Thursday, March 28, 2024

Up the creek, but not without a paddleboat

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Steve Wyn-Harris explains why the weather is having such a blast.
The Hunga Tonga–Hunga Ha’apai eruption in 2022 propelled a record-breaking amount of water vapour into the Earth’s stratosphere.
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The wonderful thing about making new year predictions is what are the chances that anyone will remember in a year and even if they do, will they trouble themselves to hold you to account?

But you can never be too sure, so it’s best to predict certainties or leave some vagueness around the forecast. It works well for economists, horoscope writers and futurists.

I can tell you that the wet areas will get drier, and the dry areas will get wetter. At a point sometime in the future.

One of the best climate forecasts I saw last year was by Rob Sharpe, the Sky News Australia Meteorologist.

He turned out to be right on the money.

Back in October I read a piece by him saying that although La Niña was waning, don’t expect the massive amounts of rain in parts of Australia and here in New Zealand to come to an end.

I’d found this particular piece because I was searching to see if the Tongan volcano eruption had resulted in our wettest winter in my career. 

It was a year ago on January 15. Those here at the house heard the sonic boom of the eruption but I was on my motorbike on the farm and annoyed to have missed this epic sound from so far away.

The volcano went off with the force of about 100 Hiroshima nuclear bombs. Because the volcano was under the water but not so deep (150m) that water pressure suppressed its power, the superheated sea water became explosive steam and headed into the upper reaches of our atmosphere.

It seemed logical that if this eruption had ejected 50 million tonnes of water into the atmosphere, the old adage of what goes up must come down comes into play.

They reckon about 4 million tonnes of this went so high that it escaped gravity and went into space, which has never been observed before. That space water vapour even influenced a thing called the equatorial electrojet, which normally runs west to east in the ionosphere but reversed direction because of the water.

But I was wondering about the other 46 million tonnes up there, and was that why I spent much of the year in gumboots and leggings and am still wearing them in January?

Well, the volcanic event may very well have contributed to our record rainfalls and may still be in play with the continuing rain.

The southern hemisphere has had 20% more water in the stratosphere than before the eruption.

Some of that water vapour has formed clouds and fallen back to earth. That makes sense.

But there are other factors in play as well.

For a start, the event put a lot of extra energy into the atmosphere, creating more turbulence than usual and thus more storm systems.

The extra water vapour up there has had a slight increase on global warming but because Antarctica has had a blanket of extra water vapour over it reflecting sunlight back into space, the Antarctic has been colder than usual.

This chilly air has increased the polar vortex, which means the powerful westerlies have stayed closer, swirling around Antarctica, and means southern Australia and NZ have had fewer cold fronts and less wind.

This means the east coasts of both Australia and NZ will end up with more onshore winds bringing extra wet weather.

The meteorologist has been right so far and did say back in October that this would continue through the summer.

Time will prove whether he gets this right as well.

I’ll tell you one other strange and impossible-to-predict outcome of the Tongan eruption bringing more onshore conditions on this coast.

Before Christmas I was out at one of our local beaches.

I thought I could spot an overturned dinghy in the surf and rushed off to see if anyone needed help.

No sign of any people so I dragged the craft out of the surf and up onto the beach.

It wasn’t a dinghy but a paddleboat like you see at resorts.

Others find useful things like craypots and buoys, but this must be a unique bit of beachcombing.

I got the ute and had quite a struggle getting it onto the back and strapping it down.

We asked around the local beaches and no one reported missing one, nor had ever seen anyone with one in the sea.

It had small mussels growing on it so had been in the ocean for a few weeks.

I googled to see if some fool had gone missing during an attempt to cross the Pacific on a paddleboat or if anyone was reporting one lost, but nothing.

My best guess is that it had blown off a superyacht or cruise ship.

The only thing broken was the rudder, so I jury-rigged one and the local kids had great fun over Christmas and the New Year on the estuary.

I ordered a new rudder from Texas on New Year’s Day for US$50 and an eye-watering $50 to FedEx for delivery. You get what you pay for because it arrived in an astonishing six days despite New Year shutdowns and covid-disrupted deliveries.

Nearly everyone else at the beach has a fishing boat but I’m the only one with a paddleboat.

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