Corroding pipe organs
storms as climate warms
1999, Armin Schoof, a professor of music and the organist at St. Jakobi Church
in Lübeck, Germany, discovered severe cracks and holes in the lead pipes
of the churchs famous Stellwagen organ. Fearing the loss of the 15th-century
instrument, Schoof contacted researchers at the Göteborg Organ Art Center
at Göteborg University, Sweden.
Lead and lead-alloy pipes in the Stellwagen organ at St. Jakobi Church in Lübeck,
Germany, are corroding away. The organ was built in 1467, and still contains
original pipes. Researchers are working to determine the cause of the decay.
Courtesy of Carl Johan Bergsten.
Carl Johan Bergsten, a research engineer at the Göteborg Organ Art Center,
gathered together a team of metallurgists, environmental chemists and organ
restorers, and they soon found that the problem was more widespread: Of the
10,000 historic instruments remaining in Europe dating from the 15th to 17th
centuries, the mysterious deterioration has already affected more than 1,000
and possibly more. During the last few decades, this deterioration has
accelerated. Unchecked, the corrosion of the metal pipes will change the sounds
of these historic artifacts, perhaps even silencing them.
Most organ-builders restoring or repairing historical organs find pipe corrosion.
Corrosion usually begins with cracks and holes in the foot of a metal pipe and
continues to move upward toward its mouth, eventually causing a complete collapse.
If the corrosion reaches the mouth, the sound properties will gradually
change and finally the pipe will be silent, Bergsten says. This
is serious because the historical sound quality will be lost and the sounding
cultural heritage is forever gone.
Bergsten says that it is too early to draw any final conclusions about the cause
of the corrosion. The project that he leads, called the Corrosion of Lead and
Lead-Tin Alloys of Organ Pipes in Europe project (known as COLLAPSE), is addressing
many factors inside churches, including changing temperature, humidity and condensation
and indoor pollutants, such as acidic vapors released by wood in the organ.
The researchers are also considering outdoor pollutants emitted from traffic,
agriculture and industry.
Team members are now analyzing samples from affected pipe organs in Italy, Belgium,
the Netherlands and Germany, and comparing them to samples from unaffected organs
in similar climatic regions. Preliminary findings show that alone, inorganic
pollutants, such as sulfur dioxide and nitrogen oxides, do not seem to be the
culprit. However, Bergsten says, a combination of the factors could be causing
the corrosion, something the team will test in field and laboratory analyses
of different pollutants interacting in varying environmental conditions.
Researchers do know that not all types of pipes are equally prone to corrosion.
Carla Martini, a metallurgist at the University of Bologna in Italy, says that
so far, most analyses have been of lead-rich pipes containing less than 4 percent
tin by weight. The extent to which [the pipes] are affected by corrosion
in a given environment changes with the composition of the alloy, namely with
the tin content, Martini says, with the most corrosion found in pipes
containing 1.5 to 2 percent tin.
In some cases, earlier attempts at conservation might now be causing corrosion.
While investigating the Stellwagen organ, researchers discovered the powdery
residues of lead compounds that are usually produced by interactions with organic
acids. Analysis of the air inside the organ found high concentrations of acetic
acid, which corrodes lead even in very low concentrations. Wood, especially
oak, is known to emit organic acids, Bergsten says, and the acetic acid
may be from oak that was used to repair the wooden windchests and wind system
of the organ in the 1970s.
Developing better conservation strategies is one of the main goals of the project,
which is supported by the European Union. By understanding the sources of corrosion,
it might be possible to change an organs environment to protect it. If
not, researchers are also developing protective treatments that could be applied
to the surface of a pipe. They expect to test experimental conservation strategies
on the Stellwagen organ by 2005.
Geotimes contributing writer
storms as climate warms
Last fall, four hurricanes cruised up Florida and the U.S. East Coast. Across
the globe, Japan was hit by 10 typhoons in its worst storm season in decades.
To the other extreme, recent droughts are ongoing in the Western United States
Aspects of this extreme weather may be related to global climate change, some
scientists say: As climate continues to warm, hurricanes and other storm events
may increase in intensity, and extreme storms increase in frequency. On the flip
side, droughts may become more frequent and severe.
Its always possible to have extreme weather events, says Kevin
Trenberth of the National Center for Atmospheric Research (NCAR) in Boulder, Colo.
A few large storms can always happen by chance, even in conjunction, he says.
However, with hurricanes, the odds are actually changing, Trenberth
says, and theyre changing in ways that match models of whats
happening in climate change.
Scientists have tracked an increase in rainfall over the past few decades. Data
over the past century in the United States shows that total precipitation increased
by 7 percent, and extremely large storms increased 14 percent, according to Pavel
Groisman and co-workers at the National Climatic Data Center in Asheville, N.C.
Publishing in the Journal of Hydrometeorology last February, the team noted
that most of the increase in precipitation days has happened within the past 30
Climate change impacts do not stop with rainfall, but affect droughts as well.
The steady buildup of carbon dioxide from human activity and other factors has
added a lot of energy to the climate system, Trenberth says. That energy causes
more drying, which pulls more water into the atmosphere in some spots, and then
leads to more precipitation in others. Where its not raining, it causes
more droughts, Trenberth says, and where it is raining, it gathers
together and causes flooding.
Ongoing drought in Australia corresponds to flooding in Peru, scientists say,
as does drought in Southeast Asia and parts of Africa, places that normally are
wetter during the La Niña part of the El Niño/Southern Oscillation
climate cycle. Moreover, Trenberth says, even though the 2002-2003 El Niño
was considered moderate, Australias drought is one of the most severe on
This years typhoon season in Japan is the worst since the country started
collecting complete records of its storms in 1970, according to Matthias Weber,
senior vice president of the U.S. Direct Americas division of Swiss Re, an international
reinsurance company. The company expects the season will last one month
longer than usual, Weber said in a telephone press conference in October.
Swiss Re estimates that the damage from the four hurricanes that hit Florida this
year will approach $20 to $25 billion, with more than twice as many claims as
Hurricane Andrew in 1992.
Some researchers, however, argue that the past climate record is not complete
enough to determine whether the shifts are just part of a natural cycle. Several
recent studies have compared the recent increase in hurricanes in the United States
mid-Atlantic region to past periods, particularly the 1920s to the 1960s, indicating
a possible cyclic pattern of 25 to 40 years.
With the current state of the science, says Tom Knutson of the National Oceanic
and Atmospheric Administration, we cant say much about global frequency
of hurricanes and typhoons with changing climate. On the other hand, writing
in the Sept. 15 Journal of Climate, Knutson and his co-workers have modeled
a gradual increase in hurricane intensity in a warmed climate, amounting to a
half-category increase in hurricane level a century from now.
We cant say anything about the changes in frequency of hurricanes,
says Trenberth, who also spoke at the October press conference, but we certainly
expect theres going to be more activity. The question, he says, is
whether there will be more individual thunderstorms, or whether thunderstorms
will come together more often to form hurricanes. Hurricanes require just the
right environmental conditions to coalesce, in winds that will not blow the storm
apart but will allow it to rotate.
What is clear is that there will be more disturbances there may be
more tropical storms rather than hurricanes, Trenberth says, and with those
storms, heavier rainfall and more damage.
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