Reconstructing Sea Levels in Venice, Italy from 1700 to

1872

Nick AngeliniLaura CorsettoDavid DeFuscoMichael Scarsella

In cooperation with CNRAdvisors: Dario Camuffo

Alberto GalloEmanuela Pagan

IntroductionIntroduction

Social Implications-Tide levels have been rising all over the world for centuries.-The melting of polar ice caps has caused much of this sea level rise9% area decrease per decade20% area decrease since 1979-Industrial revolution effects starting in 1860

*Is the rise in sea level natural, or has man influenced it?

Artic cap area decrease since 1979(NASA)

IntroductionIntroduction

-The rising rate of the sea level in Venice is unknown from 1700 to 1872.-Gap needs to be filled in order to fully analyze contributing factors behind rising sea levels. -Acqua Alta occurs 20 times per year on average.

St. Mark’s square, September, 2001

Mission StatementMission Statement

Using similar photographic analysis methods, accurate paintings will be examined to

determine what the sea levels were during the time period of each of the paintings. By applying data collected from paintings,

photos, and engravings in canal walls, this project will verify Camuffo’s results and

provide a more accurate reconstruction of sea levels in Venice from 1700 to 1872, when

automated tide gauges came online.

ApproachApproach

Understand background information

Create appropriate methodologyResults and analysisConclusion

BackgroundBackground

Selected artistsC markersPhotographs Dario Camuffo’s results

Venetian ArtistsVenetian Artists

Who? When?– Canaletto 1725-1755– Bellotto 1745-

1765– Guardi 1760-1780

Why rely on Venetian art?– Accuracy

Camera obscura Antonio Givanni "Canaletto" Canal (1697-1768)

Camera ObscuraCamera Obscura

Primitive lens system Extremely accurate

for its time How it works:

– Light through lens– Mirror reflects light

onto surface– Canvas placed on

surface– “Photographic” image

created

Camera ObscuraCamera Obscura

Primitive lens system Extremely accurate

for its time How it works:

– Light through lens– Mirror reflects light

onto surface– Canvas placed on

surface– “Photographic” image

created

Camera ObscuraCamera Obscura

Primitive lens system Extremely accurate

for its time How it works:

– Light through lens– Mirror reflects light

onto surface– Canvas placed on

surface– “Photographic” image

created

Venetian PaintingsVenetian Paintings

Canaletto’s “Disciples” Belloto and Guardi

Notice algae line– Average high tide

level – Comune MarinoLa Punta Della Dogana (1727)

C markersC markers

C markers – Documents

comune marino per year

– Etched in stone on canal walls

– Many locations unknown (WPI-IQP)

PhotographsPhotographs

Earliest known photos of Venice (mid-1800s)

Will be used in coalition with paintings

More accurate than paintings

Later timeframe for extended dataset

Project TechniquesProject Techniques

Reconstruct sea levels – Present-day replication of views

Paintings, Photographs

– Waterline differential (height) Photo measurements vs. on-site measurements

– Plot data of average sea level Vs. time (yrs) Data comparison to global warming statistics

– Apply information to or from C-Marker data

Learning from the Past…Learning from the Past…

Dario Camuffo (CNR)– Originator of sea-level

construction concept.– Learn from his work

(11 paintings used)– Improve upon his work

Two additional approaches

– Photographs– C markers

Dario Camuffo of CNR

……Applying toward the FutureApplying toward the Future

Selection of Venetian landscape portraits– Database created

Utilized Catalogue Raisonné

– Catagorized appropriately for future use Date, Image, Source, other info.

– Narrowed down by visible Comune Marino line

Digital ReproductionsDigital Reproductions

Map locations of paintings

Obtain copies of photographs – Map locations

Go to locations– Take digital photos of

present-day views– Measure to fixed points

near and far, in 3 dimensions.

– Document DataMap of sea levels and painting locations

Waterline DifferentialWaterline Differential

Record on-site measurement dataMeasure same distances within

photo/portrait.– Create a ratio (scale)

Distance from comune marino in comparison to today.

Derive Quantitative data – Water level in year of each

photo/portrait.

Waterline Differential Cont.Waterline Differential Cont.

• Side-by-side comparison of photos

• Obvious comune marino shift

Photo Courtesy of Dario Camuffo, 2002

• Example shows a 44 cm +/- 10 shift since 1880

• Side-by-Side gives visual confirmation of numeric data

C-MarkersC-Markers

Dated C-Markers checked for support to tide progression trend

If not dated – possible to date with tide information. – Height corresponds to year on tide progression

chart. Markers photographed and documented

for database. Treated as a tertiary source for data if

deemed reliable.

Results and AnalysisResults and Analysis

Create graphical representations of data– Graphs, charts, tables, database

Comparison of data– Global warming

Look for human influences

– Pre-recorded tide data since 1872 Look for correlation

Graphical RepresentationGraphical Representation

• Gather relevant data

• Height differential

• Year of photo/portrait

• Plot data points

• Tide progression

Data ComparisonData Comparison

• Compare tide progression line with global warming data

Comparison to Tidal DataComparison to Tidal Data

KEY: Left to Right

•Canaletto & Bellotto

•Photographs

•Tide Gauge data (Blue)

measured sea level since 1872

Courtesy of Dario Camuffo

ConclusionConclusion

Ultimately aid researchers– Known tidal levels

Two Centuries prior to what is currently known

– Comparable to global warming data

Discover human influence on sea level rise

– Find a cause for sea level rise since 1700

Thank You!