EarthTalk recently caught up with writer, sailor, surfer, educator and marine conservationist Jonathan White to find out more about his new book Tides (Trinity University Press, $24.95), in which he takes readers across the globe to discover the science and spirit of ocean tides. In the Arctic, White shimmies under the ice with an Inuit elder to hunt for mussels in the dark cavities left behind at low tide; in China, he races the Silver Dragon, a twenty-five-foot tidal bore that crashes eighty miles up the Qiantang River; in France, he interviews the monks that live in the tide-wrapped monastery of Mont Saint-Michel; in Chile and Scotland, he investigates the growth of tidal power generation; and in Panama and Venice, he delves into how the threat of sea level rise is changing human culture—the very old and very new. Tides combines lyrical prose, colorful adventure travel, and provocative scientific inquiry into the elemental, mysterious paradox that keeps our planet’s waters in constant motion…
EarthTalk: Tides is the result of a twenty-year quest to better understand tides, the science behind them, and their impact on mankind. What sparked your fascination with tides, and a two-decade long exploration of them?
Jonathan White: I grew up surfing and sailing. I always had a tide chart in my back pocket. I knew there were surf breaks that worked only at a particular tide, and reefs I couldn’t sail across except at the highest tides. I knew the moon had something to do with the tide, but that was it. After almost losing my boat during a large tide up in Alaska, I wanted to learn more about this great mystery. I thought I’d get what I wanted by reading a book, but one book turned into two, and two turned into ten. The subject of tides was far more complex and fascinating and poetic than I imagined. I eventually read over 300 books and as many papers.
EarthTalk: Most people understand the moon influences tides, but you write that the science behind tides is much more intricate than most of us know. You call the relationship between the ocean and the moon a “celestial dance” – one that never has a beginning or end – and write the tide is “the moon’s voice on earth, spoken in perfect synchrony.” Can you explain a little bit of the science behind this very beautiful, poetic description?
JW: When I started my research, I thought I would discover a place, or an event, where one could say, “This is where the tide begins.” But there’s no such thing. The tide is constantly moving. Where it’s receding from one coast, it’s rising on another. All this is orchestrated by the heavens – and in particular by the changing orbital relationships of the earth, sun, and moon. So, in a sense, this is a great dance, performed on a very large dance floor.
EarthTalk: One fascinating chapter in the book deals with tidal resonance, something that probably so few people know about. What is resonance, and what effect does it have on the tides?
JW: Resonance happens when something vibrates in response to something else, like how a guitar vibrates when a string is plucked. In that case, the guitar body amplifies the note of the plucked string. This is similar to what happens with the tide, only on a much larger scale. The plucked string, if you will, is any one of hundreds of motions of the sun and moon. The resonating body is the ocean.
EarthTalk: TIDES shows how the history of tides is not just a story belonging just to science or nature, but to mankind. How is the story of the earth’s tides a human story?
JW: The earliest people settled on the coast where food was plentiful and easy to harvest in the intertidal zone – clams, oysters, crab, seaweeds. The written record of these first communities is non-existent, but common sense tells us that their daily lives were shaped by the tide’s comings and goings. They would have acquired, for survival, vast amounts of practical tide knowledge. They would have known, for example, that there was a rhythmic interval between high and low tide, and that that rhythm was related to the moon’s phases. They would have known that the lowest tides occurred during new and full moon, and that was the time to wade out and harvest abalone and urchins, which are normally inaccessible. This kind of practical knowledge is still alive and well among sailors, surfers, scientists, fishermen, kayakers, and millions of others who live on or near the coast.
EarthTalk: You visited Mt. St. Michel, a monastery on the coast of Normandy, France, surrounded by the sea at every high tide and dramatically exposed at each low. What did you learn there about man’s history and relationship to the tides, both spiritual and scientific?
JW: I can’t deny that in some way this was a spiritual journey for me. I knew early on that I wanted to interview the monks at Mt. St. Michel, but they refused my initial requests. It took two years, but finally I got an invitation to a silent lunch and a 30-minute interview. In the end, we talked for an hour, and I learned that they had a strong awareness of the tide’s beauty and mystery. “The abbey,” brother Francoise-Marie said, “is a jewel set in a beautiful case [the bay]; isn’t beauty a language through which God and mankind want to meet?”
For thousands of years, tides were considered a spiritual manifestation of the moon’s divine power. Tide science evolved in tandem with these notions, and the first scientific forays into the subject were performed by astrologers who were keen on confirming the connection between moon and earth, as evidenced by women’s menstrual cycles and ocean tides. We tend to dismiss the role of astrology and the occult in the development of science, but it helps to be reminded that many of the world’s great scientists were also astrologers. Pliny, Ptolemy, Copernicus, Kepler, and Galileo, among others, all labored over scientific theories by day and consulted astrological charts by night. Today, the Kuna Yala Indians, who live on the San Blas Island east of Panama, believe the tides are spiritual messengers from another dimension; they also believe in the science that tells them that rising sea levels will soon force them to leave their 350-island nation.
EarthTalk: You traveled across the globe – from the northern reaches of the Arctic, to the Qiantang River in China to the beaches in California– to witness the largest, fastest, scariest and most amazing tides in the world. If you can choose one, which was your favorite experience, and why?
JW: I went to many of these places more than once. I went to China to see the tidal bore on the Qiantang River three times, to Mont St. Michel and the Arctic twice, and the Bay of Fundy four times. I have no favorites; they were all unbelievably rich experiences, both in the phenomena I witnessed and the extraordinary people I met.
That said, perhaps the most unusual experience I had was slipping under the Arctic ice with Lukasi, an Inuit elder. On an exceptionally low tide, Lukasi chopped a hole in the three-foot-thick ice and disappeared into the dark womb-like cavities below. I followed. It was scary, but the other-worldliness of those couple hours under the ice, gathering mussels and eyeing the rising tide as it started to re-fill our womb, is still haunting.
EarthTalk: In this age of dramatic global climate change, how do tides offer critical insight into the planet’s future?
JW: Technically, tides are a periodic change in sea level attributed to an astronomical force (like the sun and moon). But scientists agree that the tides are influenced by hundreds of other factors, such as weather, seismic activity, wind, and long-term cycles of planetary heating and cooling. We’re accustomed to seeing the tides come and go on a daily time-scale, but if we broaden our perspective, we’d see the tides rising and falling over much longer time-scales. Twenty thousand years ago, for example, the earth was at the peak of a glaciation period, and during that time much of the ocean’s water was locked up in ice. The tide was out, so to speak: sea level was 400’ lower than it is today, and has been rising ever since. The heating of the earth by the last couple hundred years of fossil fuel burning has hastened this rising tide.
In The Edge of the Sea, Rachel Carson writes, “Not only do the tides advance and retreat in their eternal rhythms, but the level of the sea itself is never at rest. Today a little more land may belong to the sea, tomorrow a little less.”
EarthTalk: Many of the world’s most important cities are shaped by the tides. What threat does climate change have on these cities? How are threatened populations preparing for this enormous threat?
JW: We think of the ocean as level, and when we imagine it rising, we see all the world’s oceans rising at once, as it does in a bathtub being filled. But that’s not the case. The ocean isn’t level, nor is it rising at the same rate everywhere. In places like Miami or New Orleans or Bangladesh, the land is sinking as fast as the ocean is rising. That means sea levels are rising at twice (or more) the average rate in those locations. In other places, like Alaska, the land is rising faster than the sea, so the net effect is falling sea levels.
The short and long-term defense against sea level rise is different everywhere, depending on economics, geography, and the urgency of the threat. In Venice, they’re building “gates” at the three entrances to the Venice Lagoon, which will close in a tide emergency. The Thames Barrier, built in the 1980s, protects London, and there are similar defense systems in place in Denmark and Russia. Bangladesh, the Maldives, the San Blas Islands, and some of the South Pacific islands don’t have the finances or the geography to do defend themselves with gates or barriers. They will have to move. Soon.
EarthTalk: What is marine tidal energy, and how have humans utilized this energy for decades?
JW: The oceans are a vast store of energy. Some of it is expressed in the waves we see breaking on the beach, and much of it is in tides and tidal currents. The energy in tidal currents has been harnessed by tide mills for hundreds of years. The earliest may have been in operation at river mouths during Roman times, sixteen hundred years ago. During their heyday, in the seventeenth century, thousands of tide mills across Europe and the U.S. east coast were grinding cereals, stamping copper, sawing wood, pumping brine for salt, and crushing pulp for paper. Communities formed where these mills were built, and life and work were orchestrated by the tide. When the heavy gates of the mill closed with a resounding clunk at high tide, all the community knew it was time to get ready for work. The waterwheel would start turning in a few hours.
EarthTalk: You cite the UK Marine Foresight Panel, which states “If 0.1 percent of the renewable energy available within the oceans could be converted into electricity it would satisfy the present world demand for energy more than five times over.” You also quote Gareth Davies, marine biologist and founder of marine consulting company Aquatera, who says there is enough raw power in the ocean’s tides to equate to, at any given moment, 3,500 coal plants running at capacity. Those figures are staggering. Are there real efforts to translate this power into usable energy? What are the challenges of these efforts?
JW: Yes, there are real – and worthy – efforts, in the UK, Maine, New York, the Bay of Fundy, Alaska, Washington, Chile, British Columbia, Australia, Russia, and New Zealand. Scotland, with its large testing site in the Orkney Islands, may be furthest along. Chile is just beginning, but they have tremendous tide resources to tap.
There are many challenges in the development of tide energy. First, the ocean is a hostile and unforgiving environment in which to work. Tide machines have a lot of moving parts. They’re large and gangly. They break down often, and they’re hard to service. Once below the surface, they must withstand hurricane-like currents and corrosive salt water. The first device tested in the Bay of Fundy, a sixty-foot-diameter turbine that looked a lot like a large windmill, was destroyed in three weeks. “The bad news about that,” said a spokesperson, “is that these machines don’t yet have what it takes to withstand Fundy’s turbulence. The good news is there’s more power down there than we thought.”
Every step of this effort is under development, from blades to gaskets, from hinges to couplers. And, as if the technological challenges weren’t enough, there are the challenges (and frustrations) of obtaining licensing from regulatory agencies, negotiating with reluctant utility companies, securing permits and offshore leases, weighing environmental impacts, and evaluating potential interference with established uses such as fishing, shipping, coastal security, and recreation. That said, tidal energy is clean, dependable, and plentiful. It may not be the silver bullet for future energy needs, but it will definitely play an important and lasting role.
EarthTalk: What are the advantages to tidal energy compared to other sources of renewable energy? Disadvantages?
JW: The tide is more dependable than most other renewable energy sources. Wind is great, but fickle. The sun is even better, but cloud cover can interfere with production. Also, the sun’s energy is available only during daylight hours, and mostly during the summer. Our greatest need for energy is exactly opposite this schedule: we need the most energy at night and during the winter.
Unlike wind and solar, the tide is consistent and predictable. It has its challenges, as I mention above, but in terms of dependability it’s hard to beat.
EarthTalk: Are there locations in the U.S. where we have the potential to harness tidal energy? If so, are there efforts to do so and how supportive is the U.S. government in that venture?
JW: Yes. There are devices in the water and generating electricity right now in New York, Maine, Alaska, San Francisco, and Washington. Generally speaking, the US government is not as supportive of alternative energy as other countries. Despite a few executive orders by President Obama, we have no renewable energy policy. Without this, tide energy, which is expensive to develop, will always struggle for viability among established energy sources such as coal, oil, and natural gas. Elsewhere, like Scotland, the government is very supportive of renewable and clean energy, and has policies in place that offer the needed “push” to develop them.