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"Sea rise risks for New Zealand?" Topic

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Early morning writer07 Oct 2015 5:14 p.m. PST

I'm working something up and would like any information relating to impact of global warming and sea rise on New Zealand. Especially impacts on Maori communities but overall and in general as well.

Thanks to anyone who can help!


Mark Plant07 Oct 2015 8:23 p.m. PST

Do you mean in the future, or in the past?

There are effectively no impacts from sea level as New Zealand isn't particularly low lying.

Moreover our sea level rise is more impacted by the rise of the plate (10 mm a year) on the East than the rise of the sea (3 mm a year). Where beaches are at issue the problem is erosion due to the strong sideways currents, which again over-ride the small sea level rise. Beaches and cliffs are eroded away faster than sea level can affect them.

The effect on Maori in the past would have been basically zero, other than kumara grows better in the warm, so long cool periods were hard for them because they couldn't grow kumara.

The actual amount of warming is much disputed, note. The evidence for much rise in the past is low. The NZ proxies don't show much dramatic happening. Not enough to dramatically change Maori lifestyles.

There is a suggestion that contact with the Pacific Islands was lost due to rougher seas during the cooling after the Medieval Warm Period. To believe that you have to believe in the MWP (which I do) but that contradicts the claim that there has been global warming.

platypus01au07 Oct 2015 8:49 p.m. PST

Major issue with sea-level rise is Port infrastructure. You may have to spend lots of money re-building your commercial ports, and posibly re-building them again, and again.

Napier may have a problem as well.


Mark Plant07 Oct 2015 8:56 p.m. PST

Sorry John, I rewrote my post because I decided that the OP meant in the past. (Otherwise the bit about Maori communities makes no sense.)

I agree that the only major effect in the near future would be rebuilding ports.

Andoreth07 Oct 2015 9:18 p.m. PST

One other effect may be in terms of refugees. A rise in sea levels in the Pacific could result in population pressures on the island groups such as Tonga leading to people seeking new lives and jobs elsewhere. New Zealand would be one of the closest places for people to relocate to.

Mark Plant08 Oct 2015 11:45 a.m. PST

Not Tonga, as it is not particularly low-lying.

Kiribati by contrast is largely atolls, and could potentially go under.

In fact atolls rise to match sea level (when not polluted) which is why all the atolls of the world are all just above sea level -- it's not some ridiculous fluke.

Despite the "loss of land" due to sea rise, the Kiribati are actually congregating on Tarawa, because they want modern amenities. Leading to massive overcrowding. (The same way Brazilians crowd into favelas, because a slum is better than the countryside). They will be pressing to come to NZ regardless of whether the water rises or not. It's a given.

Early morning writer08 Oct 2015 6:13 p.m. PST

We're all on islands, wherever we are, some just larger than others. And my interest is current day, not past history.

So, a different bit – how often does New Zealand get hit with full force cyclones – or is it too far south to ever take the full front of such storms?

Again, thanks for the input.

Whatisitgood4atwork08 Oct 2015 7:29 p.m. PST

From NIWA (National Institute of Water and Atmospheric Research).

'Recent NIWA research shows that northern New Zealand is hit by an average of a little over one storm of tropical origin each year. The severity of these storms depends on their location and on the phase of the El Niņo/La Niņa cycle. …'

TLDR version: not many, and most lose puff by the time they get here, but we do get the occasional doozie.


Mark Plant08 Oct 2015 7:40 p.m. PST

OK present day.

Sea level rise isn't much of an issue. When it makes the "scary" news it is about Auckland that has a little bit that is low lying and prone to flooding. And scare stories about the Pacific Islands.

Warming of a degree or two would be almost entirely beneficial to NZ, which has nowhere too hot and a south a bit too cold.

We never get full force cyclones, being far too far south. They have a tendency to arrive when half spent about once a year and dump enormous amounts of rain on the top half of the North Island. Sometimes that causes major flooding, although the country is pretty rainy at the best of times, so infrastructure is built for it and generally recovery isn't too bad. Much more Hurricane Sandy than Katrina.

Earthquakes and volcanoes are what we worry about.

Supercilius Maximus17 Oct 2015 8:29 p.m. PST

I've seen some computer models of serious earthquakes and land-slips on the western coats of South America; I'm guessing that these are deliberately "worst case", but none of them seem to end well for anyone living in Kiwi World.

Early morning writer19 Oct 2015 8:02 p.m. PST

Popping back in to avoid being remiss. Thanks to all for your input – seems I'll have to move my project to a more in danger zone. Though SM's little bit is worthy to consider but not quite right for what I'm working on.

So, Thanks!

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