has led to the election of halfwits like Trump, Johnson, Morrison, Bolsonaro etc., and it is their inability to cope with reality or heed science that has exacerbated the toll of Covid-19 and Climate Change.

  • Russell says:

    Just before I noticed this major post by admin, I was watching a television show; the third in a trio focusing on the (YUK) Murdoch dynasty – its few decent deeds and its huge pile of nasties. Near the end of this final segment about the Murdochs, well-known press gallery Methuselah on the right of centre at least, Paul Kelly, was asking the world’s number 2 Ultra-Liar what was more challenging, more important to consider for us in Australia. He gave Rupert a choice between our economic direction into the future, or climate change. Dorothy Dixer if ever there was one! Never had I heard Mr Moloch express anything personally on the second issue until tonight. It didn’t surprise me that he opted to view our economy’s (joke, LOL) “competitiveness” as THE matter of great concern. By the way, as soon as foolish Kelly mentioned that “C” thing, I nearly leapt up. I thought: “What competitiveness does Kelly think exists even now, let alone worrying to find a niche of opportunity in future years?” It was telling that he ignored that we are in our awful economic mess largely because successive governments failed again and again to shove or cajole us out of a dismally inadequate one-track minerals (coal, iron, gold, copper etc) economy. Australia is actually NON- competitive if one looks at the likes of Singapore – rather, we’re a standing joke. It’s hard to find even two or three major tertiary production ideas or some novel invention where Australia registers a shudder on the economic Richter Scale internationally; meaning: we have a financially sound export industry from it, and are recognised as in the forefront. We’ve lost our edges in so many fields of industry and commerce decades ago, from complacently having so narrow a vision of our potential, and by discouraging progressive people with inventions. They soon waltz off to other lands to make a huge profit out of large-scale production. We’ve ignorantly been killing off a gaggle of geese that might have laid a few golden eggs in OZ.
    However, worse than Kelly’s odd question was a pack of rubbish Murdoch babbled, as he tried to find inside his ageing brain some remote detail concerning the world climate issue. Putting it bluntly, our press magnate was unintelligible and so off-target,. it was pathetic to see him. Any figure he grabbed at was all guesswork and, of course, was wrongly used. No matter, in the end he said, all is fine and dandy climate-wise. In a dumb-and-dumber comment illustrating Murdoch’s gross lack of care about climate at all, he said that the general global temperature could continue upward by 3 degrees Centigrade WITHOUT MUCH NOTICEABLE EFFECT AT ALL! How comforted I felt suddenly.! If he says it, I must believe it. Mind you, I should have well expected such an inane response. After all, he knows and we know, that he will be long buried by the time five plus metres of water from Earth’s massively melted ice caps, causes humanity grave harm. As one writer on the global ice topic said in the very title of his text on the tipping points for speed of melt, “The water WILL come”. We slowcoach, lemming-like humans are basically doing almost zero now, to prevent ice-sheet collapse by year 2100. Are we mass suicidal?

    • admin says:

      As it seems from the scientific papers, one of which I quote in the article, we have at least 2.5 metres of sealevel rise which we will not be able to avoid, even if CO2 emissions were stopped immediately. Like most estimates these days, it is likely to be a gross underestimate, and that coupled with the increased intensity of storms, will make may seaside towns and cities dangerous places to live. As a joke some time ago, I said that in a few hundred years we may be able to visit the Great Barrier Reef from the port of Kyogle in norther NSW. It mightn’t be too far off the mark, if anyone remains.

  • Jim says:

    Apart from the impact of climate change one of the problems along coastlines is that people and governments do not realise, or happily ignore, that sea level has only been at its present level for about 6,000 years and that the coastline in many places is yet to come into equilibrium after the 130 metre rise in sea level from about 18000 to 6000 years ago. For example, in the Adelaide area there is a pronounced south to north longshore drift of sand with about 50,000 cubic metres of sand going past any given point per annum. This means that the southern beaches are continually eroded and if it was not for the construction of series of pipelines and trucking, the southern beaches would be totally denuded by now and the nearby roads and buildings would be in trouble. It has been suggested that if allowed to go to completion the coastline of the southern Adelaide beaches would finish up about a kilometre further inland. The natural state of affairs was interrupted permanently due to European settlement in 1836. Building of houses, roads, etc on coastal sand dunes, construction of breakwaters, boat havens, etc always leads to problems which are very expensive to sort out. Another case is on the Gold Coast–it is worth looking up “Tweed River training walls” on Google. Basically as soon as man interferes with the coastline there are problems, usually expensive ones. None of this stuff is rocket science and has been known for many years.

    • admin says:

      Interesting stuff; however, your use of the word permanently is probably a little optimistic given the rate of expected sea level rise. When we were up at the Gold Coast, I used to have a chuckle at the ship (presumably a dredge or a tender to one) going up and down down the coast all day every day, transporting sand dredged from the estuary down the the rapidly eroding beaches.

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