A sea change is gonna come

Change is all around us these days. There is no escape from it, and that applies to changes to the shimmering blue briny that is also all round us.

Think of change and it is mostly in relation to those things close by us, which can affect our communities, our lives and jobs, and our environment. It is also generally about transformations on land, which of course is where most of us live.

When we look out to sea, it just looks so vast, so constant and unchanging a force and feature of our world, that it is difficult to imagine it too could be changing significantly in ways that, until relatively recently, were either poorly understood or unknown.

If you zoom in closer, you can see the oceans are always in a state of flux, relentlessly swirling, pushed this way and that by weather and the shape of the land. But those changes are largely predictable and cyclic.

One day the sea appears grey and stormy, its angry waves flecked with white caps; the next it is a gently rippling aquamarine pool; the following, a mirror-like azure millpond. But the rhythms are always there — the waves keep rolling in and crashing on the shore, and the tides keep endlessly lifting and dropping the sea.

It’s the predictability of those patterns, the fact they happen no matter what else is going on, that makes the sea seem somehow inviolable and above it all. So it comes as an especially hard blow to find out mankind’s actions are now having significant effects on the salty marine engine that drives life on our planet.

This week, for a change, the news columns have been full of something different from Covid-19, the war in Ukraine, and moronic crime and violence. Instead, we have had the frightening prospects brought home to us about climate change-induced sea-level rise around New Zealand in the decades ahead.

In a massive and critical piece of work, scientists from the NZ SeaRise programme have projected likely sea-level rise up to the year 2300 for every 2km of the coast.

Led by Prof Tim Naish of Te Herenga Waka — Victoria University of Wellington and Associate Prof Richard Levy of GNS Science, the analysis takes into account land movement through subsidence and uplift, and the contribution of climate-driven sea-level change, to calculate probable local sea-level rises.

The new figures confirm previous guidance that for the highly vulnerable South Dunedin, sea-level rise of up to 35cm is likely by 2050-60, and possibly as much as 1.12m by 2100, but dependent on global greenhouse gas emissions.

The story is considerably worse for other parts of the New Zealand coast, particularly around Wellington and Wairarapa, where land subsidence due to tectonic action means sea level could rise by more than 1.5m by 2100.

The authors say global sea-level rise is accelerating, due to the expansion of warmer oceans and ice melt. On average the increase was 1.7mm per year from 1901 to 2010, but from 1993 to 2016 the seas rose at an average rate of 3.4mm a year.

Marine heatwaves, such as the one currently being experienced, are also changing what is in the seas around New Zealand. This week, the Moana Project warned that all coastal waters, except around Otago Peninsula, are in a state of heatwave and expected to stay that way for at least another week, with sea-surface temperatures at least 1degC above average.

No wonder then that the distribution of fish species in our waters is changing and unusual visitors are washing up on our shores. Warmer seas also mean it will become easier for tropical algae to invade and disrupt endemic ecosystems.

It may look the same out there as it always has. But a sea change is literally taking place — just another reminder of how humanity is wrecking the world.

Comments

All perfectly correct. However, i do not think that this will change matters much down at Forbury Park. Given the local smoke signals that have been emitted recently, I'll bet my boots that shortly a 'barely above current sea level' housing development for this site will be proposed by whoever, and then promptly approved by the DCC - who only a short time ago were announcing the imminent immersion of South Dunedin.

Water is a powerful solvent. Unfortunately,in some sitations, when the dollar goggles are on, it's not quite as powerful as money.

I know what you mean Rob but unfortunately nature is about to show us that our craven money grubbing ways are no match for her wrath.

Very few of the people alive today will be alive when these predictions may come into effect. Do we really care and do we want to sacrifice now for an unknown future? COVID has shown that many of the younger generation could not care less about protecting the elderly, so why should people be expected to give up self interest for future generations? They can look after themselves!

Did our grandparents not strive and fight wars to secure a better future (our present)? Are we going to be the first generation to bequeath our descendants a degraded life because we don't care?

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