Former Gippslander Scott Hamilton* recently gave a brief interview on Tickernews about two of Antarctica’s melting glaciers – Pine Island and Thwaites glaciers – and gave a worst case sea level rise of “about 3 metres”. These glaciers alone are currently contributing about 10% of the global sea level rise. According to science, approaching tipping points would greatly increase their melting and lead to the 3m rise.
Scott stated that both ‘tipping points’ and ‘feedback loops’ were important in the Pine Island melting – the latter part of a more general warming as ice sheets retreat and exposed water absorbs more heat leading to more warming. See more on feedback lops here. But it is the tipping point that is the crucial point in the ‘worst case scenario. There are many analogies about tipping points – such as the ‘humpty dumpty’ nursery rhyme and the ‘straw that broke the camel’s back’. Retired CSIRO scientist Barrie Pittock likened tipping points to slowly pushing a light switch – which in this case is the gradual melting – and then the switch jumps to a completely new state. Then the glaciers melt rapidly at an increasing rate and, unlike the light switch, there is no return.
I have written frequently about sea level rise and its effects on Gippsland (see here and here for examples) in the last ten years. Other related aspects make the problem more complex and severe. Such factors include coastal erosion and deposition, Bruun’s rule and coastal retreat, and importantly storm surge, wave heights and tidal influences.
We are already witnessing both massive coastal erosion and deposition at Inverloch. There are a number of other coastal towns in Gippsland where a one metre rise, let alone three metres, will be disastrous including Lakes Entrance and Paynesville with the spring high tides flooding and undermining shops and houses, roads and other infrastructure. With a three metre rise there will be massive erosion, and coastal retreat along the Ninety-mile and the Gippsland Lakes will almost certainly disappear.
Unfortunately, humanity has left it far too late to stop the predicted sea level rises. Inertia in the climate systems means that sea will continue rising for many, possibly hundreds of, years. The current rock barrage installed at Inverloch to protect the coastal road is a temporary solution. We should be planning for an orderly retreat from all vulnerable areas of the coast. We should also be electing emergency governments whose primary goal is to stop emitting greenhouse gases and reduce them as rapidly as possible if we are to restrict global warming to two degrees.
* Strategic Advisory Panel Member, Australian-German Energy Transition Hub, University of Melbourne