When the waters start to rise, how will coastlines around the globe be affected? A clever mash-up of Google Maps and NASA data gives a graphic illustration of what could happen if sea levels rise by up to 14 metres.
George Murphy, who commented on my North Polar Meltdown post, asked if I knew of any maps showing what might happen to coastlines when sea levels begin to rise. He’d had difficulty finding any. I didn’t know of any either, so I did a Google search for nasa climate change maps and found a site put together by Alex Tingle. Located at flood.firetree.net, Alex has managed to combine Google Maps with NASA data to produce a zoomable global map that can display the extent of coastline submersion when sea levels rise, up to 14 metres above current levels. The image on the left shows how London would be afflicted if the river Thames expanded under the pressure of an additional 14 metres of water (click these images to go to the site and see the maps there).
The shaded blue areas on this image show how a significant chunk of eastern England — and a sizeable area of Holland — would disappear if the North Sea rose by 14 metres:
It’s not a perfect system, as Alex discusses at his blog — but it gives enough of an indication to give us all pause for thought.
My part of the world, the levels of north Somerset, has often been flooded in the past — notably, in 1607 — and this image shows how ravaged the area would be if sea levels rose by 14 metres. The shaded area closely coincides with the low-lying area that has been flooded in the past. Of course, when the land floods because of exceptionally high spring tides or crashing storm surges, the body of water subsides quite rapidly (though it leaves utter devastation in its wake, the effects of which last for many years). What this picture shows is the extent of the permanent loss of land that would occur if sea levels rose by 14 metres. My village of Banwell, about four miles inland from the current coastal town of Weston-super-Mare, will be nestling on the shoreline of the new coast. Weston itself will disappear. Worlebury Hill, just to the north of Weston, will become an island. Glastonbury, some ten miles inland, will also find itself all-but surrounded by water and accessible only by a narrow strip of land (currently the A39). Burnham-on-Sea will become Burnham-under-sea; the ancient settlements of Highbridge and Bridgwater — and many more villages and hamlets — will be no more.
Because of limitations in the way Alex has been able to overlay the NASA data on the Google Maps, they can only go up to an increase of 14 metres. This is probably more than enough for current needs — some say there’s going to be about one metre of sea level rise by 2100 — but if most of the ice on Greenland and the ice on the Antarctic continent were to melt away during the centuries to come, then a rise in excess of 25 metres is not out of the question.
And some estimate that if all the ice presently existing on earth melted, sea levels would rise by a staggering 70 metres.
It puzzled me for days — what caused an old aerial pole on a neighbour’s house to oscillate wildly on a seemingly windless day? The answer, it turned out, wasn’t UFOs, but an equally fascinating phenomenon with its explanation rooted firmly in the science of fluid mechanics.
I was genuinely baffled by the mystery of the vibrating aerial pole on my neighbour’s house, which I wrote up in a post a few days ago. The coincidence of there being a UFO sighting in the area on the same day seemed to suggest a connection, and I speculated about whether electro-magnetic field disturbances might be responsible. I posted links to my item in the Unknown Country Forum and on the Fortean Times Bulletin Board. It was in the discussion thread at the FT board that what I now believe to be the answer was suggested (by the appropriately named contributor “misterwibble”): a phenomenon known as Vortex Shedding.
Wikipedia has an entry on vortex shedding, together with an animation that shows what happens when a fluid in motion — such as water or air — meets a solid blunt object (including, as in our case, a cylindrical object):
Von Kármán vortex street animation, courtesy Cesareo de La Rosa Siqueira
The Wikipedia entry explains the effect in detail, including equations for working out how fluids of different velocities passing cylinders of different diameters will produce vortices possessing different qualities, but for our purposes, the animation is enough to make it obvious what is happening — as each vortex is spun off the leeward side of the cylinder, alternating on the left and right sides, pressure-drops are caused on the opposing side which pulls the cylinder first one way, then the other. If the frequency of the production of the vortices corresponds with the resonating frequency of the cylinder, the motion (oscillation) of the cylinder back and forth will be accentuated until, in some cases, the structure will fail.
Vortex shedding is something I’d never heard of before, but now I know about it, it’s the obvious answer. In the case of the aerial pole, only a very light breeze is necessary to make it oscillate because its (presumably) aluminium construction is so thin, as can be seen in this photo, looking up the pole from underneath. When the wind is blowing from east to west, as it has been when I’ve seen the pole oscillating, it’s blowing from directly behind the pole from my viewpoint and towards me, so the movement I see is left to right. At other times — say, when the wind is blowing from south to north — any pole oscillations would be back and forth from my perspective and therefore much more difficult to observe from a distance.
I was confused as to why the pole vibrates in light breezes but not when the wind force is higher. Vortex shedding provides an answer: the pole doesn’t oscillate in higher winds because the frequency with which the vortices are spun off the leeward side of the pole is higher than the pole’s natural resonating frequency, and so it doesn’t react in ‘sympathy’.
Finally, a few videos at YouTube put the icing on the cake, as it were: here’s a traffic light pole being affected by vortex shedding:
It’s never done it before, and it hasn’t done it since. A disused aerial pole on a neighbour’s house was observed to be vibrating in an unusual fashion on Tuesday 4th November 2008. What could have caused it?
This innocent-looking metal aerial pole (now disused — it’s minus the aerial) attached to my neighbour’s house (the owner was away at the time), which I can see clearly just beyond the bottom of my small garden, caught my attention as I gazed through the conservatory window on the morning of Tuesday 4th November.
The weather was overcast and there was hardly any wind — just light breezes blew from time to time. The pole, however, was acting as though it was in the teeth of a fierce gale, oscillating rapidly back and forth.
I drew Marcy’s attention to it, saying: “Now, what on earth could be causing that pole to vibrate like that?” We agreed that we’d never seen it doing it before. I’ve lived here five years, and Marcy lived in the house next door for 24 years before I married her and dragged her here next door in 2005, and she’d never seen anything like it either.
A little mesmerised by it, I opened the conservatory door and stood on the patio to get a clearer view. By now I had been observing it for about three minutes, and though it was not vibrating as fiercely as it had been when I first spotted it, I was amazed that it was still doing it at all — the wind, such as it was, hardly had the strength to move the nearby leaves on another neighbour’s silver birch trees, let alone affect a sturdy metal pole of about an inch diameter. Clearly, the movement couldn’t be put down to the wind alone. There were no unusual noises to be heard, no vibrations to be felt through the ground, and no other aerial poles within sight were behaving this way. Everything else seemed normal.
Mystified, I watched until it died down completely. “Well, I don’t know,” I said as I stepped back into the conservatory. “The only thing that comes to mind is that it was responding to some kind of electro-magnetic field — it resonated with the frequency of whatever the field might be. Perhaps a UFO’s passing overhead above the cloud cover,” I added jokingly.
A few hours later at around 2pm, Marcy had gone out and I wandered back into the conservatory to have another look.
The pole was doing it again — vibrating as fiercely as it had been during the morning. This time I grabbed my phone and videoed it. Here’s the result, posted to YouTube:
It’s not the clearest video in the world, but the pole can be seen oscillating. (By the time I’d got my phone and started videoing, it was calming down again.)
The next day, Wednesday, weather conditions were about the same. I watched for any pole activity. There was none. In fact, at this time of writing, there’s been no activity (that I’ve seen) since Tuesday.
Then on Thursday came some interesting news that got me thinking. The Sun newspaper carried a story about two Bristol women who had used their camera phone on Tuesday evening to video what they said was a UFO with several lights (or maybe it was several separate UFOs) over south Bristol — about 18 miles from where I live. Apparently their video shows what wasn’t visible to the naked eye at the time: the UFO(s) were occasionally shooting red and white beams of ‘light’ down to the ground.
Under the headline What’s Zap? the story reports that A RED beam of light shoots to the ground from what is believed to be a UFO. The Sun was yesterday handed dramatic footage of the mysterious craft hovering over Bristol.
Shellie Williams, 20, and her mum Betty, 53, filmed it on their mobile phones. When they zoomed in, they also caught red and white vertical beams not visible to the naked eye. Care worker Shellie, who watched from outside her home in nearby Hartcliffe, said: “It was bizarre and I was quite frightened.” Betty said: “Through binoculars you could see clusters of lights. They seemed to form a circle and were attached to something. It freaked us out.”
Neighbour Tony Jefferies said he had seen the lights on and off for two weeks. In daylight yesterday, Shellie and Betty pinpointed the lights as being close to a radio mast on Dundry Hill. Air traffic control at Bristol International Airport said it had no reports of “unusual activity”. Avon & Somerset police said their helicopter was not out and they had not had UFO reports.
Here’s the Sun video, which has been posted several times now on YouTube:
Videos of this nature are always very hard to assess. There’s no real frame of reference, it’s jumpy, and it’s night-time. I’m sure Shellie and Betty would swear that they simply videoed what they saw with their own eyes, only discovering the red and white beams on playback, and I have no reason to disbelieve them. My video is just as poor — but it has the saving grace of having been filmed in daylight, and there are reference points such as the house and the nearby trees to give it scale. And I give you my word that I, too, simply videoed what I saw with my own eyes.
As a point of interest, another UFO was photographed on the Friday before (31st October), over Filton, near Bristol. It was reported on the This Is Bristol web site on Monday November 3rd. Taxi driver Paul Matthews spotted the object in the air near the Royal Mail Depot at 2pm on Friday afternoon. Mr Matthews said that at first he thought it was an aeroplane, microlite or parachute, but it wasn’t behaving like anything he had seen before. “It was very weird. It was so strange. I have been a lorry driver in my time and seen some strange things, but this is something else,” said Mr Matthews, 45, from Patchway. “I had never ever seen something like this before. I was really surprised how other people had not noticed it. I thought they would be stopping in their droves, but that was not the case at all.”
My purpose here isn’t really to present an analysis of the Sun video or the Filton UFO photograph, but if I were assessing them without having observed for myself the aerial pole going crazy, I’d probably say the red and white beams on the video look a bit suspect, and the photograph, on a closer view, looks something like a construction of light canvas or paper over a wire or balsa wood frame.
However, my observation of the strangely oscillating pole gives me pause for thought. Try as I might, I can’t think of any ‘rational’ explanation for its behaviour. The most obvious answer would be the action of the wind — but there was hardly any at the time, and in any case such a pole, carrying a hefty TV aerial (which it used to do until about two years ago), would have been chosen to resist high winds. Without the aerial fixed on top, the pole on its own would offer even less resistance to strong winds. (I’m waiting for a windy day so I can observe it under those conditions.)
I’ve wondered if perhaps there was a vibration coming up through the ground — something like infra-sound caused by minor earth tremors. (We do get them in Britain from time to time.) But again, even if I couldn’t feel them through the soles of my feet, I would have thought other aerial poles, or even our washing-line carousel, would have trembled at the same time, or buildings would have creaked with the movement. And the length of time the pole vibrated on each observation — at least five minutes, I would estimate — seems to rule out infra-sound from earth tremors or nearby heavy works or quarry explosions further afield.
I keep coming back to a non-physical cause, such as an energy field of some kind, presumably electro-magnetic in nature. The pole, being a particular length (I believe it’s a hollow cylinder) and being of a certain metal density and diameter, could have possessed just the right properties to ‘receive’ the particular frequency of energy that was being ‘transmitted’ in this area at the time. I think of a ferrite rod in an old transistor radio for comparison — the ‘length’ of the rod being effectively altered by the mechanical tuning mechanism moving a surrounding wire coil up and down the rod to tune the radio to differing frequencies. The hollow construction of the pole might also have served to magnify the effect of the energy being inducted into it.
No-one knows for sure what propulsion systems UFOs use, but it would not be out of the question for them to utilise some sort of electro-magnetic field generator that repulses the Earth’s magnetic field to give them the lift they need to stay aloft.
Perhaps my neighbour’s old aerial pole is, in effect, a UFO detector!