Sunday, November 4, 2012

The Sea Around Us - Rachel Carson

The namesake river of this blog – the Fraser River – is the largest watershed in the province of British Columbia, eventually emptying into the Strait of Georgia 1375km from its headwaters. From there, the river water becomes part of the vastness of the oceans. So few of us have traveled beyond a few kilometres from the shore; even fewer have crossed the ocean by ship. Often our only view of the centre of an ocean is from an airplane. As such, oceans remain places of mystery, inspiring stories of monstrous creatures living in the cold dark deep while challenging scientists to find ways to study their depths.

Rachel Carson was enamored of the mystery of the oceans. “The Sea Around Us”, published in 1951, is the second in what is known as her sea trilogy. It is a collection of 14 chapters, some of which were published as standalone articles in prominent magazines such as The New Yorker and Nature Magazine. As a result there is not a single narrative throughout the book; rather the chapters are organized into 3 parts based on themes within. Part 1 explores the origins of the sea, part 2 the movement of water, and part 3 the relationship between humans and the oceans.

Carson’s science writing style is poetic and accessible, and she is able to use this alongside the scientific language to draw casual readers into the oceanography and make them care about the water, rocks, winds and tides. Her style is unique, and of a quality rarely seen in scientific writing today. In the section titled “The Changing Year”, which describes what happens in the ocean through the course of the seasons, she writes:

The larvae of the bottom fauna have long since completed their development and drifted away to take up whatever existence is their lot. Even the roving fish schools have deserted the surface waters and have migrated into warmer latitudes or have found equivalent warmth in the deep, quiet waters along the edge of the continental shelf. There the torpor of semi-hibernation descends upon them and will possess them during the months of winter.

Another thing that makes “The Sea Around Us” so interesting is that, having been published in 1951, many of the oceanographic discoveries Carson writes about were relatively new to her and to science. Unlike Earth’s surface, the majority of which is easily observable, the ocean is not. The pressure of tonnes of water coupled with utter darkness makes deep sea exploration difficult (and expensive). It was only in the 1920s and later that remote sensing technologies developed to a point that the crust in ocean basins could be accurately studied. For example, in the section titled “Hidden Lands”, Carson speculates:

One of the most fascinating fields for speculation is the age of the submarine mountains compared with that of past and present mountains of the continents…What of the sea’s mountains? Were they formed in the same way and do they, too, begin to die as soon as they are born?

The reason for this speculation stems from the fact that the mechanism of sea floor spreading had not been fully developed and explored until the 1950s and 1960s, after the publication of this book (and, in fact, after Carson’s death). We now know that ocean crust is created at mid-ocean ridges, and destroyed in the trenches near to the continents. As for the age of the oceanic crust, it is much younger than the Earth itself and much of the continental shelf – only around 200 million years old.

Or how later, in “Wind and Water”, Carson mentions the 1946 earthquake in Alaska’s Aleutian islands that caused a tsunami in Hawaii, a connection that up to this time was still not fully understood. However, it was after this quake that Carson says “it set people to thinking that perhaps we now know enough about such waves and how they behave that a warning system could be devised”. The United States Coast and Geodetic Survey then developed the method to pinpoint an offshore earthquake’s epicentre and predict the path of a potential tsunami so that communities could prepare. This warning system was used locally as recently as two weeks ago when a 7.7 magnitude earthquake was detected off Haida Gwaii, and within minutes both cities as near as the BC coast and as distant as Hawaii were on watch.

Perhaps the most interesting chapter to a modern day reader would be “The Global Thermostat”, an explanation of the connections between ocean currents, ocean temperatures and the climate of continents over the short and long term. To paint this picture, Carson provides examples of historical climate change from such sources as logs of Viking seafarers and Scandinavian fishers of the Middle Ages. Then she makes the following statement, which could have been written today:

Now in our own lifetime we are witnessing a startling change in climate…it is now established beyond question that a definite change in the Arctic climate set in about 1900, that it became astonishingly marked about 1930, and that it is now spreading in sub-Arctic and temperate regions. The frigid top of the world is very clearly warming up.

The reasons Carson provides for this warming trend include the possibility that Earth is still in a warming trend following the last Pleistocene glaciation, and changes in solar radiation or in tide patterns. It makes sense that natural variation can account for some warming, but since the time the book was written there has been an exponential increase in the rate of warming, primarily due to human factors increasing the amount of carbon dioxide in the atmosphere: burning fossil fuels, ozone depletion, deforestation. If Carson was alive and writing “The Sea Around Us” today, she would most likely have included a discussion of these factors as they would have fit with her ecological philosophy.

“The Sea Around Us” remains relevant 60 years after its original publication despite advances in oceanographic research that make some aspects of the book dated. Through her evocative descriptions that interweave history with literature with science, Carson shows how the importance of the oceans to life on the continents cannot be ignored. This book is a strong reminder that the fight for a sustainable lifestyle that minimizes carbon dioxide emissions into the atmosphere and rubbish disposal into the oceans will never cease to be necessary.

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