The subduction zone that could lead to the closing of the Atlantic Ocean

Recent research carried out by geologists from the Monash University in Australia has revealed the beginnings of an active plate margin that could lead to the closing of the Atlantic Ocean, as it pulls the Eurasian and North American plates back together.

This research, led by João Duarte, involved mapping the seafloor off the coast of Iberia and has led to the discovery of a 186 mile long subduction zone in the Atlantic Ocean, 120 miles from Portugal. Put simply, the Earth’s crust consists of a number of tectonic plates, which move across the surface of the mantle, driven by convection currents deep within the Earth.  When two plates collide, the denser plate subducts underneath the other, which is less dense, forming a subduction zone.

The newly discovered subduction zone is not yet fully developed and is instead in ‘an embryonic’ stage, in the words of Duarte. The crack that is forming in the ocean floor will lead to the Eurasian splitting into two parts, one continental and one oceanic. The denser Oceanic section will then subduct underneath the Continental plate, leading to the Atlantic Ocean shrinking as North America and Europe are pulled together. Eventually, the two continents will be joined together and the resulting collision will lead to a new mountain range forming and a supercontinent, similar to Pangea, could potentially develop. This process will not be a fast one and the first significant changes will only begin to manifest themselves after roughly 20 million years. In approximately 220 million years the Atlantic Ocean should have closed up completely.

Scientists have been mapping the Atlantic Ocean seabed near Portugal for many years now for signs of potential tectonic activity and this discovery marks the first significant evidence that a subduction zone is indeed forming. The area has experienced relatively regular earthquakes, the most destructive of which was the 1755 earthquake, which had an estimated magnitude between 8.5 and 9. The primary impact of the earthquake and the series of tsunamis that were created by the seismic energy combined to destroy an ill-prepared Lisbon, killing 60000 people. It is predicted that earthquakes will become more common and increase in magnitude in the area around the subduction zone as it develops.

The discovery of this newly forming subduction zone, could contribute significantly to the field of plate tectonics, as further monitoring will allow for a greater understanding of how subduction zones initially form and the way in which supercontinents develop as oceans disappear. Duarte has suggested a possible cause behind this being that the subduction cycles of the African and Eurasian plates, which were previously being driven into one another, have subsided, resulting in the mountain ranges stretching from west to east across Europe and into Asia. There is existing evidence for this idea, as when the plates in the Pacific began to decrease in movement, two subduction zones, similar to one seen of the coast of Portugal, formed, one in the North Atlantic and the other near Antarctica.

Despite the fact we will never see the impacts of this subduction zone, as is inevitable with most geology and plate tectonics, it is fascinating to see how the series of supercontinents that have formed over time were made and how they broke apart, with this discovery in the Atlantic Ocean shedding new light on the field.

Contributed by James Axton

Christmas article: The beards of philosophers

Beards can tell you a lot about a man. Their style, their personality, even their financial status, all can be told by a man’s beard. Facial hair is often viewed negatively, particularly after the notorious ‘Hitler tasche’, and is seen as something that must be removed. However, in the time of the Ancient Greeks and Romans, a beard was seen as a common part of most men. They were often an indicator of social and political factors, the common man wore his beard short and well kempt, while kings and notorious fighters would have more elaborate facial hair. A beard also showed manliness, something very important in the patriarchal society of the time. It would separate them from the beardless women and children, elevating them in a sense.

It is not clear exactly how or why philosophers became synonymous with long, straggly beards but today it is one of the first things that come to the minds of non-philosophers when the subject is mentioned. Perhaps it is because they were so intensely preoccupied with setting the foundations of philosophy that they didn’t have the time or the will to shave. Or maybe it is because some of the early greats, such as Pythagoras and Socrates, established it as a style, copied by later philosophers who wanted to reach such high levels of esteem. In fact, shaving was not that common in the early periods of Greek civilisation, so most men had what is now deemed to be a philosopher’s beard. While they didn’t necessarily distinguish the philosophers from your average citizen, members of different schools of philosophy had their own styles of facial hair.

According to a Wikipedia contributor, the link between philosophers and beards began when three Greek philosophers arrived in Rome, all of whom were bearded, in 155 BCE. At this time, it had become common culture for Romans to shave their beards, so when these mysterious, bearded men arrived, they captivated locals. In fact, many Romans had decided to shave their beards so they were not mistaken for Greeks as this could potentially have led to racial persecution. When the Roman Emperor Domitian banned all philosophers from Rome, many shaved their beard to hide their profession or to avoid being mistake as one. In fact it led to many famous figures emigrating from Rome, simply because of a mad Emperor’s paranoia.

While beards are widely associated with intellect, there is certainly no correlation between the two. For every Plato or Aristotle, there are thousands of bearded men of average or below average intelligence. There is a common saying that goes ‘A long beard does not make you a philosopher’. In fact, a lot of poems and phrases mock suggestions of links between the two. Lucian wrote ‘If you think that to grow a beard is to acquire wisdom, a goat with a fine beard is at once a complete Plato’. Although there is no link between intelligence and beards, The modern day ‘Trustworthiness of beards’ scale puts the philosophers beard at number 2, being very trustworthy (see dig.).  In short, a philosopher beard will not make you smart, but you will become a trusted character.

Contributed by James Axton

Are Sea Ice levels really declining?

It is well known that global warming is affecting the poles dramatically. However, while sea ice extent at the North Pole has reached record lows, the coverage has been increasing in the South.

A recent study carried out by NASA and the British Antarctic Survey has been able to explain the sea ice drift in the Antarctic that has occurred over the last 20 years. They have found evidence to prove that changing winds have caused sea ice cover in the Antarctic to increase, despite the effects of climate change, which was published in ‘Nature Geoscience’. Maps created by the ‘Jet Propulsion Laboratory’ at NASA, which used more than five million daily ice motion measurements recorded for 19 years, have shown the changes in sea ice drift, which, until now, were unproven. Before this, the drift was merely hypothesised with the use of models of Antarctic winds but now this theory has a substantiated basis.

The growth of sea-ice cover is not spread evenly, with certain areas undergoing greater gains or losses. The diagram shows where growth is fastest, with the red areas in the northern and south-western parts of the continent experiencing the fastest rates. However, the blue regions in the north-west and north-east have been experiencing a decline, the area with the most rapid of shrinking is around the Antarctic Peninsula. This shows that the trends are not widespread and that the change of ice sheets is controlled by local changes in the winds. The winds affect the ice coverage by the air temperature as well as ice drift. Generally, the sea ice is blown away from the continent as a result of powerful northwards wind and since 1992, the spread of ice has doubled in areas but decreased hugely in others.

Globally, this sea ice spread is important because it reflects the sun’s heat as well as creating habitats for marine organisms. For obvious reasons, sea ice cover is thinner and less spread, but during the winter it grows and insulates the ocean from the freezing winter temperatures, allowing marine life to survive.

The growth of sea ice in the Antarctic is a stark contrast to the rapid decline of the Arctic, where the ice has reached record lows this summer. On September 16th 2012, seasonal melt meant the sea ice receded to 3.41 million square kilometres, the lowest seasonal minimum since satellite records began in in 1979. These surpass the previously smallest levels from 2007 by 760,000 square kilometres, 18% lower.

It is thought that this was caused by increasing levels of seasonal ice which forms over the winter, as it is thinner and gets broken up a lot easier than permanent ice. This causes a positive feedback loop to develop in which melt is quickened by increasing levels of seasonal ice, leading to more ice melt and so on. This year was also made worse by a large Arctic storm which caused this very thin ice to be completely destroyed.

While this melt is seasonal and the sea ice will refreeze at rates of up to 100,000 square kilometres a day, these levels of melt cannot be ignored. The levels of melt will probably grow in severity of the coming years due to global warming and it is expected that the Arctic will be ice free during the summer within 20 years.

It is important to point out that this does not disprove climate change, as the Antarctic Peninsula has shown the same warming as the rest of the Southern Hemisphere. While the sea ice expands, glacial ice is decreasing rapidly. As interesting as the expansion of sea ice is, it is important that these do not blur anybody’s views on climate change; the melt at the North Pole should be evidence enough.

Contributed by James Axton