Coastal winners and losers

... from sea level changes around Aotearoa

First, some good news, at least for people living in Dunedin ….

A consortium of scientists based at the University of Victoria recently released some promising news. Their new map of the New Zealand coastline shows areas of land uplift or descent due to geological processes like volcanism or the movement of tectonic plates. The blue shadings below show coastal areas where the land is sinking, and brown shows regions of coastal uplift.

NZ coastline map from the SeaRise Project at VUW.

If those trends continue, it’s good news for Dunedin, where the rise in sea level is now predicted to be slower than average because of continuing vertical uplift in the land. Parts of Dunedin are the most at risk in New Zealand from rising sea levels. The just-published study shows that the rate of land uplift there goes some way towards compensating for the 3.6 mm per year rise in sea level attributable to climate change. The news is even better further south in Rakiura (Stewart Island).

Unfortunately, that’s not the case for the country as a whole. There’s a lot more blue than brown on the map, showing that our country is gradually fading away even without climate change to hurry it along. The news is particularly bad for beachfront areas in Wellington, Auckland and Christchurch. These are among our most densely populated regions, and the subsidence of land there just adds to the problem. In Wellington, the sinking land effect is at least twice as large as the sea-level rise due to climate change.

There are regional winners and losers on our Shaky Isles.

And now the bad new for Dunedin ….

Despite the slight coastal uplift in Dunedin, sea levels is still rising, with the rate of increase in recent decades being much faster than in the first half of the 20th century when records first began, as shown by this plot from yesterday’s ODT. The overall rate of increase is about 3 mm/year, which isn’t much less than the national average.

Maybe not such a good news story after all …. Sorry about that.

We know the cause. You can do much more than buying an electric car and continuing to eat less meat.

Vote in mayors and councils who will do something about it, rather than hiding their heads in the diminishing sands.

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Thanks for reading this. Previous posts on the intersection between Ozone, UV, Climate, and Health can be found at my UV & You area at Substack.