Posts Tagged ‘Earth Changes’

The Watchers Tweet Tweet Arctic has been experiencing a shift in the general patterns of high and low pressures recently, as well as the direction and speed of the winds. These changes may explain some of the dramatic sea ice loss experienced in the Arctic regions. Wind speed and direction are driven by differences in atmospheric pressure. Generally, air moves from areas of high to low pressure – the greater the pressure difference between two areas, the faster...

    Arctic has been experiencing a shift in the general patterns of high and low pressures recently, as well as the direction and speed of the winds. These changes may explain some of the dramatic sea ice loss experienced in the Arctic regions. Wind speed and direction are driven by differences in atmospheric pressure. Generally, air moves from areas of high to low pressure – the greater the pressure difference between two areas, the faster the air moves.

    According to a new NOAA-led study published on October 10,2012 in Geophysical Research Letters, changes in summer Arctic wind patterns contribute not only to an unprecedented loss of Arctic sea ice, but could also bring  shifts in North American and European weather. As Arctic warms at twice the global rate, scientists expect more extreme weather events like heatwaves, floodings or heavy snowfall across the temperate latitudes of the northern hemisphere, where billions of people live.

    Comparison of the atmospheric pressure (geopotential height at 700 mb) experienced during June of 2007-2012 compared to the longer term average for June from 1980-2010. Much higher pressure is found directly over the Arctic Ocean and Greenland. This difference in pressure has resulted in a change in the wind patterns. Orange arrows indicate the relative direction and strength (indicated by the arrow length) or winds during the 2007-2012 periods, whereas the white arrows are the 1980-2010 average. The most pronounced changes in winds can be seen over the Chuchki Sea, just northeast of Alaska and also east of Greenland. (NCEP Reanalysis data provided by NOAA/ESRL/PSD)

    A research team led by a NOAA research oceanographer James Overland, Ph.D., of NOAA’s Pacific Marine Environmental Laboratory in Seattle, Washington, uncovered a change in the summer Arctic wind pattern over the past six years. They point that this shift demonstrates a physical connection between reduced Arctic sea ice in the summer, loss of Greenland ice, and potentially, weather in North American and Europe.

    The team examined the wind patterns in the subarctic in the early summer between 2007 and 2012 as compared to the average for 1981 to 2010. The new study show that the previously normal west-to-east flowing upper-level winds have been replaced by a north-south undulating wave-like pattern. This new wind pattern transports warmer air into the Arctic and pushes Arctic air farther south. This may influence persistent weather conditions in the mid-latitudes. Higher pressure over the North American continent and Greenland is driving these changes in the early summer wind patterns.

    Warmer air and sea temperatures caused by global warming are rapidly changing Arctic environment but this new shift provides additional evidence that changes in the Arctic are also part of an “Arctic amplification” through which multiple specific physical processes interact to accelerate temperature change, ice variability, and ecological impacts. The effects of Arctic amplification will increase as more summer ice retreats over coming decades. Enhanced warming of the Arctic affects the jet stream by slowing its west-to-east winds and by promoting larger north-south meanders in the flow.

    Sea ice in the Chukchi Sea, on July 20, 2011. Sea ice in the Arctic has shrunk to the lowest levels ever recorded (Credit: Jeremy Potter NOAA/OAR/OER)

    Since 2007, the summer winds were found to blow through the Bering Strait, across the North Pole, more consistently from the south, out toward the Atlantic Ocean. These winds transfer additional heat from the south toward the North Pole and push sea ice across the Arctic and out into the Atlantic Ocean, contributing to record losses of summer sea ice. The 2012 Arctic summer sea ice minimum is the lowest on record.

    The study, entitled “The Recent Shift in Early Summer Arctic Atmospheric Circulation,” was co-authored by scientists from Rutgers University in New Jersey,  the University of Sheffield in the United Kingdom, and the Joint Institute for the Study of the Atmosphere and Ocean, a partnership of NOAA and the University of Washington. It can be found online.

    Sources: NOAA ClimateWatch, NNVL

    Featured image credit: (NASA/Kathryn Hansen)

    By chillymanjaro – October 24, 2012

    The Watchers Tweet Tweet 41,000 years ago, a complete and rapid reversal of the geomagnetic field occurred. As a consequence, the Earth nearly completely lost its protection shield against hard cosmic rays, leading to a significantly increased radiation exposure, a new study led by Dr. Norbert Nowaczyk and Prof. Helge Arz claims. A geomagnetic reversal is a change in the Earth’s magnetic field such that the positions of magnetic north and magnetic south are interchanged. The Earth’s field has alternated between periods...

      41,000 years ago, a complete and rapid reversal of the geomagnetic field occurred. As a consequence, the Earth nearly completely lost its protection shield against hard cosmic rays, leading to a significantly increased radiation exposure, a new study led by Dr. Norbert Nowaczyk and Prof. Helge Arz claims.

      A geomagnetic reversal is a change in the Earth’s magnetic field such that the positions of magnetic north and magnetic south are interchanged. The Earth’s field has alternated between periods of normal polarity, in which the direction of the field was the same as the present direction, and reverse polarity, in which the field was the opposite. These periods are called chrons.

      Magnetic studies of the GFZ German Research Centre for Geosciences on sediment cores from the Black Sea show that during this period, during the last ice age, a compass at the Black Sea would have pointed to the south instead of north.

      Moreover, data obtained by the research team formed around GFZ researchers Dr. Norbert Nowaczyk and Prof. Helge Arz, together with additional data from other studies in the North Atlantic, the South Pacific and Hawaii, prove that this polarity reversal was a global event. Their results are published in the latest issue of the scientific journal “Earth and Planetary Science Letters”.

      What is remarkable is the speed of the reversal: “The field geometry of reversed polarity, with field lines pointing into the opposite direction when compared to today’s configuration, lasted for only about 440 years, and it was associated with a field strength that was only one quarter of today’s field,” explains Norbert Nowaczyk. “The actual polarity changes lasted only 250 years. In terms of geological time scales, that is very fast.” During this period, the field was even weaker, with only 5% of today’s field strength. As a consequence, the Earth nearly completely lost its protection shield against hard cosmic rays, leading to a significantly increased radiation exposure.

      Abrupt climate changes and a super volcano

      Besides giving evidence for a geomagnetic field reversal 41,000 years ago, the geoscientists from Potsdam discovered numerous abrupt climate changes during the last ice age in the analysed cores from the Black Sea, as it was already known from the Greenland ice cores. This ultimately allowed a high precision synchronisation of the two data records from the Black Sea and Greenland. The largest volcanic eruption on the Northern hemisphere in the past 100 000 years, namely the eruption of the super volcano 39400 years ago in the area of today’s Phlegraean Fields near Naples, Italy, is also documented within the studied sediments from the Black Sea. The ashes of this eruption, during which about 350 cubic kilometers of rock and lava were ejected, were distributed over the entire eastern Mediterranean and up to central Russia.

      These three extreme scenarios, a short and fast reversal of the Earth’s magnetic field, short-term climate variability of the last ice age and the volcanic eruption in Italy, have been investigated for the first time in a single geological archive and placed in precise chronological order.

      (Helmholtz Centre Potsdam – GFZ German Research Centre for Geosciences. “Ice age polarity reversal was global event: Extremely brief reversal of geomagnetic field, climate variability, and super volcano.” ScienceDaily, 16 Oct. 2012. Web. 19 Oct. 2012.)

      NASA claims geomagnetic reversals are the rule, not the exception

      Above: Supercomputer models of Earth’s magnetic field. On the left is a normal dipolar magnetic field, typical of the long years between polarity reversals. On the right is the sort of complicated magnetic field Earth has during the upheaval of a reversal.

      In November 2011, NASA published an interesting article claiming this kind of geomagnetic reversals occur as a rule, not an exception. The N-S markings of a compass would be 180 degrees wrong if the polarity of today’s magnetic field were reversed. Many doomsday theorists have tried to take this natural geological occurrence and suggest it could lead to Earth’s destruction. But would there be any dramatic effects? The answer, from the geologic and fossil records we have from hundreds of past magnetic polarity reversals, seems to be ‘no.’

      The following is a part of above mentioned article with its headline as they wrote it:

      2012: Magnetic pole reversal happens all the (geologic) time

      Earth’s polarity is not a constant. Unlike a classic bar magnet, or the decorative magnets on your refrigerator, the matter governing Earth’s magnetic field moves around. Geophysicists are pretty sure that the reason Earth has a magnetic field is because its solid iron core is surrounded by a fluid ocean of hot, liquid metal. This process can also be modeled with supercomputers. Ours is, without hyperbole, a dynamic planet. The flow of liquid iron in Earth’s core creates electric currents, which in turn create the magnetic field. So while parts of Earth’s outer core are too deep for scientists to measure directly, we can infer movement in the core by observing changes in the magnetic field. The magnetic north pole has been creeping northward – by more than 600 miles (1,100 km) – since the early 19th century, when explorers first located it precisely. It is moving faster now, actually, as scientists estimate the pole is migrating northward about 40 miles per year, as opposed to about 10 miles per year in the early 20th century.

      Another doomsday hypothesis about a geomagnetic flip plays up fears about incoming solar activity. This suggestion mistakenly assumes that a pole reversal would momentarily leave Earth without the magnetic field that protects us from solar flares and coronal mass ejections from the sun. But, while Earth’s magnetic field can indeed weaken and strengthen over time, there is no indication that it has ever disappeared completely. A weaker field would certainly lead to a small increase in solar radiation on Earth – as well as a beautiful display of aurora at lower latitudes — but nothing deadly. Moreover, even with a weakened magnetic field, Earth’s thick atmosphere also offers protection against the sun’s incoming particles.

      The science shows that magnetic pole reversal is – in terms of geologic time scales – a common occurrence that happens gradually over millennia. While the conditions that cause polarity reversals are not entirely predictable – the north pole’s movement could subtly change direction, for instance – there is nothing in the millions of years of geologic record to suggest that any of the 2012 doomsday scenarios connected to a pole reversal should be taken seriously. A reversal might, however, be good business for magnetic compass manufacturers.

      Sources: Helmholtz Centre Potsdam – GFZ German Research Centre for Geosciences, sciencedaily.com, nasa.gov

      About the Helmholtz Centre Potsdam: The Helmholtz Association is dedicated to pursuing the long-term research goals of state and society, and to maintaining and improving the livelihoods of the population. In order to do this, the Helmholtz Association carries out top-level research to identify and explore the major challenges facing society, science and the economy. Its work is divided into six strategic research fields: Energy; Earth and Environment; Health; Key Technologies; Structure of Matter; and Aeronautics, Space and Transport. The Helmholtz Association brings together 18 scientific-technical and biological-medical research centres. With some 32,698 employees and an annual budget of approximately €3.4 billion, the Helmholtz Association is Germany’s largest scientific organisation. Its work follows in the tradition of the great natural scientist Hermann von Helmholtz (1821-1894).

      Featured image: Schematic illustration of Earth’s magnetic field. Credit/Copyright: Peter Reid, The University of Edinburgh

      By Adonai/The Watchers