Asian tsunami: is there a climate change connection? 04 January 05

I’m glad you don’t make any connection, between the Asian tsunami and climate change, because there simply isn’t one. There are people out there who like to claim ‘we’ blame everything on climate change. ‘We’ don’t.

On a slightly different tack I see the shocking death toll represents only a few days worth of human birth globally. Amazing.

Mark raises an important question. As Peter says, ‘we’ shouldn’t be seen as overstating ‘our’ case for the anthropogenic contribution to climate change, nor of the contribution of climate change to the earthquake that caused the tsunami. However, on the other hand, we should not be shrink from exploring the possibility of a link between the tsunami and what humans are doing to the global climate, solely because it is easy to ridicule the suggestion. The earth’s systems are far more complex than we understand – possibly than we can ever understand. Some of the most powerful computers in the world are deployed in meteorology, but they still can’t tell us whether we’ll have rain tomorrow.

Here is a letter that was published in The (Melbourne) Age on 30 December. In the spirit of Mark’s and Peter’s caution, note that the writer is not claiming that climate change caused the tsunami, only that there are possible links.

“It is no coincidence that a Richter scale 8.1 quake near Macquarie Island between Tasmania and Antarctica was followed just days later by the catastrophic one in the Indian Ocean off the Aceh coast.

“Both are on the boundary of the India-Australia tectonic plate, and shocks and stresses from the first would have contributed to the one that followed.

“And a factor in the Macquarie Island earthquake would have been the redistribution of load on the planet’s crust as Antarctic ice melts due to global warming.

“As the climate warms, and more Antarctic ice melts, the countries on the boundary of our plate – New Zealand, New Guinea, Indonesia and southern Asia – can expect more and bigger earthquakes”

This WAS a ‘letter to the editor’, so the writer deployed hyperbole; nevertheless, he presents an hypothesis that is worth exploring. Unfortunately, I know nothing of the physics of Earth’s tectonic plates so have no way of judging the merits of that hypothesis.

On another matter, it was 74,000 years ago that Mt Toba erupted at a site very close to the 26 December quake. This quake sent so much dust and ash into the atmosphere that it caused a six-year nuclear winter and a thousand year instant ice-age, reducing the planet’s human population to a tenuous 10,000 in number.

See: http://people.colgate.edu/ehirshorn/geol220/interactions.htm (and many others)

It is speculated that glaciation may have reduced sea levels at that time, reducing the pressure on Toba and allowing it to erupt.

So, we could be looking at a legacy of the Toba eruption, but there is no doubt in my mind that the origins are complex and multi-causal, with timescales we are unaccustomed to handling.

Interestingly, the US Geological Survey doesn’t agree with the letter-writer that there is any connection between the two earthquakes.

Here’s what they say:

“The occurrence of two great earthquakes within such a short space of time is indeed striking. However, even in retrospect, we do not yet see evidence for a strong causal relationship between the two earthquakes.

It seems clear that long-term stress changes associated with one earthquake may trigger other earthquakes on the same fault or on nearby faults. In fact, the aftershocks that occur around the source of a large earthquake are triggered by such stress changes. But the long-term stress changes caused by an earthquake decrease rapidly with distance away from the earthquake source. The Macquarie Ridge earthquake was very far from the site of the yet-to-occur Sumatra-Andaman Islands earthquake, and occurred on a different plate boundary. The hypothesis that long-term stress changes associated with the Macquarie Ridge earthquake triggered the Sumatra-Andaman Islands earthquake therefore does not seem compelling.

There is also strong evidence that the shaking of the ground caused by a great earthquake, such as the Macquarie Ridge earthquake, can trigger small earthquakes in sensitive tectonic environments at large distances from the great earthquake. The evidence for such triggering is most convincing when the earthquakes that are thought to be triggered occur near the time of strongest shaking from the triggering earthquake, which would be within several hours following the triggering earthquake. However, the Sumatra/Andaman-Islands earthquake occurred about two-and-a-half days after the Macquarie Ridge earthquake.

An alternative to the hypothesis that the Macquarie Ridge and Sumatra/Andaman Islands earthquakes are causally related is that the occurrence of the two, widely separated, great earthquakes within three days was a probabilistic coincidence.”

They also address the question of why the Macquarie Ridge 8.1 earthquake didn’t produce a tsunami:

“A tsunami is a sea wave of local or distant origin that can be generated when the sea floor abruptly deforms and vertically displaces overlying water. Such a displacement can occur when an earthquake ruptures oceanic lithosphere. When the opposite sides of a fault are inclined and have a vertical component of motion, we have an earthquake with dip-slip faulting. When the opposite sides of a fault are vertical and move horizontally, we have an earthquake with strike-slip faulting. Given two earthquakes of the same size, the one that has greater vertical fault motion is likely to displace a greater amount of overlying water. Indeed, the Sumatra and Macquarie Ridge earthquakes occurred on different plate boundaries and had different faulting mechanisms. The Macquarie Ridge forms part of the Pacific-Australian plate boundary and the faulting mechanism of this earthquake is predominantly strike-slip. The Sumatra earthquake occurred on the interface of the India and Burma plates and its faulting mechanism was predominantly thrust with vertical slip.”

(from http://earthquake.usgs.gov/eqinthenews/2004/usslav/neic_slav_faq.html”

o Oreskes has clarified her comments and states that VOA has misquoted her.

o Is the vice-speaker of the Duma a climate scientist?

o Of course the contrascientists are going to town on this issue, painting all environmentalists with the same broad brush. One should be very careful with this issue.

Best,

D

Yes, the VOA press release did seem a bit dumb. I’ve never heard of the Duma guy, but according to this article (which attacks the supposed attempts “by a wide array of environmentalists and scientists” to link the tsunami with global warming) Arthur Chilingarov is a “Russian scientist” who is “is the vice speaker of the State Duma and co-chairman of the organizational committee that is planning the International Polar Year in 2007”. But since most of the rest of the article is rubbish, this may not be true either.

First of all: HOORAY! I’m on the message boards! I’ve had problems with getting on here, and now, here I am! Thanks, Mark, for getting your guy to fix things. Hope it lasts….

As to the disaster, it most likely is natural. Still, tsunamis aren’t normal in the Indian Ocean. Yet.

The sea water levels around the world are UP, in part because of GW. Even if GW/CC didn’t play a role in THIS disaster, it’s a likelihood in the future. And if THIS disaster is seen as “natural,” what will an UNnatural disaster be like?

I shiver….

...is not melting.

the edges are melting a little further back during the summer months than in the past, but that is all. The overall actual continental ice mass is increasing. I’m not sure if it is at a slower rate than in the past, but the point is, it’s not shrinking.

also…newer theories are out there debunking a lot of our long held supositions on plate tectonics. In short, we don’t really know what’s happening down there. We sometimes can tell when somethings going to happen(basically as the event starts, we say, “somethings going to happen!”), but that is all.

thanks,

john metevier

The Antarctic ice sheet is not uniform. Half the continent is warming, half is cooling. It is a big continent.

Generalizations such as ‘the ice sheet is not melting’ are incorrect.

HTH,

D