Climate Conversation Group

This post has been in the works for several weeks now but it hasn’t lost its fascination. A story appeared in the NZ Herald on 8 November about the latest sighting of icebergs, which annoyed me for its references to global warming. But on investigating I discovered some interesting science.

Icebergs are beautiful

Let’s do something for the language
There’s no collective noun for icebergs (the situation is worse than we thought!). Here are some suggestions: a group, a herd, a glide, a float, a thunder, sizzle, swish, a gleam, a crackle or a slush? That has a lovely rhythm. Let me know your preference, or send in your suggestions. When the list is a bit longer we’ll put up an online poll.

The story is stale and the icebergs have melted, but two issues remain: The first is that there’s nothing new about icebergs floating past New Zealand. It doesn’t happen often, but evidence proves regular visits going back millennia. Believe it or not, we have photographs! Not of icebergs exactly, but where they’ve been… well, you’ll see, read on.

The second point is that NIWA scientists can be relied on to mention the magic words “climate change” any time they’re talking about ice, water, wind or weather and that, my friends, makes me angry.

A petty, transparent little trick

It’s absurd to suggest that minor variations in temperature affect the fracturing of glaciers and ice shelves. The IPCC claims the average global temperature anomaly has increased about 0.6 °C over a hundred years. But polar ice is far more strongly affected by precipitation in previous decades, wind and wave action, water currents and distance past the grounding point.

Even in the deepest ice age, with the lowest temperatures and the thickest ice, the glacier or ice shelf must eventually snap as it floats further and further out to sea — it’s all about the mechanics. Half a degree of warming is meaningless in Antarctic temperatures.

The only reason to mention that global warming might be “blamed” is to keep us afraid of global warming; there’s no science in it, it’s just a petty, transparent little trick. Global warming cannot have caused anything abnormal because there has been no statistically significant temperature increase for 15 years.

But, back to the Herald story. Their description of the latest dramatic iceberg glide-by went like this:

A massive iceberg spotted southwest of New Zealand could be moving closer.

The iceberg was seen by Australian scientists working on Macquarie Island, who estimated it to be 500m wide and 50m high.

NIWA oceanographer Mike Williams said it was unusual to see icebergs in that part of the Southern Ocean.

A photograph in the Herald, snapped at Macquarie Island, shows the dramatic dimensions of the rectangular berg — half a kilometre long and towering 150 feet above the water! But then Mr Williams says something odd:

“The only precedent for icebergs being seen that far north is the one that came through in November 2006,” he said.

But he was recorded at the time saying it had happened before — in 1931. Has he forgotten?

In November, 2006, Maggie McNaughton reported in the Herald a giant flotilla of 100 icebergs passed just 260 km off the coast of the South Island. She quoted our Mike Williams, who said it was the closest recorded iceberg to New Zealand since 1931.

Why does Mr Williams contradict himself in his latest comments? Does he want to establish that something new and unprecedented is happening with the icebergs — could it be global warming, we wonder?

Of course, Mr Williams might have been misquoted; it happens. But in that case, which statement was the misquote? The latest story also mentioned:

Williams said it wasn’t clear whether climate change was to blame.

There you go, it’s climate change, the scientist said so. Even though he actually said he wasn’t sure it was climate change, it’s close enough for many people. So are the uninformed misinformed.

The earlier story quoted Auckland University glacial geomorphology lecturer, Dr Paul Augustinus, saying that it was unlikely to be related to global warming: “I wouldn’t like to speculate on the cause… It could relate to a number of factors such as the break-up of a larger iceberg.”

So Dr Augustinus was restrained in 2006, but it has now become obligatory that a scientist talking about anything which occurs outdoors must mention its relationship, real or imagined, with global warming.

Propaganda of the crudest kind

In the recent story Williams is simply saying they can’t link the icebergs with climate change. But if that’s true, why mention it at all? He can’t link the icebergs with the death of Michael Jackson either, but he doesn’t mention that. Neither can he link them with overfishing, the production of pinot noir or sunspots, but he leaves them out, too.

It’s nonsense — the reason he mentions “blaming” climate change is to make the link with global warming and keep the community fear level high. There’s no science in what he says — it’s political propaganda, which is what NIWA does these days. It’s a proper shame, because they have good scientists. Pity their managers are poor politicians. Anyway, it’s a good job that Kiwis are being fooled less and less by the anthropogenic global warming scare.

Some interesting science

NIWA have a very nice web page that informs us that icebergs have been making their way past New Zealand for millions of years. It says “Antarctica exerts an icy control on the waters flowing past New Zealand”. Colourful.

The writers explain that, as the clockwise Antarctic Circumpolar Current (ACC) circles Antarctica for 24,000 km, it encounters two prominent constrictions: the Drake Passage off South America and the submarine continent off New Zealand. These constrictions force the ACC to ride well north of its usual path (see inset map). There’s a beautiful graphic that I reproduce here; not everything in it is labelled and explained, but there’s enough to marvel over. It gives a wonderful birds-eye view of fantastic processes made magically visible.

Off southern New Zealand, the interaction between current and seabed is dramatic. As the ACC strikes the Campbell Plateau, large eddies form and migrate north along the plateau edge, stirring sediment in water depths exceeding 3000 m. Water as cold as 5 °C almost reaches Chatham Rise.

Icebergs carry cargo north

Crucially for our story, NIWA explains about the long history of icebergs moving up to New Zealand. How do they know this? Icebergs carry rock debris — they’re like gigantic natural barges. We might better liken them to oil tankers, as they carry far more cargo than the largest ships we’ve ever built. Stone doesn’t float, but nature has invented a method of transporting trillions of tons of the stuff across the water — who’d have thought?

During the ice age we had a connection with Antarctica in the flotilla of icebergs reaching New Zealand via the ACC. They floated up with their rocky cargo, which fell to the seabed as the ice melted. Analysis of this debris in sediment cores records repeated iceberg invasions over the millennia. Locally, the northern limit of iceberg invasion was the warm, shallow waters bathing the crest of Chatham Rise. Today, this crest is marked by grooves and pits gouged by entrapped icebergs, while the surrounding seabed is littered with unmistakable pieces of the Antarctic continent.

There’s an underwater acoustic survey image of an area off the west of the Chathams (see the red star on the inset map) showing scour marks in the seabed from giant stranded icebergs about 20,000 years ago (click to expand):

I love that image; it’s like a mere, or perhaps Maui’s fish hook, gouged there in the seabed. What a sophisticated imaging system — and it shows we need not fear the occasional iceberg appearing on the horizon, as it’s been happening for one heck of a long time.

By the way (in case you didn’t pick this up), it’s nothing to do with our emissions of greenhouse gases — having icebergs wandering by is entirely natural, controlled by wind and ocean currents.

With scientists blaming so many things on global warming, isn’t that a welcome change?