Oceanography
Arctic Ice August 2011
In the days of sailing ships and the early days of steam, even into the early years of the 20th century, much of the Arctic remained inaccessible due to the extensive pack ice.
When explorers attempted to penetrate the ice, it is often found from their journals that they did so in late August. There are many references to be found of an 'open season' during which it was possible to maneuver a ship through an open lead during a period which was often only of two weeks duration, or less. In some years, the ice simply did not open as expected, and the explorers…
Arctic Ice July 2011 - Update
Are we headed for another 2007 style crash ?
In my Arctic Ice March 2011 - Update #1, I gave these figures for September minimum -
an extent below 4 million km2 is highly probable.an extent below 3 million km2 is entirely possible if Arctic weather continues to follow the overall trends of the last decade.
In April I revised that, based on some projections from IARC - IJIS figures to -
I project an end of season extent range between 3.9 million km2 and 4.5 million km2.
Here is today's graph :Sea ice extent July 21 2011image source: http://www.ijis.iarc.uaf.…
An unusual number of destructive storm surges along the East Coast during the 2009-2010 El Niño winter could be a taste of things to come - with more destructive storm surges in future El Niño years, according to a new study by NOAA.
El Niño conditions are characterized by unusually warm ocean temperatures in the Equatorial Pacific that normally peak during the Northern Hemisphere 'cool season.' They occur every three to five years with stronger events generally occurring every 10-15 years. El Niño conditions have important consequences for global weather patterns, and within the U.S., often…
New research on Jakobshavn Isbrae, a tongue of ice extending out to sea from Greenland's west coast, shows that large, marine-calving glaciers don't just shrink rapidly in response to global warming, they also grow at a remarkable pace during periods of global cooling. Glaciers change.Through an analysis of adjacent lake sediments and plant fossils, the researchers determined that the glacier, which retreated about 40 kilometers inland between 1850 and 2010, expanded outward at a similar pace about 200 years ago, during a time of cooler temperatures known as the Little Ice Age.…
Arctic Ice July 2011
For much of the written history of the Arctic, exceptional extents of open water were reported in terms of what the explorer, fisherman, whaler or sealer had previously experienced. That would make such events likely every 20 to 30 years. However, for each report of open ice in a specific area there is likely to be found in the archives a report from 180 degrees opposite across the pole of a greater than usual ice extent.
Within recent decades, and especially in the 21st century, we constantly see reports that total ice extent is the lowest, 2nd lowest or 3rd…
A new study shows that the rate of sea-level rise along the U.S. Atlantic coast is greater now than at any time in the past 2,000 years - and a consistent link between changes in global mean surface temperature and sea level.
They found that sea level was relatively stable from 200 B.C. to 1,000 A.D. During a warm climate period beginning in the 11th century referred to as both the Medieval Climate Anomaly and the Medieval Warming Period, sea level rose by about half a millimeter per year for 400 years. There was then a second period of stable sea level associated with a cooler period, called…
_I'm a little bit late in my linking, but the Carnival of the Blue is up for May! Huzzah! I've enjoyed following and occasionally contributing to this monthly compilation of ocean blogging. Sad to say, next month will probably be its last. In the words of carnival curator Jason Robertshaw,
Next month will be the last edition of the Carnival of the Blue that I will be curating. The consensus among those I've polled is that the utility of blog carnivals has diminished in the last couple of years, especially with the rise in social media. Consequently, June may also be the last Carnival of…
The Sea Isn't Level
In all discussions of sea level it is absolutely vital to keep in mind at all times that the sea is a very dynamic ravenous beast that wants to devour your coastal lands.
In passing, if you know that your land is likely to be gone in a few years, find yourself a mug punter and sell quickly. Despite all the evidence - the rapidly growing evidence - that the average global sea level is rising at an accelerating rate, find yourself someone who is so convinced that it ain't happening that he thinks beach front property is a sound financial investment.
Where land at the…
Nares Ice Bridge Breakup
The ice bridge in Nares Strait at the Kane Basin outlet to Baffin Bay has begun to break up.
There was a plug of consolidated ice solidly wedged across the channel. Consolidated ice is very strong in compression, but weak in tension, as I have noted in other articles, such as Bridges That Build Themselves. From that article:
... the arch begins to fail. It fails from combined causes. Edge erosion from melting changes the distribution of forces. Eventually the forces are unbalanced enough to generate resultant tension or shear forces which…
An Arctic Decade 2001 - 2011
For thousands of years the Arctic has been covered in perennial ice with seasonal changes at the margins and some natural variation, seen as losses and recoveries of extent.
For hundreds of years observers have noted that seasonal and local variations at the margins can leave some relatively small regions ice free one year, and solidly iced up in other years.
Since about the middle of the 19th century, explorers were able to slowly expand our knowledge of areas which had previously been entirely inaccessible due to the continued presence of old, thick ice. …