Graham Easterling wrote:

On 21 Jan, 19:15, "Nick Gardner"
wrote:
There was a report on Spotlight (regional programme) the other day about
eroding cliffs and shifts in sand/pebbles on beaches etc.

The bit that caught my attention was when the presenter said that with
increasing global temperatures there will be an increase in the frequency
and size of the big waves rolling onto our beaches, thus increasing erosion.

I sent him an email saying that with the Arctic warming disproportionally
more than the tropics, that the temperature difference is decreasing and so
are the severity and frequency of the Atlantic storms reaching our shores.
He agreed with the disproportionate warming but not with the decrease in
storminess.

He pointed me to this
article:http://xtide.ldeo.columbia.edu/~visb...ster/Woolf.pdf.

The article seems to point at an increase, being no expert on these things
is there anybody who could cast a comment on this?

I seem to recall that Graham has some interesting data showing a significant
decrease in gales for the west of Cornwall.

Thanks in advance.
_____________________
Nick
Otter Valley, Devon
83 m amslhttp://www.ottervalley.co.uk

Yes, there is no doubt that there were less gales in Cornwall during
the 1st decade of this century than in the '90s, and significantly
less than was average over several decades before. I believe the same
is true in NW Scotland, Orkney & Shetland, suggesting it's not simply
due to the depressions following a different track, but being less
intense. (Though the number of severe damaging gales seems to be much
the same.)

Also the last Autumn/Winter certainly hasn't been a stormy one, and on
most local beaches locally the sand level is rather higher than normal
for the time of year.

The sand level on beaches varies significantly dependent on the recent
weather conditions. On many north Cornwall beaches it gets low after a
period of NW winds, but a strong SW wind often brings the sand back
in. A SE steepens the beaches. I remember last winter Spotlight did a
report on very low sand levels at Fistral (Newquay). after a spell of
NW winds. The sand level's high now, as it is at Porthmeor at St Ives,
few NW winds lately. That's not to say parts of the coast aren't
suffering serious erosion, but much of the report was, in my opinion,
complete rubbish.

I had a quick look at the link and it talks about an increase in wave
height. It is wrong to assume the bigger the wave the more erosive it
is. There has been a biggish swell of Cornwall recently, typically
6-10' on the north coast, but as the wind's been predominantly
offshore, the waves have been constructive rather than destructive. An
onshore NW gale with a smaller swell, but a big undertow, can be very
destructive.

I feel I'm drifting into Norman's area of expertise here, so I'll
stop!


Graham
Penzance


You carry on Graham. I tend to work in water that's a bit deeper than the surf
zone!

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.