This is reported at the UIUC site. Included is this:

"One week after dipping below 4 million square kilometers Northern
Hemisphere sea ice area and setting the new historic record NH sea ice
minimum, there is currently 3.58 million sq. kilometers sea ice area. This
new minimum is almost 11% lower than the previous historic minimum. "

Taken from

http://arctic.atmos.uiuc.edu/cryosphere/

There are still a few weeks of melting before the autumn freeze starts.

--
Mike Tullett - Coleraine 55.13°N 6.69°W posted 21/08/2007 09:56:20 GMT

Mike Tullett wrote:

This is reported at the UIUC site. Included is this:

"One week after dipping below 4 million square kilometers Northern
Hemisphere sea ice area and setting the new historic record NH sea ice
minimum, there is currently 3.58 million sq. kilometers sea ice area. This
new minimum is almost 11% lower than the previous historic minimum. "

Taken from

http://arctic.atmos.uiuc.edu/cryosphere/

There are still a few weeks of melting before the autumn freeze starts.



Any idea why the measurement of the area of ice is so different as that at
NSIDC - 5.26? They both agree it's a record but can't agree on the value.
NSIDC tends to overestimate the amount of ice - it still shows ice in
Hudson Bay and Siberian rivers, for example - but I don't see this as being
enough to account for the difference.


--
Graham P Davis
Bracknell, Berks., UK
Send e-mails to "newsman" as mails to "newsboy" are ignored.

On Tue, 21 Aug 2007 12:06:34 +0100, Graham P Davis wrote in


http://arctic.atmos.uiuc.edu/cryosphere/

There are still a few weeks of melting before the autumn freeze starts.


Any idea why the measurement of the area of ice is so different as that at
NSIDC - 5.26? They both agree it's a record but can't agree on the value.
NSIDC tends to overestimate the amount of ice - it still shows ice in
Hudson Bay and Siberian rivers, for example - but I don't see this as being
enough to account for the difference.

I can only think they are measuring different percentages of ice cover. Do
you have a ready to hand link to what you are seeing at NSIDC, as I find
that site particularly hard to navigate?

--
Mike Tullett - Coleraine 55.13°N 6.69°W posted 21/08/2007 11:19:59 GMT

Wonder if it's the sea ice melt that's pushed the Jet Stream further south
than normal this summer


"Mike Tullett" wrote in message
...
On Tue, 21 Aug 2007 12:06:34 +0100, Graham P Davis wrote in


http://arctic.atmos.uiuc.edu/cryosphere/

There are still a few weeks of melting before the autumn freeze starts.


Any idea why the measurement of the area of ice is so different as that
at
NSIDC - 5.26? They both agree it's a record but can't agree on the value.
NSIDC tends to overestimate the amount of ice - it still shows ice in
Hudson Bay and Siberian rivers, for example - but I don't see this as
being
enough to account for the difference.

I can only think they are measuring different percentages of ice cover.
Do
you have a ready to hand link to what you are seeing at NSIDC, as I find
that site particularly hard to navigate?

--
Mike Tullett - Coleraine 55.13°N 6.69°W posted 21/08/2007 11:19:59 GMT

Mike Tullett wrote:

On Tue, 21 Aug 2007 12:06:34 +0100, Graham P Davis wrote in


http://arctic.atmos.uiuc.edu/cryosphere/

There are still a few weeks of melting before the autumn freeze starts.


Any idea why the measurement of the area of ice is so different as that
at NSIDC - 5.26? They both agree it's a record but can't agree on the
value. NSIDC tends to overestimate the amount of ice - it still shows ice
in Hudson Bay and Siberian rivers, for example - but I don't see this as
being enough to account for the difference.

I can only think they are measuring different percentages of ice cover.
Do you have a ready to hand link to what you are seeing at NSIDC, as I
find that site particularly hard to navigate?


Sorry Mike. I'd originally included a link to the relevant page but it got
lost in some re-editing. See
http://nsidc.org/news/press/2007_sea...810_index.html

--
Graham P Davis
Bracknell, Berks., UK
Send e-mails to "newsman" as mails to "newsboy" are ignored.

On Wed, 22 Aug 2007 07:59:27 +0100, Graham P Davis wrote in


http://arctic.atmos.uiuc.edu/cryosphere/

There are still a few weeks of melting before the autumn freeze starts.


Any idea why the measurement of the area of ice is so different as that
at NSIDC - 5.26? They both agree it's a record but can't agree on the
value. NSIDC tends to overestimate the amount of ice - it still shows ice
in Hudson Bay and Siberian rivers, for example - but I don't see this as
being enough to account for the difference.

I can only think they are measuring different percentages of ice cover.
Do you have a ready to hand link to what you are seeing at NSIDC, as I
find that site particularly hard to navigate?


Sorry Mike. I'd originally included a link to the relevant page but it got
lost in some re-editing. See
http://nsidc.org/news/press/2007_sea...810_index.html

I found the following hidden away in the NSIDC pages:

"ice extent
the total area covered by some amount of ice, including open water between
ice floes; ice extent is typically reported in square kilometers."

I can only think then that the UIUC site has a higher threshold for ice
cover. They do indicate :" there are some differences between the way we
and NSIDC process our sea ice indices." but don't really elaborate on it.

Whatever the source though, this is a remarkable year. The NSIDC site
usefully goes into the reasons for this year's rapid melt.

--
Mike Tullett - Coleraine 55.13°N 6.69°W posted 22/08/2007 12:06:41 GMT

On Wed, 22 Aug 2007 13:06:41 +0100, Mike Tullett wrote in


I found the following hidden away in the NSIDC pages:

"ice extent
the total area covered by some amount of ice, including open water between
ice floes; ice extent is typically reported in square kilometers."

It seems 15% may be the ice cover percentage, going by this graph at the
NSIDC site.

http://nsidc.org/news/press/2007_sea...timeseries.png

--
Mike Tullett - Coleraine 55.13°N 6.69°W posted 22/08/2007 12:16:02 GMT

Mike Tullett wrote:

On Wed, 22 Aug 2007 13:06:41 +0100, Mike Tullett wrote in


I found the following hidden away in the NSIDC pages:

"ice extent
the total area covered by some amount of ice, including open water
between ice floes; ice extent is typically reported in square
kilometers."

It seems 15% may be the ice cover percentage, going by this graph at the
NSIDC site.


http://nsidc.org/news/press/2007_sea...timeseries.png


My forecast three months ago of a record low has come good - or bad,
depending how you look at it - and the next challenge is to say when the
Arctic ice will disappear completely during the summer. The most
pessimistic forecast I've seen is that it will happen by 2040. However, my
feeling is that that's still too optimistic. The graph at
http://arctic.atmos.uiuc.edu/cryosph...rrent.anom.jpg shows an
accelerating decline. Also, the 40% loss in ice-thickness reported a while
ago was for the period 1965-95. As global temperatures had not started
falling until about 1975, I presume the 40% loss occurred after that year.
40% loss in twenty years and it's been getting warmer since then! Most of
the rough (very!) calculations I've made come up with 2020 as the likely
year when the ice goes. The next challenge is to be sure to live long
enough to see it!

--
Graham P Davis
Bracknell, Berks., UK
Send e-mails to "newsman" as mails to "newsboy" are ignored.

Graham P Davis wrote:

My forecast three months ago of a record low has come good - or bad,
depending how you look at it - and the next challenge is to say when the
Arctic ice will disappear completely during the summer. The most
pessimistic forecast I've seen is that it will happen by 2040. However, my
feeling is that that's still too optimistic. The graph at
http://arctic.atmos.uiuc.edu/cryosph...rrent.anom.jpg shows an
accelerating decline. Also, the 40% loss in ice-thickness reported a while
ago was for the period 1965-95. As global temperatures had not started
falling until about 1975, I presume the 40% loss occurred after that year.
40% loss in twenty years and it's been getting warmer since then! Most of
the rough (very!) calculations I've made come up with 2020 as the likely
year when the ice goes. The next challenge is to be sure to live long
enough to see it!


That is quite a scary concept.
--
Keith (Southend)
http://www.southendweather.net
e-mail: kreh at southendweather dot net

Keith (Southend) wrote:

Graham P Davis wrote:

My forecast three months ago of a record low has come good - or bad,
depending how you look at it - and the next challenge is to say when the
Arctic ice will disappear completely during the summer. The most
pessimistic forecast I've seen is that it will happen by 2040. However,
my feeling is that that's still too optimistic. The graph at
http://arctic.atmos.uiuc.edu/cryosph...rrent.anom.jpg shows an
accelerating decline. Also, the 40% loss in ice-thickness reported a
while ago was for the period 1965-95. As global temperatures had not
started falling until about 1975, I presume the 40% loss occurred after
that year. 40% loss in twenty years and it's been getting warmer since
then! Most of the rough (very!) calculations I've made come up with 2020
as the likely year when the ice goes. The next challenge is to be sure to
live long enough to see it!


That is quite a scary concept.

The latest from UIUC yesterday (http://arctic.atmos.uiuc.edu/cryosphere/) is
that the area is now down to 3.22 million sq. kilometres.

NSIDC (http://nsidc.org/news/press/2007_sea...810_index.html)
has also been updated and has interesting information on the North-West
Passage. One niggle I'd have with it though is it says "the region is more
open than it has ever been since the advent of routine monitoring in 1972."
Actually, it's been monitored for longer than that. In the late 60s and
early seventies it was monitored using satellite data and through that
period and earlier there were aircraft recce flights over the area. The Met
Office published charts from 1959 onwards and, although data-coverage is a
bit sketchy in the early years, it is still sufficient for me to say that
the passage is more open than in any year since those publications began.

On the same page, there is an animation of the disappearance of old ice from
1982-2007. It was my estimate that there'd been a stronger than average
outflow of old ice from the Arctic during the winter and spring that led me
to expect that this summer would see a record minimum in Arctic sea-ice
coverage.

--
Graham P Davis
Bracknell, Berks., UK
Send e-mails to "newsman" as mails to "newsboy" are ignored.