Book Readings: Week 5

For my Marine Resources class (GEOG 646) at SF State this semester I am reading The Sea Around Us, by Rachel Carson (1951), and The Tide: The Science and Stories Behind the Greatest Force on Earth, by Hugh Aldersey-Williams (2016). Please check out my first Book Reading blog post to read about why I chose these two books and why I chose to blog about them concurrently.

Last week, I had finished the first half The Sea Around Us, which was subtitled "Mother Sea." This section of the book serves as Carson's overview of all the different aspects of the oceans she felt it was important for us to know to get a complete picture of the sea.

This week, I began the next portion of the book, titled "The Restless Sea." In this section, Carson drills down into the subject of the movement of the ocean waters, from waves, to currents, and to tides. She begins by discussing waves, primarily surface waves, and discusses at length what (at the time) was cutting edge technology being used to record wave height and strength. In fact, this section of Carson's book seems to be a bit drier than "Mother Sea" as it focuses quite a bit on the actual instrumentation and methods used to study the oceans, but it was still interesting to read about what sort of technology was available for oceanographers in the 1950s to study the ocean (she also discusses technology used by seismologists, because earthquakes can cause tsunami events). At times it was also was surprising to me how technologically advanced ocean research already was at the time, even if by current standards it was somewhat rudimentary.

Carson's descriptions of the power of the waves are a bit more picturesque. She talks about the devastation that tsunami events can cause, and how constant wave action is the primary driver of coastal erosion. Her description of how waves can travel from one end of an ocean to the other drove home for me the way in which far off countries and peoples are all ultimately connected by the ocean. (In particular, Carson's description of how a massive earthquake in the Aleutian island chain caused a tsunami event in Hawaii in 1946 was one that really stuck with me.)

Carson then moves on to how the wind, the sun, and the earth's rotation all affect the movement of water. I was surprised to read that European sailors from as early as the first half 16th century already knew of the Gulf Stream, and used it to help their ships return home after forays into the Atlantic. I loved reading about how sailors could see the difference in color and character between the Gulf Stream waters (deep, dark blue, clearer) and the waters of the North Atlantic (lighter green, murky) as they sailed, and how the higher temperature of the Gulf Stream waters often caused massive banks of fog to form as the current traveled north into colder latitudes.

Carson talks about how masses of water can be stratified by temperature and salinity (which ultimately affect the density of the water) and how changes as one travels through one mass of water to another with a different temperature and salinity profile can be quite abrupt. She provides an excerpt of an account written by a sailor in 1944 about how, as his ship crossed from open water into the upwelling zone off the coast of Colombia, the surface waters suddenly changed from being relatively barren to suddenly teeming with life.

Before moving on to talk about the tide, Carson points out that deep ocean currents serve as a global circulation system, connecting the waters of all the world's oceans together. It was a nice reminder of how the planet functions as a single unified system.

It was at this point that I switched focused to Aldersey-Williams' book. In The Tide this week, the author talks about the city of Venice, which is well-known for its vulnerability to floods and rising sea levels. Many parts of the city are flooded on a daily basis.

Aldersey-Williams talks about how Galileo, the great scientist, actually spent a summer in Venice, at the northern end of the Adriatic Sea. I was surprised to learn that it was Galileo's observations of the tides in the Adriatic, along with observations of barges that brought fresh water to Venice for the citizens to drink, that inspired him to advocate for the idea of a Copernican, or heliocentric model of the solar system. By observing how the fresh water in the barges sloshed around in their open containers and how that mirrored the tidal action in the Adriatic Sea, Galileo deduced that the earth must rotate around the sun, and not the other way around. He also claimed that the earth's rotation around its own axis as well as around the sun was the sole cause of the tides.

Strangely, Galileo left out the moon's influence on the tide, and Aldersey-Williams says that perhaps this was because Galileo was so invested in advancing the Copernican theory that he ignored any evidence that might seem to contradict his model. For example, under Galileo's model there was only one high tide per day, whereas in most of the world one saw two high tides in a day. Aldersey-Williams makes a convincing case that Galileo, despite his great scientific achievements, was still limited by his own biases and by his local environment: The Adriatic Sea, which is what Galileo observed, is part of the Mediterranean, where there is a very small tidal range. In the Adriatic, these small lunar tides are essentially masked by the much larger influence of local factors on tidal oscillation such as strong winds and atmospheric pressure changes. In essence, Galileo's failing was in failing to understand that his observations of the Adriatic were not and could not be applicable to all the oceans of the world.

Aldersey-Williams then talks about how intentional flooding through the opening of dikes have been used in a strategic manner in the Netherlands to thwart invaders, even though it meant the destruction of valuable farmland. The threat of strategic flooding kept Kaiser Wilhelm II from invading the country during World War I, and during the Second World War, both sides of the conflict used strategic flooding to cut off or otherwise hamper the opposing forces. In fact, some research shows that a full third of all floods in the Netherlands since the year 1500 have been deliberate, defensive actions.

Then author also talks about about a destructive flood event on the east coast of England in 1953, and another one in Venice in 1966. In both cases, Aldersey-Williams points out that it was not the height of the floods at high tide that was the real problem as it was the fact that the high tide lasted for an incredibly large amount of time, causing sustained damage over the course of hours. Further damage would occur when the unusually high tide would recede as great speed, leaving damage in its wake.

After the 1953 flood, the Thames Barrier was constructed. Aldersey-Williams toured the Barrier in 2014, and learned that although London is now much more prepared for a major flood event than it would have been in 1953, it is actually now much more vulnerable due to the fact that so much development has taken place on land close to the water. Besides being so much closer to the water line, these buildings are situated over former salt marsh habitats which used to serve as a buffer zone for wave energy and as a sort of sponge that could absorb some of the incoming floods. With these marshes lost to development, the water now has nowhere to flow, except further upstream, which increases the destructive power of the floods. This section of the book really stood out to me because as a native of Redwood City and San Mateo County, development on the bayshore, particularly development that replaces valuable wetland habitats, has been a subject I have had to think about my entire life. Out of the nine counties of the San Francisco Bay Area, San Mateo County is the one with the most buildings and communities in the path of flooding and sea level rise, and yet most local governments in the county continue to push for development on the bayshore. It is a worrying state of affairs.

Aldersey-Williams ends by talking about a recent trip he made to Venice, where he learns about some of the new measures taken in the city to mitigate flood events and protect the city. I appreciated learning about how the city now views flood protection and ecological protection of the Venetian lagoon as one and the same, as apparently they did not before. It was inspiring to hear that every effort was being made to ensure that any flood protections put in place would do minimal damage to the local ecosystem, and as someone who works in a wetland restoration lab, I appreciated reading that natural restoration of barrier islands was being explored as a way to help mitigate the strength of flood events.

I also loved the Venetian concept of flood protection design, and how instead of building massive seawalls that would block the view of the water they designed underwater barriers that would only be raised during flood event. Even the buildings that house the controls for the barriers are designed so that they don't rise above the land, ensuring that the protection is as beautiful and unobtrusive as it is hopefully effective.

I'll be blogging again about both books at the same time next week. Stay tuned!

References:

• Aldersey-Williams, H. (2016). The tide: The science and stories behind the greatest force on Earth. New York, NY: W. W. Norton & Company, Inc.
• Carson, R. L. (1951). The sea around us (1989 ed.). New York, NY: Oxford University Press, Inc.