Friday, April 28, 2017

Global Warming Vs. Venice Italy

Global Warming Vs. Venice Italy --- ===

Isn't the flooding in Venice caused by global  warming?  What you haven't been told is that anybody can look up on Wikipedia that people in Venice have been complaining about flooding since  the year 589.

wikipedia: global warming has been linked to increased eustasy. Venice's "Tide Monitoring and Forecast Center" evaluates that the city has lost 23 cm. in its elevation since 1897,  the year of reference, 12 of which are attributable to natural causes (9 because of eustasy, 3 because of subsidence), 13 are due to the additional subsidence caused by human activity, while the "elastic recovery" of the soil has allowed the city to "gain back" 2 cm.

Venice subsided about 120 mm in the 20th century due to natural processes and groundwater extraction, in addition to a sea level rise of about 110 mm at the same time, Teatini said in a statement. Bock and his colleagues calculate that the city and surrounding land could sink by about 80 mm (3.2 inches) relative to the sea in the next 20 years if the current rate holds steady.

Sea-level rise isn't the only thing that has Venice's famous canals rising ever-so-slightly every year: The city is also sinking, a new study shows, in contrast to previous studies that suggested the city's subsidence had stabilized.

Did Bill Nye say that flooding in Venice caused by global  warming?  He didn't say that people have been complaining about flooding since  the year 589.

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Apr 21, 2017 - Aptly titled "Bill Nye Saves the World," the long-awaited reboot was ... and computer programming enthusiast who goes to Venice to look at the ...Karlie Kloss, the supermodel and computer programming enthusiast who goes to Venice to look at the rising waterways in the first episode.

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Precise scientific parameters define the phenomenon called acqua alta,[1] the most significant of which (i.e., the deviation in amplitude from a base measurement of "standard" tides) is measured by the hydrographic station located nearby the Basilica di Santa Maria della Salute. Supernormal tidal events can be categorized as:
  • intense when the measured sea level is between 80 cm. and 109 cm. above the standard sea level (which was defined by averaging the measurements of sea level during the year 1897);
  • very intense when the measured sea level is between 110 cm. and 139 cm. above the standard;
  • exceptional high waters when the measured sea level reaches or exceeds 140 cm. above the standard.
Generally speaking, tide levels largely depend on three contributing factors:
  • An astronomical component, which results from the movement and alignment of celestial bodies, principally the Moon, secondarily the Sun, and marginally other planets (with effects decreasing in logarithmic relation to their distance from the Earth); this component is dependent upon the laws of the astronomical mechanics and can be computed and accurately predicted for the long run (even years or decades)
  • A geophysical component, primarily dependent upon the geometric shape of the basin, which amplifies or reduces the astronomical component and, because it is dependent upon the laws of the physical mechanics, can be also computed and accurately predicted for the long run (even years or decades);[2]
  • A meteorological component, linked to a large set of variables, such as the direction and strength of winds, the location of barometric pressure fields and their gradients, precipitation, etc. Because of their complex interrelations and quasi-stochastic behavior, these variables cannot be accurately modeled in statistical terms. Consequently, this component can only be forecast for the very short run and is the principal determinant of acqua alta emergencies that catch Venetians unprepared.[3]

Satellite image of the Adriatic Sea, highlighting the long and narrow rectangular shape which is the source of an oscillating water motion (called seiche) along the minor axis. The oscillation, which has a period of 21 hours and 30 minutes and an amplitude around 0.5 meters at the axis' extremities, supplements the natural tidal cycle, so that the Adriatic sea experiences much more extreme tidal events than the rest of the Mediterranean.
Two further contributing natural factors are the subsidence, i.e. the natural sinking of the soil level, to which the lagoon is subject, and eustasy, i.e. the progressive rise of sea levels. While these phenomena would occur independently of human activity, their effects have increased because of inhabitation: the use of lagoonal water by the industries in Porto Marghera (now ceased) speeded up subsidence, while global warming has been linked to increased eustasy. Venice's "Tide Monitoring and Forecast Center" evaluates that the city has lost 23 cm. in its elevation since 1897,[1] the year of reference, 12 of which are attributable to natural causes (9 because of eustasy, 3 because of subsidence), 13 are due to the additional subsidence caused by human activity, while the "elastic recovery" of the soil has allowed the city to "gain back" 2 cm.

Historical records[edit]

Venice: tourists on the gangways queuing to enter the San Marco basilica.

Early records[edit]

The first record of a large flood in the Venetian lagoon dates back to the so-called Rotta della Cucca, reported by Paul the Deacon[12] as having occurred on October 17, 589. According to Paul, all rivers with mouths in the northern Adriatic, from the Tagliamento to the Po, overflowed at the same time, completely modifying the hydro-geologic equilibrium of the lagoon.

Middle Ages[edit]

The first documented description[13] of acqua alta in Venice concerns the year 782 and is followed by other documented events in 840, 885, and 1102.
In 1110 the water, following a violent sea storm (or, possibly, a seaquake and its subsequent tsunami), completely destroyed Metamauco (ancient name for Malamocco), Venice's political centre before the Doge's residence was moved to Rialto.
Local chroniclers report that in 1240 "the water (that) flooded the streets (was) higher than a man".[13] Other events are recorded to have occurred in 1268, 1280, 1282, and on December 20, 1283, which was probably an abnormally significant event, since a chronicle reported that Venice was "saved by a miracle".[13]
Chroniclers report that high tides occurred in 1286, 1297, and 1314; on February 15, 1340; on February 25, 1341; on January 18, 1386; and on May 31 and August 10, 1410.
In the 15th century, high tides were recorded in 1419 and 1423, on May 11, 1428 and on October 10, 1430, as well as in 1444 and 1445. On November 10, 1442 the water is reported to have risen "four feet above the usual".[13]

Modern Era[edit]

High waters were recorded on May 29, 1511; in 1517; on October 16, 1521; on October 3 and, again, on December 20, 1535. Local chronicles also attest to floods occurring in 1543; on November 21, 1550; on October 12, 1559; and in 1599.
The year 1600 was characterized by a high frequency of events, with floods on December 8 as well as December 18 and 19. The latter event was probably remarkable, since there are also records of very violent sea storms that, having "broken indeed the shores in several places, entered the towns of Lido Maggiore, Tre Porti, Malamocco, Chiozza, et cetera".[13]
Another noteworthy acqua alta took place on November 5, 1686. Several chronicles of the time, among them one written by a scientist, concur in reporting that "the waters reached the outdoor floor of ... [Sansovino's] Lodge", which is the monumental entrance to the Campanile di San Marco. A similar level was reached during the exceptional flood of November 4, 1966, which allowed scholars in the late 1960s to recreate a likely scenario for the 1686 flood. After accounting for the rebuilding of the Lodge after the 1902 fall of the Campanile and for subsidence, estimates concluded that the tide may have been as high as 254 cm. above today's standard sea level.[14]
In the 18th century, records became more abundant and precise, reporting acque alte on December 21, 1727; New Year's Eve, 1738; October 7, 1729; November 5 and 28, 1742; October 31, 1746; November 4, 1748; October 31, 1749; October 9, 1750; Christmas Eve, 1792; and on Christmas Day, 1794.
Finally, in the decades before the installation of the marigraphs, high waters are recorded to have occurred on December 5, 1839, as well as in 1848 (140 cm) and 1867 (153 cm).

Exceptional high waters since 1923[edit]

The levels reached by high waters, engraved on the walls of Ca' Farsetti, Venice's City Hall.

The levels reached by waters, painted outside a Venice shop
According to the records of the Tide Monitoring and Forecast Centre of Venice,[1] these are the maximal documented levels (in decreasing, not chronological, order):
  • 194 cm on November 4, 1966
  • 166 cm on December 22, 1979
  • 158 cm on February 1, 1986
  • 156 cm on December 1, 2008
  • 151 cm on November 12, 1951
  • 149 cm on November 11, 2012
  • 147 cm on April 16, 1936
  • 147 cm on November 16, 2002
  • 145 cm on December 25, 2009
  • 145 cm on October 15, 1960
  • 144 cm on December 23, 2009
  • 144 cm on November 3, 1968
  • 144 cm on November 6, 2000
  • 143 cm on February 12, 2013
  • 143 cm on November 1, 2012
  • 142 cm on December 8, 1992
  • 140 cm on February 17, 1979
  • Maximum high tide level: 1.94 m recorded on November 4, 1966
  • Minimum ebb tide level: -1.21 m, recorded on February 14, 1934
  • Maximum difference between a high tide and the following ebb tide: 1.63 m, recorded on January 28, 1948 and on December 28, 1970
  • Maximum difference between an ebb tide and the following high tide: 1.46 m, recorded on February 23 and 24, 1928, as well as on January 25, 1966