Antarctic Peninsula ice shelves Ice shelf collapse on the Antarctic Peninsula Rifting on Larsen C Impact of calving the large iceberg Sea level rise following ice-shelf collapse References Comments Antarctic Peninsula ice shelves The Antarctic Peninsula is fringed by floating ice shelves. They are floating extensions of the glaciers on land, and receive mass by snowfall and marine freeze-on. They lose mass by melting at their base and by calving icebergs. Larsen C Ice Shelf, the largest ice shelf on the Antarctic Peninsula, is currently being closely watched.
Beckman, and Terence J.
Without the availability of the historical documentary records the long-term variability of the Sun implied by the Maunder Minimum would not have come to light, and the consequent advances in stellar physics and in palaeoclimatology would not have been possible.
One familiar factor is the effect of solar activity on short-wave radio communications. During sunspot maximum high-energy protons and alpha particles from the Sun affect the ionosphere, reducing its effectivity as a mirror from which short radio waves are reflected round the world, disrupting transmissions for days at a time.
The association with the presence of large numbers of dark spots on the solar disc is widely known, and well understood, and it is also clear that such maxima repeat every 10 or 11 years, with minima between them.
More specialized is the knowledge that this cycle was discovered only some years ago by Schwabeand put on a firm observational basis during the last century by Wolfand subsequent papers, summarized in Waldmeier If this is accepted as true, it has strong implications for our ideas of how magnetic fields in stars are produced.
Of more impact, it might go some of the way, even all of the way, to explaining the observed pattern of global warming of the Earth in the last decades of the 20th century.
Following the decision of the panel at its 43rd Session to accept the invitation from the UNFCCC, at its 44th Session, the Panel approved the outline of Global Warming of °C, an IPCC special report on the impacts of global warming of °C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of. Project Information Project % Complete Major Supported Platforms: Search for extra-terrestrial radio signals at [email protected] On July 25, , the project owners began releasing work units for [email protected]'s Astropulse project. The project passed 2 billion credits on July 14, Human Rights Violations in Syria - Syria is going through a civil war. A civil war is a war with the same country inside their country. Stephen Starr says that the Civil war is between the Sunni Muslim Rebels and most of Syria's 2 million Christians under the rule of Bashar Assad.
Since it would not have been possible to study solar phenomena in the 17th century without the appropriate records, the importance of such records in this case ought to be readily apparent.
The reason for the remaining discussion is to give sufficient detail to show how well founded in fact is the proposition that sunspot activity was virtually absent for some 70 years during the period cited.
If there are doubts due Outlines for global warming research papers inadequacy of the record these can only serve to reinforce the importance of maintaining complete archives in the general case, and any debate within our presentation is confined to the climatic significance of the findings, rather than dealing with the relevance of archive material, which we regard as obvious.
Sunspots in the late 17th Century: Evidence of Absence, or Absence of Evidence? We now know that aurorae are caused by sub-atomic particles emitted by the Sun during releases of magnetic energy which often accompany sunspots. Much later, Maunder found a note by Flamsteed, the first Astronomer Royal, describing a sunspot seen at Greenwich inin which Flamsteed says that it is the first he had seen since Flamsteed made several other references to this spot and to his solar observations in general in his correspondence, the definitive edition of which is now nearing completion Flamsteed This scepticism, first propounded by Herschelwas pressed strongly by Luby ; both claimed that the main reason for few reports of sunspots from to was that people were not observing the Sun, or at any rate not systematically.
Eddy set out to show that this had not in fact been the case. Flamsteed was also a persistent solar observer between and He found less than 50, whereas in any typical year interval during the past hundred years there have been between 40, and 50, spots reported.
As well as the low levels of activity beforethere are well attested reports, notably by La Hire in France and Derham in England, of the surge in sunspot activity which occurred during and after that year, in which sunspots returned to the solar surface in the quantities which we take to be normal today.
Indirect supporting evidence for the absence of activity in the late 17th century, and of its resurgence in the early 18th century, comes from the record of auroral sightings. By his paper in Science, Eddy succeeded in convincing many researchers that there was real evidence for the sunspot absence in the Maunder Minimum period and incidentally coined the term Maunder Minimum by which the period has become known, and which proved a neat sales slogan.
His article did add some interesting extra touches, such as an attempt to show that the solar corona at eclipse during the period was strongly suppressed compared with its present exhibition of major streamers.
He also looked at the tree-ring 14C record, using the hypothesis that in the absence of solar activity the high energy cosmic rays which produce 14C in the atmosphere penetrate to circumterrestrial space in greater fluxes, being less repelled by the solar wind.
One would expect higher levels of 14C in rings formed during sunspot minimum, at the present epoch, and a fortiori in rings formed during the prolonged Maunder Minimum.
He claimed that the Maunder Minimum coincided in time with an era of colder weather, and that by implication the absence of magnetic activity was accompanied by a net fall in the total radiative output of the Sun.
An implicit corollary is that in the intervening period the radiative output has been increasing, with a consequent warming of the Earth. One should be wary of jumping to conclusions about the role of greenhouse gases in our atmosphere in procuring a generalized warming of the Earth, given the great complexity of physical processes inherent in the reaction of the atmosphere-ocean system to a change in atmospheric transparency, knowing that such a change is in fact occurring as a result of the emission of gases in industry and transport.
To this area of doubt the advocates of solar global warming have been able to add their element of confusion. Maybe we are experiencing a steady rise in the solar constant, accompanying a similar rise in solar magnetic variability, and maybe the greenhouse effect is not the main agent, or even a cause, of global warming.
The novelty of the use of the Maunder Minimum in this context is the hypothesis that the time-scale associated with any change may be of order hundreds rather than tens of years, which would be the scale for changes directly linked to individual or year cycles.
Magnetic Cycles in Late-type Stars: Wilson sic began a long-term study of magnetic cycles in cool stars using as his observational indicator the variable emission flux of the H and K resonance lines of ionized calcium whose appearance in emission is characteristic of stellar chromospheres.
There is an excess of H and K emission in the faculae which surround sunspots, and epochs of sunspot maximum coincide with epochs of maximum H and K. Wilson set out to see whether stars of similar spectral type and luminosity class i.
This entailed a major project, the monitoring of the fluxes of a group of stars during decades. A full summary of the project and its results is given in Baliunas et al.
One of the manifold implications of these results is the possible detection of Maunder minima in Sun-like stars. Again, in general terms, the older a star the slower it rotates. In a cluster these effects can be cancelled even at a single epoch by averaging over its population, but for a single star this is not possible.The Strongbow Saga follows the adventures of Halfdan Hroriksson, a young Dane, across the Viking world of the latter half of the 9th century, weaving his fictional tale in and out of actual events of the period and the lives of the historical figures who shaped them, combining a fast moving, gripping story with an accurate portrayal of the Vikings and their world.
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