Photo by Michael Denning on Unsplash
There is the story and then there are the facts supporting the story. The story is how you know that climate change is happening here and now and is impacting people like you. The facts are how you know how those impacts happen and what they mean for the future.
We need both.
Saltwater Intrusion
My husband’s best friend is a farmer in Talbot County, Maryland, on the edge of the Tred Avon River. I’ve written about him before (here, for example), but I leave out his name because I haven’t asked his permission to use it. He’d probably say yes if I did ask, I’m not going to reveal anything private or embarrassing about him. The thing is that there’s a marshy tidal gut running through his land, and a row of trees grows along the edge of that gut, but up away from the marsh, where lawn grass grows. You pass these trees on your way in to his house.
Those trees are dying.
They’re not dying all at once, more like one or two at a time, starting with the ones closest to the water. He knows why. It’s the salt from the river, which is quite brackish there. The tides are getting higher. It’s probably getting saltier, too, though I haven’t been able to confirm that. And even though the tides don’t rise high enough to wet the trees (except perhaps in storm floods), the salt is moving underground.
That is salt intrusion. And it’s only good luck that it’s only threatening the trees along the driveway, not our friend’s crops–or his well. Not all farmers in the Chesapeake region are as lucky, and nobody can be lucky forever.
This is what climate change looks like, or one of the things it looks like, anyway. It’s not always sudden catastrophe, an it’s not always far away or in the future. Its effects are usually mixed up with the effects of other issues, such as land use practices, state or national policy, or unrelated geological processes. What’s important to know is that climate change is part of the problem, and stopping climate change must be part of the solution.
Let’s talk about salt. Let’s talk about the rising seas
The Ins and Outs of Sea-level Rise
The short version that lots of people know by now is that as the global climate warms, ice in Greenland and Antarctica melts, adding more water to the ocean and making sea level rise globally. That part is true, but it’s not the whole picture, and it doesn’t explain all the sea level rise we see here in the Mid-Atlantic, including in the Chesapeake Bay region.
How the Water Rises
Melting glaciers put more water into the ocean, but thermal expansion (most things expand as they warm up) means even the water already in the ocean is growing. In fact, thermal expansion is responsible for a greater proportion of sea level rise so far than glacial meltwater is.
Photo by Jonathan Ford on Unsplash
Expansion and melting together raise sea levels globally (by about nine inches since the late 1800s, or almost six inches since 1950), while regional or even local factors either raise sea level even more or counteract the global rising. For example, during the last ice age, the North American continental glacier was so heavy that it pushed the land beneath it down, bulging the land to the south up to compensate. That glacier melted away over ten thousand years ago, but land moves slowly, so the area that was under the ice (the northern half of the US, plus Canada) is still slowly rebounding, while the area just to the south slowly settles. That’s why the New England coast is slower-than-average sea level rise, while the Mid-Atlantic is seeing the sea rise faster.
Other mechanisms influence sea level, too, locally or regionally, including ocean currents, wind patterns, and even gravity; the glaciers on Greenland and Antarctica are so big, their gravity pulls the ocean water closer, raising sea level along their coasts. As those glaciers shrink, their pull weakens, and the water drops slowly away, sloshing backward into other regions–such as mine.
The Delmarva Peninsula has some of the fastest sea level rise in the world–double the global average–because so many different mechanisms come together right here. Many areas also have a lot of local erosion, meaning we lose land to the water even faster. While some might be tempted to say our loss of land is due only to erosion, the fact is sea level rise makes erosion worse.
Why a Few Inches Matter
All these mechanisms of sea level rise together add up to ten inches of rise at Annapolis, Maryland just since 1950, almost double the global average, and the rate is speeding up. I haven’t found figures going back to the 1800s, but based on the global figures the water must be at least 13 inches higher now than it was when a lot of the basic regional infrastructure was planned out.
Ten inches doesn’t sound like a lot–but context matters. Consider that these inches are added on to each coastal flood event, meaning each flood is ten inches higher than it would have been, and that during a flood the difference between being OK and having saltwater in your living room could well be only a matter of inches.
It’s not the average water level that matters so much as where the water is on the highest tides or during storms. When the wind blows onshore and the full moon pulls the tide high, docks go under water. I’ve seen this–it doesn’t have to be a storm, just a blustery day. Saltwater puddles on low-lying roads, pushes up through storm drains…. A road or a yard or a parking lot doesn’t have to be underwater all the time to become unusable, it only has to get wet once too often. There are places in the Mid-Atlantic where that is already starting to happen. There are other places where it is about to happen.
And then there is the salt in the ground and what it does to forests and farm fields.
How Saltwater Intrusion Happens
Photo by Kelly Sikkema on Unsplash
There are a couple of different ways salt can intrude where it didn’t used to go.
During coastal flooding events, salt soaks into the ground. The salt persists long after the flood drains away. Eventually rainwater will wash the salt out, but not if the floods come too frequently. After repeated flooding, the ground can actually get saltier than the sea.
Alternatively, salt can come up from beneath. Fresh water floats on top of salt water, so rivers flowing into the sea are sometimes salty near the bottom and fresh at the surface. Similarly, groundwater is often salty near the coast or along the shoreline of an estuary, especially deeper down–a layer of fresh groundwater may lay on top. As the sea rises, not only does saltwater move farther inland along streams and rivers, but it also moves up vertically, an invisible sea level under the water or under ground. That’s how wells can turn salty. It’s also how trees and crops can die of salt even if they haven’t been flooded–the freshwater layer on top of the salt in the ground is shrinking as the salt rises.
A related problem is that as the salty water table rises, drainage in the land above starts to get poor–there’s nowhere for rainwater to go. At that point, if there’s salt in the ground from flooding, it can’t easily be washed away by rain. The moisture stays put into it evaporates, leaving the salt still there.
Drainage ditches often make the problem worse because they make it easier for salty water to flow in on high tides, and from there the salt soaks into the ground.
The sea is not the only source of salt–road salt washing off into rivers is a significant problem in some areas, too–but in coastal areas, especially flat coastal areas like Delmarva, sea level rise is the primary source of the problem.
How Saltwater Hurts
Salt can act directly, almost like a poison, or it can act indirectly–salt chemically strips nitrogen and phosphorus out of the soil, leaving it infertile. And because those nutrients then wash into waterways, it’s possible saltwater intrusion could ultimately increase algal blooms and related problems. Rising salt levels in drinking water not only makes the water itself less drinkable, it also damages pipes–the Flint Michigan water crisis was caused by slightly salty river corroding old pipes, releasing lead.
The issue isn’t black and white. It’s not that one year a crop field is fine, the next year it’s a giant salt shaker. What happens is the salt concentration in the soil slowly starts to rise–it’s often worse in one part of a field than another–and yields start to drop. Some crops have trouble sooner than others; corn, for example, has a very low salt tolerance, while soybeans can handle much more salt. Some less popular crops, such as barley, are even better. Eventually, farmers need to either switch to a crop with a higher salt tolerance or stop planting the effected area. A complication is that it’s not usually possible to know when an area has become too salty without planting it and losing the crop, and expensive kind of test.
Somerset County alone (the only part of Maryland for which I have found figures), about 100 acres of farmland have been lost every year for the past decade.
Farmers do have some options. Some grow switchgrass or saltmarsh hay in salted fields, highly salt-tolerant alternative crops for which there is a small market. Others plant the land in salt-tolerant wildflowers for bees and then go into business selling honey. Or a salted field can be allowed to become marsh and then hunted. Putting conservation easements on land that can no longer be farmed can bring real tax benefits, too. But it’s not a good situation. There are families who have farmed the same land for generations for whom that tradition is simply over now.
Saltwater intrusion doesn’t just hurt farmers. There may be indirect economic effects coming down the road, from widespread loss of farmland, and as coastal forests are lost and aquatic species shift to more salt-tolerant communities, familiar landscapes will become less so. These are real losses. They matter.
Saltwater intrusion isn’t the only problem climate change causes on Delmarva–there’s still extreme weather of various kinds to contend with, for example, but saltwater is our particular problem. We simply have more of it than almost anywhere else.
Context, Story, and Hope
Photo by Annie Spratt on Unsplash
Climate communications experts often explain the failure of the climate action message by saying it’s difficult for people to engage with information that is too negative and too far removed from their lives. Well, increasingly climate change is not far away. It’s trees dying. It’s farm yields dropping. It’s the woods where you went hunting with your dad converting to marshland. It’s my in-laws’ river-front house, where there used to be a wide private beach–I’ve seen the old home movies of young people in old-fashioned bathing suits playing there–and now the lawn ends abruptly in a stone bulkhead. Probably everyone on Delmarva, or at least everyone near even brackish water, has such a story, either their own or one told by a friend or neighbor. I’d like to see more of those stories being told. I’d like to see more people realizing what they’re seeing is climate change.
As far as negativity goes, my feeling is it’s not overly negative to scream “fire!” if your building is, in fact, burning. On the contrary, hope begins with action, and action begins with awareness of why one needs to act.
But if the only thing one hears is a warning scream, it can be difficult to know how to act–it can be hard to even be sure action will do any good.
My feeling is that although sea level rise–and hence saltwater intrusion–is unlikely to go away quickly no matter what we do, there is nothing so bad that it can’t get worse–and that means there is nothing so bad we can’t keep it from getting worse. And there are steps we can take, even as ordinary individuals (I’ve written about some of those steps in previous posts) to make the future better.
Speaking from experience, that hopeless, overwhelmed feeling goes away once we pick a course of action and jump on it.
