The Climate in Emergency

A weekly blog on science, news, and ideas related to climate change


Leave a comment

Climate Change and Cancer

Cancer has been on my mind rather more than I’d like, so this week it occurred to me to check out the links between climate change and cancer. I figured there probably would be some. Horsemen of the Apocalypse tend to roam in packs.

It didn’t take me long online to find out that yes, there are links. There’s even a whole chapter on the subject in a report published by the National Institute of Environmental Health Sciences. Except where otherwise noted, this information in this article comes from that chapter.

Climate Change and Cancers

“Cancer” is not a single disease but rather a whole category of diseases. All cancers have some things in common, but causes and effective treatments both vary. It’s even possible to have two different cancers at the same time, in which case the two need to be treated separately, because what works for one won’t necessarily work for the other. So it’s not good enough to ask whether climate change causes or exacerbates “cancer.” We have to look at which (if any) cancers are involved.

We also have to be clear about what we mean by “involved.” I have not found anyone claiming that being too hot, too dry, too wet, or too wind-blown can actually cause any cancer (though these cause plenty of other health problems!), but there are indeed cancers that would be more rare if we weren’t heating the planet.

Some skin cancers are caused by exposure to UV light, and the thinning of the ozone layer caused more exposure. The main ozone-depleting gasses are also greenhouse gasses. Had those gasses not been released, there would be less climate change and less skin cancer. Higher temperatures also tempt people to expose more skin to damaging UV rays.

The other big climate-related cancer is lung cancer, which can be caused by air pollution. Many common air pollutants are also greenhouse gasses. Wood smoke, as in what comes off of all these wildfires we have these days, may also cause lung cancer.

So, it’s official; more climate change means more lung cancer and skin cancer.

A less direct source of risk is that climate change can make it easier for people to contact certain pollutants. For example, floods caused by the more extreme weather we’re getting often sweep up some very serious pollutants. Exposure to floodwater, or drinking water or soil contaminated by floodwater, could therefore involve exposure to various carcinogens. Higher temperatures make some pollutants more volatile, driving them out of soil or water and into the air. When the pollutants in question are carcinogens, that translates into more cancer, or more cancer risk in places that used to be relatively healthy.

Complicating Factors

You knew there would be complicating factors, didn’t you? One source of complication is that there’s a lot we don’t know about what causes various cancers or how the causal connection works. There are a lot of pollutants that might be carcinogenic, but we don’t know, or we know they cause cancer, but not how dosage relates to risk. Will one swim in contaminated flood water do it? We don’t know.

Another major source of complication is that a lot of the processes being advanced to lessen anthropogenic climate change could also carry increased risk of cancer. Nuclear power is one obvious example. Less obvious is that cadmium is used in the manufacture of solar cells, and cadmium is a known carcinogen. Hydrogen fuel cells could pose a problem if the cells leak, since hydrogen is an ozone-thinning gas and thus an indirect skin cancer risk. Even biodiesel could be a threat, since the chemical profile of its exhaust is different than from petrodiesel, and we really don’t know what breathing in that exhaust might do.

It’s not that we’re damned if we do, damned if we don’t–it’s that the picture is complex and we don’t understand it very well, yet.

What we do know is that using less energy from any source is the best bet for reducing anthropogenic climate change without causing secondary problems. But we knew that already. And using less energy isn’t a popular option.

Specific Pros vs. Vague Cons

While cancer is probably not the worst thing that anthropogenic climate change is doing, it’s definitely on the menu. If you have been touched by cancer in some way, you know how awful the malady is. It’s like a war zone breaks out inside your family and no one else can see or hear the bombs going off, the infrastructure breaking. We know, now, that the further anthropogenic climate change goes without somebody doing something about it, the more cancer there will be.

The problem is that not only don’t we know who is going to get cancer, we also have no way of knowing which cancers are climate-change related. That’s what increased risk means. We might know how many more cancer diagnoses there are, but we won’t know which of those people would have gotten cancer anyway. It’s hard to get emotionally involved with a statistic. You can always convince yourself that it applies to somebody else.

Contrast that with the concrete, obvious benefits of using fossil fuel–if you drive to the store for a loaf of bread, you know perfectly well who got that loaf of bread. If you own a petrochemical company, you know perfectly well who made a very comfortable living. You don’t know who got cancer from that same tank of burnt gas.

The same problem occurs with any cost/benefit analysis of fossil fuel use. If we’re going to get ahead of this thing, we’re going to have to make those unpredictable cancer cases seem just as real as that loaf of bread, that comfortable living.

 

 

 

Advertisements


Leave a comment

Tick, Tick, Tick, Tick, Tick

When I was little, the appearance of a tick itself was reason for alarm.

“So-and-so found a tick the other day!” Mom would announce. “Be careful!” I think I had one on me–just one–my entire childhood. I’m not sure whether there were really so few ticks, or if we were simply bad at finding them. I do know that when I moved to Maryland, I didn’t have to be good at finding the little parasites. Huge numbers of them found me.

Seriously, go for a walk in my neighborhood in the summer, and you’re likely to pull off ten or twenty just while you’re walking. When you get back to the house, strip off your clothes and find a dozen more. They won’t have had time to embed, yet, so it’s not a big deal. You just get in the habit of routine regular tick checks.

Incidentally, I don’t find the standard advice of long pants and so forth very useful. Sure, fewer ticks will make it to skin that way, but some will, and they’ll be impossible to find without taking your pants off, which the neighbors tend to frown on. So the ticks get more time in which the crawl into someplace inaccessible and bite.

My advice?

  • Wear as little clothing as possible and then investigate every tickle and itch immediately–it might be a tick.
  • Do a thorough tick check and take a shower immediately upon returning home.
  • If you walk through a tick-hatch and get zillions of the tiny things on you, don’t panic. They can’t give you any diseases because they’re babies and don’t have any diseases yet. Remove them as best you can, stick them on a length of tape so they can’t escape and bite you again, then invest in a large supply of anti-itch cream.
  • Don’t bother learning to identify different species of tick. They can all give you SOMETHING, so just avoid getting bitten by any of them, and if you get sick, go see your doctor.
  • Look up the proper way to remove an embedded tick. NEVER put anything on the tick to make it let go, because that makes the tick vomit into you first and then you’ll definitely have whatever it was was carrying.

I’m not a doctor, this is just my personal approach to the problem.

The reason I bring all this up is to make clear I am personally familiar with the density of the tick population in the mid-Atlantic region of the United States, and I am equally aware that New England has fewer of them. Don’t get me wrong, New England does have ticks–Lyme disease is named after a town in Connecticut, after all–but the problem is simply not on the same scale.

That could be changing.

There are reasons other than climate change. Tick population dynamics and the epidemiology of tick-borne illnesses are complex, inter-related topics with a lot of variables. For example, modern land-use practices, which has converted vast areas of the United States into mosaics of tiny forested patches with houses mixed in, favors white-footed mice, which are the primary hosts of deer ticks–which transmit Lyme disease. The mice, after all, can use tiny habitat patches (and houses) just fine, but their predators can’t. No foxes, no bobcats, no black snakes, no owls, etc., all adds up to oodles of mice and oodles of ticks. So, some kinds of ticks would be a bigger problem than they used to be, even without climate change.

But yes, the climate is helping.

The story is a complex one, because not only do factors other than climate influence tick populations, but the response of ticks to climate is not straight-forward. For example, ticks of the same species may become active at different temperatures in different parts of their range. All these different variables working together mean that predictions of what climate change will do to different species of ticks can disagree with each other widely. But some increases in tick-borne illnesses have been traced to climate change–so we don’t know what’s going to happen in the future, but in the present, the ticks are worse in some places already because of climate.

For example, the two species responsible for infecting people I actually know, deer ticks and lone star ticks, are both expanding their range because of climate change. Both can transmit multiple illnesses. Lone stars, named for the white spot on their backs, can give you a (possibly life-long) allergy to red meat. Without giving away any individual’s medical history, I can say I’ve seen this one, it’s quite real. And lone stars are now in all New England states, though they didn’t used to be.

(By the way, the article that I’ve linked to above describes lone stars as “hunting in packs.” I’ve seen the behavior the article is describing, and the phrase is misleading. The ticks aren’t acting cooperatively, like mini-wolves. But, unlike deer ticks, they can and do walk towards potential hosts. In my neighborhood, population densities are often high enough that half a dozen might be near enough to notice the same person, and if you stay still for a few minutes they’ll converge on you. They’re easy to avoid or remove, but it’s creepy to watch.)

And then there’s the winter ticks, which have always been in New England, but warming climates are letting their numbers surge so high that they’re literally bleeding moose calves to death.

All of which is to say that if you head north in the summer, as we do, and you notice more ticks on yourself and your pets than you used to, as we have, it’s not your imagination.


Leave a comment

A Break for Puffins

“How’ve you been liking the hot weather?”

I turn around and spot the man sitting on the rock at the edge of the parking lot. He works at the restaurant across the way and he comes here to take his smoke breaks. We say hi to each other every time he does. He’s one of those strangers who’s almost a friend.

“I don’t like it, much,” I say, of the weather. I’ve been either under- or over-dressed all day.

“Yeah, it’s funny,” he says, “yesterday it was warm in Bar Harbor, but cold here. Today, it’s hot here, but it’ll be cold in Bar Harbor.”

Bar Harbor, I should add, is not that far away, yet he could be right. I’ve known it to rain in town but stay dry just three miles away.

“You know, I’ve heard the Gulf of Maine is 11 degrees warmer this year than normal?”

“Yeah, I know,” he tells me.

“It’ll be a bad year for puffins,” I add.

“Oh?”

“Yeah, when the warm water comes in, so do warm-water fish, which are a little bigger and rounder. The adult puffins can catch the warm-water fish just fine, but the chicks can’t swallow them. So, in years when warm-water fish species predominate in the Gulf, every puffin chick in Maine starves to death.”

“That’s really sad.”

“Yeah, it is.”

“That’s really sad.” He seems to really feel for these puffin chicks. “But there’s nothing anyone can do about it.”

“Well, stop global warming.”

“Yeah, but we can’t do that,” he protests.

“Yes, we can,” I counter. “Not immediately, because of atmospheric lag, but you know, nothing is so bad that it can’t get worse? By the same token, nothing is so bad that we can’t keep it from getting worse.”

“Yeah. I like puffins. I have paintings of puffins hanging in my bathroom. I tell people, these are real birds. They’re not made-up! I’ve only ever seen a couple of them.”

“I’ve never seen even one,” I admit. “Where did you see them?”

“It was last year. They took us on a cruise—among the islands.”

“Neat.”

“Yeah. You know, I’ve seen another Maine bird? I can’t remember what it’s called, but I can remember the sound it made, at night, in the water….It sounded like a frog, you know—a, a, bullfrog? Where I’m from, we have another frog that makes weird sounds, it’s called something else. It sounded like a frog, but my friend said, no, that’s a bird.”

“Can you imitate the sound?”

“No, but I can hear it in my head. I saw it, and it was a bird. It was dark, and sort of duck-like….”

“A loon?”

“Yes! That’s it! A loon!”

“They winter with us, in Maryland,”I told him. “They’re here in the summer and with us for the winter. They do make lots of sounds.”

“Cool! Well, I gotta go. It’s been nice talking to you.”

“Nice talking to you,” I tell him, and mean it, and I watch him head back into the restaurant through the back door.


Leave a comment

How Quickly Can We Cool?

I could write about lots of horrible things going on in the news this week. Unfortunately, I suspect there will be plenty of horrible news item to write about next week. This week I want to write about global cooling instead.

I’m working on a book set after the end of the age of fossil fuel, which means I need to understand how the climate responds to a falling carbon dioxide level. Obviously, average temperatures would fall, but how quickly? Warming has a lag time of several decades, because it takes time for heat to build up. Logically, cooling should be much faster. In bed, add an extra blanket and you won’t warm up for a few minutes, but kick your blankets off and you’ll cool down right away. But faster and instant are not the same thing, so how long would global cooling take? Since I need to read up on the issue anyway, I figured I’d share my results with you.

My fictional scenario is that a pandemic triggers the end of civilization, the total end of fossil fuel use, and a 90% reduction of the human population. It’s a complex and complicated scenario, because while most carbon dioxide emissions end, some types of methane emissions, such as leaking well-heads or outgassing landfills, would continue or even increase–and methane is a more powerful greenhouse gas than CO2 is. Would a net increase or decrease in climate-forcing power result? A smaller human population would allow widespread reforestation, but the warming that has already occurred would continue to cause forest dieback in some areas. Would there be a net increase or decrease in forest biomass?

Also, the planet would continue adjusting to the greenhouse gas and the heat that is already present. If greenhouse gas levels stabilized where they are now, temperatures would continue to rise for several decades. And even if the planetary temperature stabilized where it is now anyway, glaciers and permafrost would continue to melt. Melting permafrost, remember, releases methane, so the greenhouse gas concentration might continue to rise. Potential feedback loops abound.

I would love to stick all these variables into some giant computer and run a full simulation, but I don’t have that option. The best I can reasonably hope for is a definitive answer to just one question; assuming the greenhouse gas levels do fall, how long until temperatures start falling also?

Unfortunately, since the chance of my scenario occurring any time soon is very small, nobody seems to be studying what a falling greenhouse gas level would look like.

Fortunately, a version of my scenario did happen about five hundred years ago, when diseases killed off 90% of the population of the Americas, allowing widespread reforestation and causing the second, deeper phase of the Little Ice Age. So, how fast did that happen?

According to one estimate, the reforestation of the Americas could have removed anywhere from two to 17 billion tons of carbon dioxide from the atmosphere. That’s somewhere between 10 and 50% of the CO2 reduction recorded in ice core samples from Antarctica, so something else was going on also. There are various possibilities. But carbon dioxide levels do tend to track known European and Asian pandemics, which also allowed reforestation. The first, less severe phase of the Little Ice Age, may have been, in part, related to reforestation after the Black Death.

So, let’s look at the timeline–since researchers at Stanford University must think the timing of the second phase of the cold period is consistent with it being influenced by the American reforestation. Does the timeline suggest a lag exists?

The second phase of the Little Ice Age began around 1600 and lasted until around 1800. The drop in carbon dioxide, as recorded by Antarctic ice cores, that includes the result of American reforestation began in 1525 and lasted until the 1600s. The first smallpox pandemic in what is now Mexico began in 1519. I can’t confirm that was the first of the American contact pandemics, but Europeans handn’t set foot on the mainland much before that, so it must be close to the beginning.

So,

1519: people in the Americas start dying of exotic diseases to which they have no natural immunity.

1525: global carbon dioxide levels dropped by six to 10 parts per million and stayed that way for over 75 years.

1600: temperatures drop globally, though the drop may be most severe in the northern hemisphere and stays that way for two hundred years.

There is a lot about the Little Ice Age that is debatable–why is started, why it stopped, how severe it was, all of that. That significant reforestation could follow the beginning of the pandemic by only six years itself seems questionable. However, regardless of why the carbon dioxide drop occurred, it was followed by a drop in temperature 75 years later. Carbon dioxide levels rose again shortly thereafter. Temperatures rose again about 100 years after carbon dioxide levels–that delay on warming is consistent with the principle of atmospheric lag.

Richard Nevle and his colleagues at Stanford believe that a 75 year delay in cooling is not too much for a causal relationship to exist. So there is a significant lag on cooling also.

In our modern situation, carbon re-sequestration is unlikely to be rapid–even in the best case scenario, reforestation cannot absorb more than a fraction of what burning fossil fuel released. The rest must be accomplished by peat accumulation and slow absorption by ocean water. And whatever drop in carbon levels occurs, whenever it occurs, a human lifetime could pass before the temperature follows.

We’ve got to get started.

 


Leave a comment

Nor’easters

Last week, I spent three days huddled inside because of high winds rattling the house and ripping dead branches off of swaying trees–and I live in Maryland, where the storm (“Winter Storm Riley,” officially) was relatively minor. What we saw was nothing, compared to what the people in coastal Massachusetts experienced.

Now we’re preparing for another one (“Quinn”). And some meteorologists expect another storm after that.

What Are Nor’easters?

This week’s storms are nor’easters. They’re not unusual, although the recent one was an extreme example. Like hurricanes, they are very large low pressure systems that bring wind and rain (or snow) and last for several days. Unlike hurricanes, they draw their power, not from warm water (there wasn’t any under Riley) but from the interaction between warm and cold air masses. They generally form in winter. In the case of Riley, a storm system moved east across the US, then drove the rapid development of a very intense low pressure area just off the coast, which then moved north and gradually east. On satellite images, the thing looks like a hurricane, a massive pinwheel of swirling cloud off the coast. While too far out in the Atlantic now to influence my weather directly, Riley still exists. It’s busy causing damaging surf on Puerto Rico from thousands of miles away.

Nor’easters seldom approach hurricane force winds. Typically, these storms are gusty, not windy, a serious inconvenience, but not a danger, unless you have bad luck (such as an unusually weak tree limb right above your car). Rily was the most intense I’ve seen, and around here it was only in the high tropical storm-force range.

The lesser winds do not make these storms mild.

For one thing, nor’easters have much larger peak wind fields than hurricanes do. While a hurricane might have sustained winds of 90 miles an hour near its center, most of the area the storm passes over will get much weaker winds, say 50 or 60 miles per hour. A strong nor’easter will blast the same 50 or 60 miles per hour over the same large area, it just lacks the 90 mph core.

Second, wind is not the most destructive aspect of a hurricane, it’s just the easiest way to compare storms to each other. The size of the wind field, the speed the storm travels (and hence how long it spends in any one place), the size of its storm surge, and how much it rains are all much more important in terms of its destructive power–and above all, there is the question of what it hits. A low-lying, heavily populated area where the people lack both money and political power is where the disaster happens. And nor’easters have large wind-fields, heavy precipitation, sometimes heavy coastal flooding, and can persist for days.

And, as with hurricanes, when we get a bad one (or several) people start asking about climate change.

Nor’easters and Climate Change

Meteorologists can be quick to point out that individual storms can’t be linked to climate change, which both is and is not true. One recently referred to efforts to draw the link as “witch-craft.” That’s at best disingenuous.

We can absolutely prove that climate change is making nor’easters worse, for the same reason that climate change is making hurricanes worse. First, the single most dangerous aspect of either storm is coastal flooding, which is unquestionably worse now that the sea level is several inches higher than it was when most existing infrastructure was built and when the data used to define flood zones for insurance purposes were gathered. The apparent sea-level rise varies from place to place, because geological forces are also in play making the ground rise in some places and fall in others, but climate change can claim about eight inches of it world wide, due to a combination of thermal expansion (things, including oceans, expand when they heat up) and glacier melt. That means every coastal flood event, including all hurricanes and all nor’easters, are  eight inches worse than they would otherwise have been.

Eight inches doesn’t sound like much, until you imagine them inside your living room.

Also, a warmer planet means more humid air, which means wetter storms. In the winter, as long as the air temperature is below freezing (which isn’t really very cold), that means more snow–more closed roads, more fallen trees and snapped power lines, more collapsed roofs, more car accidents, more missed days of school. All of this should sound very familiar to some readers right about now. All that white stuff? Yup, it’s a symptom of climate change, not a negation of it. In warmer weather, wet storms means rain which means flooding. That’s ruined houses, damaged roads, washed-out bridges, soaked earth–leading to toppled trees and snapped power lines–and drownings.

We’ve been through this already with hurricanes; climate change does not have to cause individual storms, or even make a certain type of storm more likely or more intense, in order to directly cause more storm damage.

But can climate change cause nor’easters? Yeah, it kind of looks like they can.

Connecting the Dots

To tell this story, we have to cover a bit of atmospheric anatomy.

Remember the polar vortex? It was all over the news a few years ago, but I haven’t heard of it of late. It still exists, though. Actually, there’s two of them. Or sometimes three.

The polar vortex is not a type of storm, but rather either of two long-term atmospheric features–this sounds a little different than the last time I explained it, because the two features tend to get mixed up in public discussion, and I only recently learned that they are distinct.

Originally, “polar vortex” meant a circular pattern of winds that forms in the stratosphere around the pole in winter. It’s also called the polar night jet, because the sun does not rise in the winter at its latitude. The winds blow from west to east and divide cold polar air from warmer air at lower latitudes–the stratosphere is a layer that begins several miles up, above where weather happens. But in recent years, the term has also been applied to the jet stream, a circular pattern of winds in the troposphere–a much lower layer–also at a boundary between warm and cold air, but much farther south. The jet stream meanders, across the latitudes covered by the United States and southern Canada. The jet stream exists winter or summer, and its shape and location help determine whether any given area gets warm, tropical air or cold, arctic air this particular week.

Ok, so, definitions taken care of, what does either polar vortex have to do with climate change or Winter Storm Riley?

A lot of the strange weather we’ve had in recent years has been caused by extreme waviness in the jet stream. Because the jet marks the boundary between warm air and cold air, an extreme meander means that warm air flows much farther north than normal over here, while cold air flows much farther south than normal over there. At the same time, weather systems tend to persist longer and move slower than normal. Rainy weather becomes catastrophic floods. Dry, hot weather becomes killer heat waves and droughts. The extra waviness is likely caused by global warming, especially the loss of Arctic sea ice. As the planet warms, the polar regions warm faster than the rest of the planet, decreasing the contrast between the warm and cold regions and weakening the jet stream that lies at their boundary. Weak jets are slow and wavy.

So climate change doesn’t cause snowstorms in Florida by some magical method of “global weirding,” but instead through a fairly straight-forward form of atmospheric messiness, a weakened and wobbly boundary between warm and cold caused directly by the warming Arctic.

The next bit is less certain, as in not all scientists agree, but a weak and waving jet stream could be one of the mechanisms able to put pressure on the polar vortex and cause it to temporarily break down and allow warm air in over the pole. Such an event is, sensibly enough, called a Sudden Stratospheric Warming, or SSW. Although the stratosphere itself doesn’t have weather in the normal sense of the word, it can influence the weather of the troposphere, resulting in odd weather several weeks later–such as cold snaps, warm periods, or violent storms. SSWs appear to be natural (we have only been measuring stratospheric temperatures for a few decades, now, so it is hard to be sure), and their frequency has not increased, but some computer models suggest an increase could happen, and the extra-wavy jet stream could make it happen–or could already be making it happen. It takes a while to gather enough data to document a change in events that don’t happen every year.

Riley (and presumably its sibling-storms, to some extent) was triggered by a particularly severe SSW, one which ripped the polar vortex in two and triggered a bizarre winter heat wave in which parts of the Arctic rose above freezing for days on end. There’s no sun up there, remember, yet the ice started melting instead of growing–a bad sign. That triggering is not in doubt. And the SSW could have been triggered by a weak and wavy jet stream, which is itself caused by melting sea ice (notice the ominous cycle implied there?). Melting sea ice is, rather unambiguously, a symptom of global warming.

That “maybe” in the middle of the causal chain remains, but this is very close to a linkage between climate change and a single storm. Anyone who claims differently is going to have to marshal a much better argument than claiming “witchcraft” to convince me otherwise.

 


Leave a comment

Dead Zones?

In previous years I have written New Years’ retrospectives, recapping notable climate-related news stories from over the past twelve months.

This year, a retrospective of the past few weeks might be in order.

While I’ve been occupied writing holiday posts–for Yule, for Christmas, for New Years’ Day–and generally being distracted by family obligations, we’ve seen California’s worst wildfire ever (followed by a deadly mudslide just today, which is not unrelated), a rather startling case of Extreme Winter, and a new and really frightening report on marine dead zones. And there have been various political issues. Let’s pick one of these stories and catch ourselves up, shall we?

Please note that where I make statements of fact without linking to a source, it’s because I’m using a source I already linked to.

Dead Zone

The term, “dead zone” is, unfortunately, not a metaphor. These are areas, usually along the coast, but sometimes out at sea, where there is so little oxygen in the water that animals can’t live. It’s a horrifying idea. Imagine minding your own business, living as you usually do, and all of a sudden breathing does no good. Dead zones aren’t spontaneous. They are caused when flushes of nutrients (usually runoff from over-fertilized farm fields or lawns, or from sewage treatment plants) trigger massive algae blooms in the water. Although algae itself make oxygen, when the supply of fertilizer is exhausted, the algae die off and decompose and bacteria go through a population explosion. While not all bacteria breathe oxygen, these do, and there are so many of them that they use up the local supply, causing a dead zone.

In some circumstances, a dead zone can also be caused by algae directly, since algae, too, must breathe (I mean “breathe” loosely here, since all this happens under water)–it is a misconception that plant breathing is the reverse of animal breathing, that plants breathe in carbon dioxide and breathe out oxygen. Instead, plants breathe in oxygen just as we do, and for the same reason–to “burn” sugars for energy. The difference is that we get our sugars by eating, whereas plants make sugars by photosynthesis. Free oxygen is a byproduct of photosynthesis, and fortunately for us, plants make more of it than they need. But in warm, shallow water, a super-abundance of algae can sometimes run short of oxygen at night, when of course photosynthesis stops but breathing doesn’t. In Mobile Bay, in the summer, if the wind and tide are just right, this type of dead zone can move towards the shore, driving anything capable of fleeing before it. Long about dawn, anyone on the right stretch of shoreline can scoop up as much seafood as they want. Before the reason for this influx was discovered, it seemed like magic, an unearned gift from the sea. It’s called the jubilee.

Jubilees occur, less predictably, in other areas, too, such as the Chesapeake Bay, anywhere a dead zone can develop and then move towards shore. The size, shape, and duration of a dead zone depends on many factors, including, temperature, salinity, and wind direction. Dead zones are often low-down in the water column, leaving oxygenated water near the surface, which is why jubilees involve bottom-dwelling species, such as flounder or crab.

Dead zones occur in certain areas every summer, but their shape and size vary from year to year. Evidence of dead zones has been found in sediments going back at least to the late 1800’s, but the same study shows a worsening of the problem since 1950. It may be possible for a dead zone to form without human help, but humans unquestionably cause most of them.

In any case, the problem is less that individual animals die in the short-term, and more an issue of habitat loss. Because of dead zones, the places where marine life can exist are now smaller.

It’s worth noting that there are parts of the ocean where very little lives, and very little has ever lived because there is not much in the way of nutrients for various reasons. These are not dead zones. By definition, a dead zone is a place where life would occur if something had not used up so much of the oxygen.

Ok, Where Does Climate Change Come In?

Dead zones are mostly a story about pollution and land use–the factors that send excess nutrients downstream and into the sea. As such, the problem is sort of a cousin to climate change; the two have causes in common. But climate change also has a direct influence, most obviously because the warmer the water is, the less oxygen it can carry–and the less oxygen must be used up before a dead zone occurs. Also, warmer water raises the metabolisms of the animals that live in it, meaning that they need more oxygen, using the precious stuff up faster–and possibly also making dead zones occur at higher oxygen saturation levels.

Also, remember that salinity and wind direction are also factors in dead zones–and climate change can alter both.

The mechanisms here are a little complex, and I’m not going to describe all of them. Fresher water is lighter than saltier water, which means the two tend to resist mixing. River water flowing into the Chesapeake Bay, for example, or raining onto it, tends to float on top of saltwater flowing in  from the ocean. This resistance to mixing is not absolute–the surface waters of the Bay get brackish pretty quickly–but it is enough that the water on the bottom has trouble getting oxygen from the air. If the algae and sea grass in the water can’t produce enough of their own oxygen, a dead zone develops. The salty water is effectively under an air-tight lid, unless wind blows and stirs the layers.

Well, as sea level rises, more saltwater flows into the Bay. As the deeper waters get saltier, the resistance to mixing gets stronger, and dead zones get more likely.

In fact, although the dead zones of the Chesapeake Bay are now shrinking (thanks to concerted efforts in the Chesapeake watershed to limit nutrient run off), the amount of excess nutrient in the Bay water is shrinking faster. That is, the Bay has been dying more easily now than it used to, and the problem is getting worse. No one is exactly sure why, and various feedback loops and long-term ecological changes  (water dies easier if it’s been sick for a while?) could be in play, but sea level rise could be part of the answer, as could rising temperatures. Changes in wind direction may also play a role, as winds from the south have become less common since the early 1980’s, in favor of winds from the west. Since the Chesapeake is large, north to south, and skinny east to west, the change in wind direction has meant less wave action, and thus less mixing in Bay waters. I don’t know that the change in wind direction has anything to do with climate change–but I don’t know that it doesn’t, either.

As often happens, there are other factors that could be involved, some of which could actually mean climate change reduces the size of dead zones, long term. No one knows for sure.

But so far, as climate change progresses, dead zones have been getting worse. I suppose that could be a coincidence….

What’s the Story?

The reason I’m bringing all of this up now is that a study has just come out showing that although the Chesapeake dead zones are shrinking, dead zones elsewhere are getting much worse–and dead zones are even occurring and worsening in the open ocean, which is generally much more resilient.

Each area’s dead zone has its own history and its own context. How long has the zone been occurring, which industries cause it, who gets hurt by it, what is the relative political power of each, what details of local geography and ecology make the situation worse or better, what stresses other than low oxygen levels might be bothering marine life…. I’m reluctant to make generalized statements without first looking into the rabbit hole of information on each zone. Climate change may be a factor in some zones but not others.

But these zones are worth watching. Is there one near you? Does something you do, or don’t do, help cause a dead zone down stream? Are your state, local, and Federal representatives aware of the problem and concerned about it?

There are zones in the water that kill fish and many of them are growing.

 

 


Leave a comment

Speak No Ill of the Dead

I’m re-posting this one from last year, with minor edits. I have not found any new species to add to the list, though unfortunately that doesn’t mean there aren’t more that belong on it. There is a leak in the world and life is running out of it…

Today was Hallowe’en, of course. A rollicking, morbid carnival, a celebration of the mortal flesh through sugar, alcohol, sex, and fake blood (if you don’t believe me about the sex, look at the women’s costumes available in stores), a blurring of identity and the thrill of things that go bump in the night.

I could write about the impact of the holiday on global warming, but that’s been done. I could write a scary story about our possible future, but that’s been done, too.

But, basically, I’m not all that interested in Hallowe’en anymore. I’ve grown out of trick-or-treat and I’m not frightened by blood, fake or otherwise. I’m more interested in the older traditions of taking a day to honor and remember the dead. This is therefore a Day of the Dead post, a Samhain post. I want to mark and honor the dead of climate change–not as a scare tactic or a self-flagellation of guilt, but simply as an act of witness. Because it is the right thing to do.

There are several possible ways to go with this. I could focus on individuals who have died of climate change, but linking global warming to particular deaths is very difficult. The result would also be too similar to my recent post comparing the mortality rates of climate change and Ebola. Instead, I want to honor whole species that have died. I’ve often thought that reading a list of recently extinct species names, the way the names of individuals lost to some accident or disaster are sometimes read, would be a powerful way to add an ecological dimension to Samhain. I’ve never done it, in part because finding such a list is difficult. Compiling a list of the extinct is hard, since we don’t always know a species exists before it stops existing again, and because it’s hard to be sure a whole species is really gone and not holding on in some remnant population somewhere. What lists exist seldom turn up whole on Internet searches, perhaps because many of the species on the list are plants and animals most people have never heard of.

Still, I intend to observe the Day of the Dead by formally noticing our planetary losses.

Looking for Smoking Guns

Which species, if any, have gone extinct because of climate change is a bit complicated.  I addressed the question in some depth in an earlier post, but it comes down to the difference between ultimate cause and proximate cause; if you fall off a cliff, the ultimate cause of your death is your poor footing, while the proximate cause is your impact with the ground. The problem is that the connection between those two causes is rarely as obvious or straight-forward as in that example.

Climate change as the ultimate cause of extinction might be linked with any number of proximate causes. Some of them are: drought; habitat loss (think polar bears and sea ice); the extinction or relocation of an ecological partner; and new competitors, pests, or diseases that take advantage of warmer weather. Of course, most of these problems can have other ultimate causes as well. Climate change is not likely to be the species’ only major problem–consider the paper birch, which is dying out in parts of New England because of a combination of exotic diseases, climate change, and probably the advanced age of the relevant stands (the species requires bare soil to sprout, such as after a fire or logging, and there happened to be a lot of that in New England decades–hence, a lot of aging birches). Against this complex backdrop, it is hard to say for certain which extinctions actually belong at global warming’s door.

Some years ago, scientists announced the extinction of the Seychelles snail, the first species known to go extinct because of climate change. Fortunately, a previously unknown population of the snail turned up recently–it’s not extinct at all (though presumably still in grave danger). Many writers have treated the snail’s resurrection as some kind of embarrassing “oops” for climate scientists, which of course it is not; the species took a huge hit because of global warming, and the fact that it’s still hanging on is great news. Confirming an extinction is very, very hard–a bit like looking for the absence of a needle in a haystack. Mistakes are inevitable, and welcome.

The golden frog and the Monteverde harlequin frog are sometimes cited as victims of climate change as well. The proximate causes of the golden frog’s demise were habitat loss due to drought and also the chytrid fungus, which could be exacerbated by climate change. Chytrid has extinguished or gravely endangered many other amphibians world-wide, so at least some of them might be considered victims of climate change as well–as could various non-amphibians, including some no one knows about yet.

But there is another way to look at all of this.

Climate change itself has a cause, and that cause has other effects. As I explained in another previous post, our burning fossil fuel has destabilized the biosphere as a whole by altering how energy flows through the system. Climate change is one consequence of that destabilization, but systemic biodiversity loss is another. That is, no matter what the proximate cause of an extinction is (whether climate itself is directly involved), the ultimate cause of this entire mass-extinction event is fossil fuel use.

We know what to do about it. You know what to do about it. If you’re an American citizen, VOTING is a major and necessary step. But this is the festival to honor the dead, and we should take a moment to do that–to remember that these are not just numbers, political statements, arguments, but actual animals and plants, whole ways of being, that will never exist again.

I did find a list of historical extinctions. You can look up the whole thing here. It is far from comprehensive, but even so it’s still too long for me to copy over all of it. I’ll just focus on those from the list that have been lost since my birth.

Pinta Island Tortoise

Chelonoidis abingdoni

Last seen, 24 June 2012

Vietnamese Rhinoceros

Rhinoceros sondaicus annamiticus

Last seen, 29 April 2010

Christmas Island Pipistrelle

(a bat)

Pipistrellus murrayi

Last seen, 27 August 2009

Chinese Paddlefish

Psephurus gladius 

Last seen, 8 January 2007

Yangtze River Dolphin

Lipotes vexillifer 

Last seen, before 2006

Po’o-uli

(a bird in Hawaii)

Melamprosops phaeosoma

Last seen, 28 November 2004

Saint Helena Olive

Nesiota elliptica

Last seen, December 2003

Vine Raiatea Tree Snail

Partula labrusca 

Last seen, 2002

Pyrenean Ibex

Capra pyrenaica pyrenaica 

Last seen, 6 January 2000

Sri Lanka Legume Tree

Crudia zeylanica

Last seen, 1998

Nukupuu

(a bird in Hawaii)

Hemignathus lucidus

Last seen, 1998

Western Black Rhinoceros

Diceros bicornis longipes

Last seen, 1997

Aldabra Banded Snail

Rhachistia aldabrae

Last seen, 1997

Zanzibar Leopard

Panthera pardus adersi

Last seen, 1996

Swollen Raiatea Tree Snail

Partula turgida

Last seen, 1 January 1996

Golden Toad

Incilius periglenes

Last seen, 1989

Antitlan Grebe

Podilymbus gigas

Last seen, 1986

Alaotra Grebe

Tachybaptus rufolavatus

Last seen, September 1985

Eungella Gastric-brooding Frog

Rheobatrachus vitellinus

Last seen, March 1985

Kaua’i ‘O’o

(a bird in Hawaii)

Moho braccatus

Last seen, 1985

Christmas Island Shrew

Crocidura trichura

Last seen, 1985

Ua Pou Monarch

(a bird in Polynesia)

Pomarea mira

Last seen, 1985

Amistad Gambusia

(a fish, in Texas, USA)

Gambusia amistadensis

Last seen, 1984

Conondale Gastric-brooding Frog

Rheobatrachus silus

Last seen, November 1983

San Marcos Gambusia

(a fish, in Texas, USA)

Gambusia georgei

Last seen, 1983

Kama’o

(a bird in Hawaii)

Myadestes myadestinus

Last seen, 1983

Guam Flycatcher

(a bird in Guam)

Myiagra freycinet

Last seen, 1983

Aldabra Warbler

Nesillas aldabrana

Last seen, 1983

Galapagos Damselfish

Azurina eupalama

Last seen, 1982

Marianas Mallard

Anas oustaleti

Last seen, September 1981

Southern Day Frog

Taudactylus diurnus

Last seen, 1979

White-eyed River Martin

(a bird in Thailand)

Eurychelidon serintarea

Last seen, 1978

Little Hutia

(a rodent in Honduras)

Mesocapromys minimus

Last seen, 1978