Book Readings: Week 7

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.

I don't have much left to read in Carson's The Sea Around Us, as it is a considerably shorter book than The Tide, so I am only blogging about small portions of the book from here on out since my intent is to read and blog about both books concurrently. Last week, I finished the middle portion of Carson's book, titled "The Restless Sea." This week, I begin "Man and the Sea Around Him." In this final section of book, Carson focuses on the relationship between humans and the seas, and how we are affecting the global ocean (most often for the worse, and not better).

I was shocked to learn that back in the 1950s when Carson was writing her book, people were actually talking about trying to control, influence, and even modify through human engineering the paths of major ocean currents, like the Oyashio in the Pacific and the Gulf Stream in the Atlantic. The idea behind modifying the Gulf Stream was to bring its waters closer to the mainland of the northern United States in the hopes of producing warmer weather. It blows my mind that anyone would seriously entertain playing with such major global processes just to enjoy nicer weather, and I'm glad such ideas aren't as easily entertained these days when it comes to ocean currents.

When I read Carson's descriptions of how the ocean can regulate regional climates, I wasn't surprised by the concept that the ocean often has a moderating effect on climate, ensuring that coastal environments are never too extreme in weather. It's a process that I've read about many times. However, the concept of "marine deserts" being created by the ocean was new to me. Such deserts occur in places like the coasts of Chile and Peru, where cold, moist air situated over cold, upwelled water moves inland. Although this cool air carries moisture, it heats up as it travels inland and rises instead of falling. Because of this, the moisture in it cannot be captured as rain so rainfall in the region is very limited, creating desert conditions. Only an El Niño event, which brings warmer, moist air that sinks as it moves inland can bring major amounts of rainfall, often with disastrous consequences.

Finally, what I found particularly interesting this week was Carson's description of the "Pettersson tidal theory," a theory which states that there is a tidal cycle which lasts 1,800 years. This cycle could explain why centuries rife with extreme weather events and cooler climates seem to be followed by centuries of less and less extreme weather events, culminating in centuries of warmer, milder weather which then swings back to cooler, more extreme weather to complete the cycle. Carson describes how Greenland in the year 984 CE was described as a temperate, mild, even fruit-laden land, and year only a few centuries later in the 1300s became significantly covered in ice and snow. She points out that these swings in climate were mirrored all across Europe, and that since that cold period we have been experiencing warmer and warmer weather, though we are still about four centuries away from the warmest and mildest weather in the cycle.

Part of what I found interesting about this discussion of the Pettersson cycle was that there was absolutely no mention of the anthropogenic factors affecting climate. Carson was writing in the 1950s when the understanding of humanity's role in global warming was minimal at best, and granted, in 1950 the Earth did not have the elevated levels of greenhouse gases in the atmosphere as it does now. Nevertheless, it was strange to read about a 1,800-year cycle of cooling and warming in the Earth's climate that made no mention of the role of humans.

In The Tide this week, Aldersey-Williams starts off by talking about the River Elbe in Hamburg, Germany. Hamburg is home to Germany's largest port, and Aldersey-Williams says that alterations made to the river over time to make it easier for larger and larger transport vessels to navigate the water have also made it easier for the effects of high tide to reach further upriver.

Unfortunately, these alterations also made the areas near the river more vulnerable to flood event, and hundreds of people died along the river during an extreme flood event as recently as 50 years ago, even far inland. It's a sobering reminder of how the alterations or "engineering" we do to our environment for our convenience can be detrimental to us in the long-term, and how ultimately we cannot beat the forces of nature. Indeed, Aldersey-Williams says that because of the soft-sediment nature of the Elbe, the banks and course of the river are constanty shifting, requiring constant dredging and maintenance to maintain the convenient shipping channel that is desired.

I was entertained to read about how the Boston Tea Party, a key event in early US history, was influenced by the tides. Aldersey-Williams writes that when the tea was being thrown overboard at night, the tide was actually very low, and so the chests filled with tea that were thrown overboard weren't traveling out to sea but instead gathering in piles in the harbor in the exact places where they were tossed. Men were even ordered to into the waters to break up the chests and swish the loose tea further out to sea using paddles. Because the event happened at low tide, the chests didn't have an opportunity to really disperse far and wide and many of them actually washed back up on shore nearby, from where they were surreptitiously taken by residents who took the tea home for personal use.

Another of Aldersey-Williams' stories I enjoyed was that of the Japanese empress Jingu, who ruled around the year 200 CE and conquered Korea around that time. According to myth, Jingu used jewels given to her by Shinto gods to control the tides to successfully battle Korean warships and decimate the opposing soldiers. While the story of jewels are clearly a myth, it's interesting to see how this and other war stories from history that Aldersey-Williams recounted in earlier chapters (such as with Viking invasions of the British isles) are rooted in the factual context of one party having a greater knowledge of the tides than the other.

Aldersey-Williams then turns his attention to tidal bores, which is essentially a large wave caused by the channeling of an incoming flood tide as it enters a long, narrow, and shallow waterway. In order to talk about tidal bores, Aldersey-Williams travels to the Shubenacadie River, which eventually empties into the Bay of Fundy in Nova Scotia. This bay famously features the largest tidal range in the world, and the tidal bore surges up the Shubenacadie after it enters the bay.

I really enjoyed Aldersey-Williams' descriptions of the scenery as he watched a tidal bore surge up the Shubenacadie. He talks about how the bore is so intense that you can see a difference of at least a foot in the height of the water on either side of a footbridge that crosses the river. The color of the water also changes as the bore surges in, changing from a darker, clearer tone to one that is more opaque and pale brown as the bore lifts sediments off the riverbed and increases the turbidity of the water. In past weeks I talked a lot about how Rachel Carson paints vivid images with her words, and I can say the same for Aldersey-Williams here.

Finally, I was interested but also concerned after learning that the Bay of Fundy is a prime location, due to the massive strength of the tides, for testing out whether or not the energy of the waves and tides can be harnessed for human use. I was relieved to read that such testing is only in its earliest stages, and I appreciated that Aldersey-Williams himself raised concerns about the idea. Besides the fact that underwater turbines to harness tide power would likely adversely affect the bay's sturgeon population and 60 other species of fish, the author points out that while there may be a lot of energy bound up in tidal forces, it is a fraction compared to what is theoretically available to us in other renewable sources, particularly solar and geothermal. I really hope that these attempts to "engineer the ocean" don't make it past the exploratory stage, as I think it could end up being a costly waste of time, not just financially but from an environmental perspective as well.

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.