Peak – Sylphium? Tree? Whale? Oil?

A fellow environmental historian noted the other day that no-one really talks about “peak resource” anymore as part of their arguments for conservation and moderating use of natural resources. That was a big thing in the mid to late Twentieth Century – the world would run out of iron, or oil, or aluminum, or copper, or coal, farmland, or other things. Thinking about it, I’ve not heard that argument used for at least a decade, I think since global warming/anthropogenic climate change became the greater concern. As is my wont the idea sent me down a bit of a research rabbit-trail. Have we humans, globally, ever run out of a resource completely? Not local shortages or failures, but the entire world?

The Roman plant called sylphium (or silphium) might be one of the few resources that westerners used to extinction. And that’s a maybe because a Turkish botanist thinks that the plant might have survived in Anatolia. (Not the genus, but the specific plant). The plant contained chemicals in its resin and sap that affected female hormones, causing abortions or temporary infertility depending on the woman’s condition when she took it. Given what Roman patriarchs did with unwanted children (ordering them exposed after birth) and the risks of pregnancy and maternal death, it’s easy to see why the plant – per tradition – got used up and vanished.

When I came through school the first time, I was taught that the reason for the Industrial Revolution and the switch to coal was because England (and the rest of Europe) ran out of trees. They’d reached peak wood, forcing the shift, which led to the first Industrial Revolution. Or, they ran out of big trees for building and looted North American forests, then ran out of fuel wood, and so on. Well, it turns out that the first one wasn’t true, and the second one was partly true. Managed woodlands in England and Wales provided wood for iron smelting and other uses well into the 20th Century, as it turns out. Cost had more to do with it, both the cost per ton of hardwood charcoal vs coal, and the cost of transportation. Coal measures and seams near water were far cheaper, and provided a steadier, more intense heat, and could be worked more quickly than waiting for wood to grow, season, and then be converted into various fuels. The English had been using coal since at least the Tudor days (1400s), to the point that London passed rules about burning coal in order to preserve air quality. Ship timbers were a slightly different story, because the Royal Navy wanted live-oak and other timbers that had grown in the proper shapes and didn’t need to be pieced, carved, or spliced. England and Ireland were running out of those, and with the mess in the Baltic [thanks Sweden and Russia!] that supply of mast timbers had gotten both expensive and somewhat precarious. So off to North America they went. If the government owns it, you don’t have to pay for it, if you’re part of the government, na ja? And in theory, there was no competition or risk of wood theft.

Whale oil was another resource that almost disappeared. Whale oil and oil lamps were better and cheaper than candles, were more reliable than olive oil lamps, and whale oil could be used for mechanical things that required a very light oil that wouldn’t go rancid as quickly as walnut, olive, and other plant-based oils. It was lighter and less viscous than olive oil, so it could be used in much colder temperatures. Whale oil had a distinct scent (bad) and the odd knack of bleaching fabric that it got on – sort of the opposite of used engine oil. [Or so I’ve been told. Really.] Baleen whales had a different chemical composition to the fat in their blubber, making it much better for most purposes than the blubber of toothed whales. This led to the hunting-out of many whales, to the point of near extinction. However, the search was already on for a replacement for whale oil, preferable something as good as the oil but without the stink-and-stain properties. Rapeseed (canola) oil, petroleum oil, and other things also came into use, and peak whale became less of a worry for everyone except corset makers. They needed the baleen, the ling, flexible filters baleen whales used to separate krill and larger fish from seawater. Then cheap, thin steel appeared on the market, and corsets also switched from baleen to metal for stays.

Then it became peak petroleum, and peak aluminum, and . . . Humans keep finding replacements, or work-arounds, or new sources, or what have you. I suspect that’s partly why we don’t hear about “peak resource” anymore. It doesn’t sell what the environmental activists are trying to do. I firmly believe in recycling what can be recycled, and not wasting things. But I also believe that people will find a solution.

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Topophilia

The humanistic geographer Yi-fu Tuan popularized the term “topophilia” after observing that people from all sorts of cultures around the world tend to identify one sort of landscape as the ideal, and that people do best when we have access to that landscape. One of his observations was that when given their choice, people preferred a gently rolling, well-watered (but not swampy), grassy landscape with scattered copses and clumps of trees. A savanna, in other words, but not flat. The presence of good grass and trees appealed to both herders and farmers, because it shows good soil and steady grazing. The scattered trees provide shelter but don’t block the view, and people like views. They like to see what’s around them, what’s coming.

People relate to our landscape in various ways. We sort out what is good from what is less good, and what is downright dangerous. This over here would be a great farm, that over there should probably stay managed woodland, and avoid that boggy place that smells bad. We fall in love with landscapes, or reject them for a host of reasons. I grew up on the High Plains, which are semi-arid steppe grasslands. The first summer I lived in the Midwest, I boggled at the thick, black soil and the lush grass even in mid-July. Green ditches are not natural. Ditch grass is brown. But in that part of the world? It is a wonderful landscape that has to be maintained by people, or large areas revert to wetland and marsh. Other parts would become forest. The landscape today is flat to gently rolling, with clumps of trees, large swaths of domestic grasses, and semi-managed watercourses. Sound familiar? It’s beautiful, fertile, prosperous, and a bit rough during winter, with the occasional tornado, derecho, and giant hail in summer.

One of the things that Yuan tried to impress on people, especially urban planners, is that people need greenspaces. I remember reading an account from LA, where well meaning urban planners descended on a ghetto/barrio area with designs for a community center and pool and other amenities that would benefit residents. The residents informed the planners in no uncertain terms that they did NOT want another swath of cement that happened to have a pool and community center. They wanted trees, and grass, and growing things. This was in the ’60s, when the concrete and steel school of urban landscaping and city planning was still hanging on. In this case, the planners listened, and after to-ing and fro-ing, a new urban greenspace appeared in the form of a park with some trails and sports fields and trees. A savanna, in other words.

All people related to our environment in some way. We may reject it and seek another, we may sample a variety of landscapes and decide on a particular one where we want to dwell, we change our current surroundings in order to better fit what we prefer. Some people try to shape landscapes (notably urban ones) in order to remake society in the image they prefer. Others attempt to put the environment under glass, to preserve a perfect “pristine” world that never actually existed, and that is not stable. If there is weather, and sunlight, and the occasional plant, you cannot have an unchanging “climax state” in the ecosystem. In fact, the idea of climax states has gone out the window. We may prefer the land to be a certain way, but often we have to keep it so by burning, or irrigating, or draining, or adding trees, removing trees . . . We’re as bad as beaver and bison, except we have thumbs.

“You Darkness that I Come From . . . “

Darkness, night, dark nights of the soul, following a star in the heavens, comets as portents . . . What does it mean if all of that goes away? Both in terms of astronomy and interesting people in star-gazing and studying the heavens, and in the sense of culture and religion? Those were some of the topics batted around at one of the FenCon panels.

The title phrase comes from one of Ranier Maria Rilke’s letters to a young poet, in which he (Rilke) muses about preferring darkness to firelight, because night includes everyone, while light shuts out those beyond the glow. I confess to having always been one “acquainted with the night,” as Robert Frost phrased it. I grew up star-gazing, taking walks after dark, going on Owl Prowls at the nature center, and so on. I prefer to keep lights dim, even as my aging eyes are less sensitive to light in general. I grew up understanding all the star references, and learning celestial navigation, and so on. But what about generations that can’t see stars, or anything dimmer than the quarter moon, because of city lights?

For astronomers, to lose the stars is both sad and a professional problem. Who will pick up the mantle after the current generation retires, if younger people don’t learn to look up, and are not fascinated by the wonder of “what’s out there? Why does it look like that?” Light pollution is a serious problem for migrating birds as well, in some cases. It can be a real pain for pilots, because finding the airport in a sea of lights is Not Easy if you don’t already know what to look for. Especially if you are not on an instrument approach with everything set to get the radio beacons or GPS fixes. There’s a runway down there. Somewhere. Or is that I-80?

Some people reply to the plaints with “There’s an ap for that!” You can point your phone or tablet at the sky, or ground, and get a star chart for whatever you are aimed at. Hubble and Webb telescope images are far more colorful and detailed than what you can see through a 6″ backyard telescope or binoculars. And some places still have a planetarium, to simulate going out at night without the bugs, traffic, light pollution, stiff neck, or risk of mugging. Who needs real stars?

We humans do. We need darkness to properly rest. We need to be reminded to things outside of our ken, of worlds greater than ourselves. There’s a sense of wonder and amazement kids and adults get from seeing the stars and identifying the patterns and shapes, the nebula and galaxies and planets, that even a great planetarium can’t quite match. There’s no ap that will reveal the heavens in their glory on a cold October night in Yellowstone, when so many stars filled the sky that I couldn’t identify constellations or planets. The Milky Way cast shadows, it was so bright. Or out at Black Mesa, Oklahoma, as the summer stars marched across the peak of the heavens and a coyote or ten called back and forth.

Darkness stands for evil in many religions. Darkness is when bad people lurk, and thus when heroes do their thing. Humans generally don’t see as well at night as by daylight, although there are a lot of variations on “not as well.” We don’t see color, and discerning patterns and “is that a shadow or a hole” becomes a bit more challenging. Not that it stopped people from working, traveling, or doing things at night in the past. Today, we flood the night with artificial light to make travel (in vehicles) safer, to discourage footpads and robbers and other mischief makers. We fear darkness more than in the past. Which came first – not going out into the darkness, thus leaving it for evil to use for shelter, or evil growing in the shadows and chasing “good people” indoors when the sun sets? Yes?

St. John of the Cross reveled in night, in his extended poem and meditation “Dark Night of the Soul.” Night brought the lover (G-d) and the beloved one (the mystic) together. Night is for lovers, for philosophers, for socializing. Night holds sweet secrets, conceals private pain from those who would mock or minimize what is very personal and real. Night is greater than we are. Darkness and stars, the moon and planets, remind us that we are tiny creatures in a big, mysterious, wonder-full universe. Who made the moon and hung the stars? What are the stories of the shapes in the night sky?

Without stars, we humans lose both astronomy and spiritual wonder. At least, that’s what the panel and those present eventually drifted toward, although no one said it in those words.

Book Review: When the Sahara Was Green

Williams, Martin. When the Sahara was Green: How Our Greatest Desert Came to Be. (Princeton U.P. 2021) Kindle Edition.

Once upon a time, millions of years, tens of thousands of years ago, the region called teh Sahara was green. Sometimes it held enormous rivers. Volcanoes erupted, were crowned with glaciers, and fell silent. Huge fish swam in the giant lakes and rivers. Lush vegetation of varying kinds grew on the land.

Then something happened. Actually, a very large number of somethings, including the entire continent moving in such a way that tucked the Sahara into a dry swath of climate, and Europe (the landmass) cutting the moisture supply to the northern regions. All long before humans ever wandered the landscape. So, as Dr. Williams points out, you can’t blame humans for the desert. Which may be the most useful point in the book.

Martin Williams is a geologist who specializes in deserts and how they got that way. His first introduction to the Sahara came in 1970, when the group he was with couldn’t go to Libya because of a coup in progress, so they went to an even drier region instead. As he and the group leader went ahead of the others (on camel, as the others got the Land Rovers and other vehicles repaired), Williams noticed evidence of human presence, and of a river, in a place where no water could be seen. That made him curious, and the rest is this book.

Half geology and half travel, the book is a very readable account of the Sahara’s deep history, going back to the Cambrian. It has nice maps and diagrams, although more would be useful, especially in the e-book version. The illustrations are hot-linked, as are the end-notes, so you can go back and forth, but that gets tiresome so I just studied the major diagrams and memorized what was where. Williams has a knack for translating from geology into good prose, and blends the deep past with more recent explorations and observations. He works roughly chronologically after the introduction, going back to the Cambrian and moving toward the present climate regime.

Contrary to popular understanding (and most nature shows I’ve seen), the Sahara is not an endless sea of tan dunes. About a quarter at most of the land is sandy. This is in part because sand is needed to make sand, and large swaths of the area don’t have the right rocks. More common are huge rocky “pavements”, and clumps of hard, black or red hills. Some are volcanic, some are tougher sedimentary remnants (think Ayers Rock/Uluru in Australia). Volcanoes in East Africa played a role in drying the region, blocking flow from what is now the Indian Ocean. Africa moving north to collide with Europe, closing the Tethys Sea, didn’t help, since what is now the Med has gone completely dry, most recently during the last phase of the Ice Age. Then things improved until the Younger Dryas, before returning to the current arid phase.

The edges of the desert move. This is not, as Williams points out, because of overgrazing, slash-and-burn farming, or air chemistry. It is because of changing rainfall patterns linked to the North Atlantic Oscillation and the El Niño/Southern Oscillation and Indian Ocean monsoon. How are they connected? No one knows yet, but there are a lot of guesses. In wetter phases, the North African grasslands and brush move south, or the sahel region moves north. When things dry out, the Sahara grows once more.

Humans didn’t cause this, but modern governments can make things worse for the people of the desert. Ordering Bedouin and others to stop moving, even when drought moves in for a decade or two, causes misery for the nomads and for the farmers around them. Killing off livestock “to stop overgrazing” isn’t the best answer, per Williams. Understanding the actual reason for the drought, and making space for people to respond in ways that work, is the better solution.

Williams is concerned about human effects on the environment, but he’s not pounding the “two legs bad, four legs good” drum that so many do. I suspect his background being in geology makes the difference – he’s used to looking at the looooooooong term. He talks about the humans who lived in what is now the desert, how they coped with the gradual changes and shifts, and what we know and don’t know.

I highly recommend this book. You don’t have an earth-science background to enjoy it, but it does make for faster reading. The illustrations and charts are good, and there are lots and lots of endnotes for those who want more.

FTC Notice: I purchased this book for my own use and received no remuneration or consideration from the author or publisher for this review.

Not Repeating, But Rhyming

China and western Europe have drought. The previous year had flooding and cold. Eastern Europe alternate hot and cool. Parts of North America are dry, then drenched, while other parts get warm for extended periods. La Niña has dominated the ENSO pattern in the Pacific for two years now, and may go neutral or shift to El Niño after February.

We’ve seen this before. The 1200s and early 1300s, the early 1600s, low solar energy output augmented by a bunch of tropical volcanoes going off, with the Italian volcanoes and Iceland’s Katla tossing out their own contributions, caused a massive climatic downturn in the northern hemisphere that led to some of the worst-for-humans weather patterns in centuries. Cold and wet, hot and dry, floods and rotting crops, summers with hard frosts in June, droughts that dried the Yangtze and Yellow Rivers, plague and other disease outbreaks, civil unrest and regional wars . . . The Seventeenth Century stank worse than rotten eggs and a dead cow in a confined space in August. And it wasn’t because of CO2 or the internal combustion engine. It was the internal combustion of the sun and some volcanoes.

El Niño and the North Atlantic Oscillation are patterns. They don’t repeat on set schedules, because there are far too many variables, only a handful of which climate and weather people are 100% sure about. To make things more complicated—as if Nature needed help!—there are connections between the snowfall and rain in East Africa and the El Niño pattern. We just have no way to know how it works, but we know it is there because of the enormous Nile flood calendar. Climate specialists can cross-reference written and proxy data from South America and Southeast Asia with the Nile flood records, and there is a clear pattern.

What we can’t predict are volcanoes. A massive volcanic eruption in what is now Indonesia probably played a major role in the weather shift that triggered the rodent population explosion that led to the Plague of Justinian as well as the cold, wet, stormy weather that battered north-western Europe in the 500s. Nor could we predict the spate of tropical volcanoes in the 1300s and 1600s, or the Year Without a Summer (Mt. Tambora, tone it down!) The right volcano in the wrong place can cool things considerably. Mt. Pinatubo in the Philippines dropped global temps by 1-2 degrees C for a year or so.

Nor can we pinpoint forecast what will happen exactly where. Eastern Europe might be slightly above average while Western Europe and Britain freeze. Or bake. A heavy winter with lots and lots of snow might be followed by a hot summer and drought. We can guess trends based on recorded and past oceanic temperatures and winds, but all forecasts are odds. My part of the country has good odds of reverting to average-for-the-past-thirty-years rainfall if next year is an El Niño, because that shifts the storms patterns south, more directly over this area. But that’s averages, not “RedQuarters will get 22 inches of rain between February and November.”

So if I seem a bit mellow about the latest “sky isn’t falling and it’s all the fault of the Global North minus China,” it’s because I’m looking at the long patterns. No, it isn’t any comfort when my water bill skyrockets as I try to keep the grass not-entirely-dead or the gas bill zooms because of Snovid ’21: Part 2 the Sequel. (We only got down to -4 F, with windchills of “miserable.” And up here we had rolling four-hour blackouts on a schedule, not the weeks without power like down-state.) Nor do I envy Europe if the predicted effects of the Tonga volcanic eruption do cause colder weather on top of the usual chill. Is it all mankind’s fault? Only if we’ve figured out how to trigger volcanic eruptions, or how to dim the sun, and I do not refer to adding fine particulates to the atmosphere, or putting mirrors in space to reflect “excess” solar energy.

I still don’t like drought, or blizzards, though.

Loving a Dry Land

I’m strange. My favorite places to live are all semi-arid, which means that most of the time, they are hard lands to make a living from. “A semi-desert with a desert heart” as Marc Reisner described it, wet years are followed by hard-scrabble half-centuries of dust, fire, and struggling to find water and to keep the wind from stealing that water. And when it does rain, mosquitoes fill the grass, low places become bogs, snakes move uphill and indoors, and people get snappish and moldy on the north side. We’re too used to the very sun we curse, grumble at, and hide from.

But I love this part of the world. I can see weather coming, even if I can’t get away from it. There’s nothing to hide behind once you get away from people and the trees we’ve planted. The Llano Estacado is one giant emergency runway, the few canyons excepted. At night, stars cover the world from here to there, making navigation easier once you know how to sort out which stars you need. Bison and cattle thrive here in wet years, growing fat on the short grasses of the prairie and the medium-height grasses of the playa lakes. The constant wind drives pumps and household wind-chargers, dries laundry, and keeps the mosquitoes at bay. Mold and mildew are uncommon, although turning into jerky and/or getting kidney stones are a constant concern.

In the mornings, meadowlarks and mocking birds, redwing blackbirds, and white-wing doves serenade the world. Wild sunflowers face east, welcoming the sun. In summer, Mississippi kites launch with the first thermals, soaring up and up to find bugs. Larger raptors also linger, Coopers hawks, a few golden eagles in the canyons, vultures (aka “the county hygiene society”) wherever they choose to congregate.

Foxes and coyotes trot among the grasses, blending in as they hunt rodents, grasshoppers, locusts, and anything else that looks edible. Mr. No-shoulders slithers here and there, bullsnakes and rattle snakes and other things that discourage you from putting you hand into holes. The occasional mountain lion and bobcat meander through, and pronghorn antelope race along, diving under fences to get away from the overly-curious.

When rains come, and winter fades, the land can look like knee-high velvet. The wind hisses and mutters over the flat land, bending the playa grasses as it passes. Cloud shadows flow as well, darker patches on greens and browns. Wildflowers appear in pockets, and wild sunflowers loom come late summer. As the days grow short and the rains fade away after the equinoctial storms, the grasses cure, brown, seed-heavy in all their forms. They are rich fodder for cattle, and for flame. March is fire month if the rains do not begin, or if snow has not fallen. Trees are rare and valued, those that can tolerate heat and cold, constant wind and hard sunlight on alkaline soil.

I love the high plains. It’s not an easy place. It’s not a “pretty” place. But it’s home. If I ever have to leave, I will miss the land and the people.

About that “Rewilding the World” Fantasy . . .

So, I was skimming cover copy at the regional B&N recently, and found yet another, “humanity goes away and paradise returns,” this time with terraforming gone wild tossed in. Yawn. Now, granted, I did not buy the book and read it, so I don’t know all the details of the world building, either in-book or otherwise. However, if there were dams and irrigation systems, a rapid decline in population will not lead to a return to Nature. The opposite. Because we (humans) have seen this before.

One of the big surprises that arose when people got serious about using the tools of archaeology and hydrology for environmental history was the realization that the end of the Roman Empire and the population decrease in certain regions led to vastly increased erosion. That was completely counterintuitive. The thinking had been that when people stopped cutting down trees and overgrazing, and when the irrigation diversions silted up and went away, erosion would return to the pre-development baseline, then improve (build up instead of cut down.) That’s not what the dirt showed. Oops.

How awkward.

For one thing, in a lot of places, the “forest primeval” hadn’t existed since the Neolithic. Humans abhor dense, dank wildernesses. So they cleared out spaces for desirable species, thinned the undergrowth, encouraged “good plants” and generally did everything they could to get rid of “pristine Nature.” Unless it was the high mountains, or nasty swamps, people all over the world modified, improved, and tweaked “Nature.” And that’s before the engineers appeared . . .

When you deal with water control structures, like flood-control dams and irrigation systems, you generally have to keep in mind silt and other sediments. Silt, the very fine particles of soil and other things, will slowly settle out of slow moving or non-moving water. Give it long enough, and it will fill-up your reservoir. Moving streams have an energy balance: Slope of bed X volume of flow = amount of sediment X speed of flow. Change one and the others will adjust to balance. So if you slow the flow, silt settles out. Speed up the flow of non-silty water (say, at the outlet of a dam), and you will have increased erosion until the water collects enough solid particles to return to balance. Fast moving water can carry more stuff than slow moving or still water. It’s common sense, but the ratio wasn’t known until the late 1800s-early 1900s.

So, back to the Roman water systems. When Rome retreated, the engineers and excess population needed to justify keeping the dams and irrigation systems working also went away. So the systems failed from floods, lack of repair, the occasional sabotage, and hap-hazard maintenance. All the dirt in the ponds behind the dams started to flow downstream, silting up the place. Irrigation systems became erosion channels, eating into older fields, especially if terracing failed as well and gravity helped move soil down the slopes. The greatest amount of erosion seen in parts of Europe prior to the 1800s came between AD 460-600 CE. When the population dropped and resource use declined, in other words. Reforestation didn’t happen fast enough, and the bare soil that had been fertile fields washed away, causing more erosion until it was reclaimed in the Middle Ages.

That’s the problem with archaeology and environmental history. We keep finding things that make simple, tidy stories messy and complicated. We upset Natural apple-carts. So a failure of terraforming leading to the disappearance of the human colonists would not return the planet to “pristine Nature.”

Ya know, studying environmental history ruins so many sci-fi and fantasy concepts. SIGH.

Whither the Trees?

Several of you have commented on the lack of trees in the photos I’ve uploaded. We tend to assume that England, Scotland, and associated areas were covered in forests, like Nottingham Forest where Robin Hood hung out, or the “forest primeval” or “England’s green and pleasant land” of fields and leafy, shady woods. Loreena McKinnet’s “Mummer’s Dance,” Kipling’s “Tree Song,” other things give the impression that England and Scotland were well forested until, oh, the 1500s or so, when a wood crisis sent the Royal Navy to the New World looking for ship timbers. Oh, and the Industrial Revolution 1.0 started because of a fuel crisis. At the same time, greedy landlords cut down all the remaining trees, just like in the US after 1800. Except . . . well, yes and no.

If we roll back to the end of the last Ice Age – 15,000 to 12,000 years ago (southern England vs. northern Scotland), we’d find very few trees, more tundra and grassland. On, and the British Isles were still connected to what is now mainland Europe, and the ancestral Thames River flowed in a valley between them. As the ice retreated in fits and starts, then all at once, trees began moving back into many places that had lacked trees. The sea also moved in, and at one point, once Doggerland (now the English Channel) flooded, the Forth River and Tay River were sea lochs as far inland as Sterling.*

England and Scotland and Wales don’t have many Paleolithic sites. It appears that people came, then got chased out by advancing cold, then came back again. What sites have been found tend to be on what is now coastal Norfolk, and south in Sussex, Kent, and parts of Wales. It was hunting and gathering, with seemingly long periods of de-population between advances. Some of this might just be absence of evidence, but Scotland in particular was still inhospitable because of glaciers and ice-sheets. Any human habitation would have been on the margins, where migrating animals passed.

By the Mesolithic (9,000-4,500 BC/BCE) we start finding semi-permanent settlements of gathering hunters. These people are building structures and leaving more evidence for their presence. The tundra and taiga are shifting into temperate forest, first pines and cold-tolerant scrub, then slowly deciduious forests fill in the warmer areas before advancing north. We can tell because of changes in pollen core samples from places like Star Carr (major Mesolithic settlement) as well as actual finds of worked stone and in some cases, preserved wood, bone, and leather. People are using the woodlands, but are not clearing large areas yet. The “agricultural revolution” of the Neolithic has not yet arrived, but people are shaping the landscape to an extent already as they move inland, mine, and select trees they like.

One older argument for “there were trees until after Rome” came from archaeologists who didn’t think that a stone ax would do much damage, and would require too much effort to make forest-clearing probable. In the 1960s, experimental archaeology came onto the scene as people decided to actually “try it,” with “it” being a lot of different things. As it turns out, swidden field clearing works even in damp places like the British Isles. You cut down small trees, girdle the big ones, and then wait. Structures like “sea henge” and the wooden henges on Salsbury Plain also prove that people were indeed willing and able to cut down very large trees, or even root them up and invert them into ritual structures, despite not having steel axes and chainsaws.

The Neolithic, Chalcolithic, and Bronze Age are when the forest primeval gave way to the ax and firebrand in England and Scotland. Farming requires space, and wood. Lots, and lots of wood. If you can’t make it of leather or stone or bone, you need wood. Wood for houses, tools, fuel, boats, buckets, fences, trackways through wet areas on major routes of trade and/or worship (see the Sweet Track), religious images . . . The forest started to get thinned, then removed for arable (farm fields) and pasture. Warmer climate also helped chase the forests into the uplands, with elms in particular losing prominence in the pollen counts.

At the same time, people began practicing what we’d consider renewable forestry. They made living hedges (one of which seems to be 3000 years old!) that provided shelter, berries, and some types of small wood. They began to coppice and pollard trees, providing wood for tool and fuel use that constantly regrew. They made some use of coal, but not much yet. Customary rules about who could gather wood and when seem to have developed as well, but archaeologists and anthropologists (and environmental historians) are debating that as I type. The upshot was, by the time of the Romans, and especially by the AD 400s-900s CE, England and Scotland looked a lot like they do today – intermittent batches of woodland and trees, with pasture and fields between. The huge swaths of pines in Scotland are WWI-WWII era, and are a source of much debate, since they are bio-diversity deserts compared to mixed forests or properly managed pasture.

*You can’t really argue with the bones of stranded whales that are only 5-6K years old.

Removing Dams: The Good, the Bad, and the Messy

“Set the river free” is a cry heard more and more often. It started in New England, when old, unused water diversions and containment structures were removed, often for good reasons, from smaller streams. The goal was to let the stream or river return to as close to original as possible, or to prevent a dam failure and the subsequent floods and damage. If the thing doesn’t serve a purpose, and might even have become a hazard, why not take it out? And again, in some cases, it made good sense. In other cases people took sediment samples from behind the dam and said, “Hold up a second! We don’t want this in the river.” And so the dam stays for now.

However, there’s a difference between a little mill-dam or a small diversion on a stream in what has reverted to forest, and a good-sized power dam, or flood control structure. And you can’t just “rip it out and let the river heal.” Depending on the dam, the river, and what’s down stream, that can lead to disaster, at least for the very aquatic life that people are trying to save/reintroduce.

So, a quick primer on what happens behind the dam when the water flow is greatly slowed or stopped. A large puddle forms, growing into a pond or lake. If the river carries lots of sediment (silt, sand), then the heaviest of that begins to settle out into the bottom of the lake. As the lake fills, the weight on the ground increases, as does pressure on the dam and the sides of the lake. If excitement is going to happen, this is when the first signs appear (Teton Dam is the horrible warning). A little seepage is pretty common, and should be clear. If muddy water starts appearing on the wrong side of the dam, then Things Need to Be Done. If all goes as planned, a lake fills in behind the dam. Hydropower dams use the pressure of that water to turn turbines that generate electricity, so they are always releasing water, or do so intermittently to meet peak demand. Irrigation dams draw-down water levels in the dry season for farmers to use, then allow levels to rise again in the wet. Recreational dams hold water at all times, unless there is a compelling reason to release water (controlled flooding as opposed to uncontrolled “it ate the dam!!!” flooding. See Johnstown for the horrible warning.)

Over time, if the stream carries enough silt, the lake might just turn into a mudflat with a waterfall on one end. That is very, very rare, at least in the modern era. You can see it with ancient structures in Arabia and a few other places. Eventually the dam wears away and you have to look very carefully to see that a water control structure ever existed. Most modern US dams have a life-time of about a century or so before something needs to be done about the silt, it silt deposition is a problem. Something like Hoover Dam or Glen Canyon? Not such a problem.

So, let’s say you want to tear out a mill-dam on a rocky stream that never had much sediment. You do a core check of what’s behind the dam, find nothing toxic and no huge slugs of sediment, and decide to get rid of the structure. Some sludge and gunk will flow downstream, so ideally you allow a slow release and everything keeps going until the sediment reaches the sea (or the next lake downstream) and you have a nicely restored river. You are happy, the land owners are happy, and the fish are happy. Good deal.

However, let’s say you look at a dam downstream of an industrial area. It needs to go. So you take a core of the yards’-deep sediment behind the dam and Whhoooooooah Nellie! Arsenic, dyes, lead enough to rearm the Ottoman Empire, and a few other things have accumulated. Do you really want that going downstream and settling all over the stream? Probably not. The better thing to do is to lower the dam, allowing increased flow-through but still keeping that “stuff” penned up and out of circulation until someone decides they want to pay for the removal and remediation.

So, what if there’s been no, zip, nada industrial development in the area, ever. Your core comes out clean, but full of sticky, silty, sludge. The flow in the stream is not what it used to be, for a number of reasons. If you rip out the dam, it will take a very, very long time for that material to get through the stream. Most likely, the stream will aggrade, getting shallower and wider, leaving the sediment over the current bed. It can also cause the shallower water to be warmer for a while, until the balance starts to return after more sediment is carried downstream. If you have really good trout fishing downstream, this is probably not the scenario you want. Now you start talking about dredging out the stuff, taking it somewhere else, and then opening the dam after the water settles again. $$$,$$$,$$$.00 can be involved.

So, OK, what if we just rip out Hoover, or Grand Coulee? Well, first, where is that electricity going to come from? Nuclear is the only close replacement, because wind and solar are not going to work. Second, that will be an enormous slug of very, very cold water racing down the Colorado River valley and taking a lot of stuff with it. Like downstream dams and diversions. Like any water-supply intakes. The fish will be in for a surprise with that temp, although the modern Colorado is far colder than it once was. And eventually the sediment will start to move, slowly, and you will get back to closer to the old Colorado, brown, wild or sluggish, and meandering. If you get/got drinking water from downstream of Hoover, well, buy a lot of filters and plan on changing them regularly. And get ready for floods, as the bed, once scoured, starts to rebuild with that sediment.

Did I mention floods? Annual or semi-annual floods will return. Any valuable infrastructure will have to be relocated, or turned sacrificial. You’re going to lose habitat for some creatures and gain it for others. Given the sediment that’s built up behind the dams of the 1910s-1950s, anything that needs a rocky bed with well-oxygenated water might have difficulty for a while, depending on how quickly the sediment is redistributed and filtered out as the balance in the stream resumes.

Note: All these are controlled removals. Nightmare fuel is if one of the big dams on the Colorado goes all at once, because then the downstream dams will likely go as well. The Colorado will reach the sea again, perhaps by a different route. Or it might refill the Salton Sea and a few other areas, then head out via LA or even double back and then go out to Baja. The loss of life would be tremendous, the loss of infrastructure eve more so.

So dam removal can be done, and done right. However, “rewilding the Columbia and the Colorado!” is probably an undertaking best left to fiction writers for now. Until nuclear reactors become far more common, and we know a lot more about what’s behind those structures and how to release the contents slowly, we could do far more harm to the environment than we ever did by building the dam.

Yep, I’m a History Nerd

. . . I got excited to see that Ole Benedictow has updated his book on the Black Death. The new book is only 1060 pages! On the other hand, it is priced, ahem, where you’d expect his publisher to price it, so I’ll stick with my “merely” 600 page older edition.

. . . I was asked “What’s your favorite time period?” and I started to reply “environmental history,” which isn’t a time period. I settled on “I don’t have one, really.” I’ll devour environmental history from pretty much any era, any continent, and any sub-field, although water history is always my first love.

. . . I caught myself critiquing the casting of a movie because one character looked too old and another was too much like his historical counterpart. Then I remembered “This is the late 1600s. These guys are all adults and then some!” And I giggled, because . . . the wigs. Oh, the wigs. Yep, very late 1600s – 1700s. You really do get a sense for the overstuffed formality of the Habsburg Court. (The film is the Italo-Polish production The Day of the Siege, about Vienna in 1683. It’s not quite what I expected, but it works.)

. . . I can almost justify more Sabaton stuff because “It’s historical.” Almost.

. . . I have strong opinions about certain periods of history, and certain schools of historical philosophy. And will go on at painful length about them unless stopped by an outside force, or all my listeners fall asleep on their plates.

. . . Yes, I read all of it. And of that one too. I’m still working on that one (600 pages or so left to go).

. . . I forget that normal people don’t get wildly excited about new translations or publication of documents from [obscure historical period or location].

. . . I’ve said, “I need to fill that hole” at least once a year for the past decade or two, and I’m not talking about the yard and gardens. Thus books on the economic history of China, the environmental history of China, environmental history of Africa, the one on preColumbian landscapes and environmental management of California, the comparative frontiers of South Africa and the US West and Mexico, and an intellectual history of Communism. Most of them I’ve finished reading, a few still need to be finished.

. . . I read geology and archaeogenetics as escape reading. Along with fiction.

. . . My recommendations on Amazon.de are, let us say, eclectic and heavy on obscure histories that look really fascinating. (We will not discuss shipping costs.)

I think, at this point, I’m hopeless. Which comes as no surprise to anyone who has set foot in my house and seen the two stacks of “I’m in the process of putting them back” books by the front door. One stack of which has sat for so long that I need to take them back to school, because we’re going to be starting that topic again soon! Oops.