The Climate in Emergency

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


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.

 

 

Advertisements


Leave a comment

Many Waters Cannot Quench

I was going to write something to do with my fortieth birthday, which has just occurred, and offers various possibilities for potentially interesting riffs on life. I had some ideas. But then Hurricane Harvey got in the way, as hurricanes tend to do.

To be clear, I am not personally being impacted by Harvey, I’m in a different part of the country, but I have friends in Texas and I’m thinking of them. And, when any form of weather produces “catastrophic” damage (the term being used by the experts), I really cannot ignore it.

Voices in the Dark

Social media is an odd but effective way to watch an unfolding disaster. Not that it can replace journalism, we do need fact-checking, context, analysis, etc., but the unfiltered voices of the multitudes add an immediacy that the news alone cannot match.

I’m a visual thinker, and when information comes to me in a non-visual format, such as radio or text, I often visualize darkness. Thus, my experience of Superstorm Sandy, aside from its brush through my own neighborhood (racing the storm home in the middle of the night, wind starting to buffet the trailer at three AM on a deserted highway in Delaware) was of voices crying in the dark, on Twitter. The one begging for a generator to keep her ventilator going, somewhere in New York, still haunts me. Did she live the night? I don’t know.

This time the voice in the dark has been a self-appointed citizen journalist, my friend, Bridgette Mongeon. I quote excerpts from her throughout this article with her permission.

Dear friends and family,
Thank you for your prayers during this approaching storm. The rain fall that is expected in Houston and all along the Texas coast is astronomical. I have lived in this home through Ike 2008, Allison in 2001, and our first year we moved in was Alicia 1983. Allison, was a tropical storm that played havoc in our area. Allison was just before 9/11 and was a double whammy on our psyche that I still feel rise up in my belly. Somehow the two are connected and re-stimulating.

I do not know what to expect for my immediate neighborhood. This area has had a tremendous influx of new building and I have no idea what that means for the flow of that much water. I am not evacuating . So many have to evacuate from the south. We have been asked to keep off the roads. I also need to keep an eye on the studio as well as my home…. Harvey is stalling and picking up intensity, which means it could hit land as a cat 4. If people in Houston expected a cat 4 or 5 we all would have been boarding up the windows…. Either way, we are on the east side of the hurricane, which we in the south call, “the dirty side” This, as it sounds, is not favorable…. Prayers go to all the people south of us and along the coast. They are evacuating quite a few people today. Evacuations can often be a challenge and dangerous events because of the amount of people. It is their safety that is priority right now.

Be safe Texans. Thanks for your prayers and well wishes everyone else. I’ll update when and if I can.

August 25, 8:13 AM

Since then, she has been posting regular updates for both local residents (tornado warnings, notices of shelter openings) and people farther afield (a detailed description of drainage patterns in the Greater Houston Area). She still has electricity, internet, and news. Not everybody in her area do, and some evidently have internet but not much else, so she’s acting as an information hub. Even the official journalists are being impaired by the storm–one of her local TV stations has flooded and is off the air. She can hear tornadoes, spun off by the hurricane. She reports that reservoirs upstream are being opened, worsening the flooding, yes, but the alternative is a dam breach, which would be worse. She says she’s ok. Her house is not flooding, though those of some of her neighbors are. She posts cell phone video and drone video from friends showing expanses of fast, brown water.

For my non-Houston friends- to help you understand the devastation:
Houston is huge. The greater metropolitan area is circled by the Grand Parkway – which is 170 miles long. That makes the area of the circle inside the Grand Parkway over 2200 sq. miles.
2200 square miles of densely habited, urban and suburban, areas is flooded.
Imagine if the entire state of Delaware, with twice the population of Manhattan, was under water.
That’s Houston.
It’s still raining.

August 27, 10:42 PM

Reporting from Houston, Tx-The love between neighbors here is stronger than the rain, no matter what race, faith, or political party #Harvey

August 28th, 1:00 PM

A few minutes ago, I learned that of those reservoirs–the ones that began releasing water to avoid an uncontrolled flood–one has been over-topped anyway. The other may soon follow. The Houston area has received over half its typical yearly allotment of rain in the past four days alone.

The storm is heading back out to sea, where it will strengthen, before making landfall a second time, probably in Louisiana. But it’s also possible it could hit Houston twice.

An Unprecedented Storm

As is often true of big disasters, this one owes itself to multiple factors. One, obviously, is the storm itself is unusual. Not only did Harvey grow very quickly into a very powerful storm (Category 4), it then stalled right over Houston for several days, dropping all of its water in the same place, rather than over an extended track, as most storms do. This is not the first time a storm has done such a thing, but the amount of rain is literally without historical precedent. The National Weather Service frankly admitted it has no idea what the impacts are going to be and has even had to create new colors for its weather maps in order to represent the scale of this storm. This returning to sea for more energy thing is also highly unusual.

The other part of the problem–and here I’m drawing on information from Bridgette–is that Houston is prone to flooding anyway. The soil is clay-based and does not drain well, and a development boom has dramatically worsened matters by paving over a lot of ground. There is no way for most of that water to go anywhere, except by flowing down streets and through buildings. Flooding is common in parts of the city even in ordinary rainstorms. For an extraordinary rainstorm to occur here cannot help but have catastrophic results.

What the long-term results will be are not clear, yet. An online search for “economic impact of Harvey” yields varied results–that recovery will take years, that it will be quick, that economic impacts will be large and widespread, that they will be minimal. No one really knows. The storm isn’t even over.

But two facts are worth noting.

One is that Bridgette is right; Houston, with the assistance of the rest of the nation (and even other countries–reportedly, Mexico is mobilizing to help, as it did following Katrina) is stronger than Harvey, and will survive. One of the advantages of being a very rich nation is that we can sustain billions of dollars of damage and simply pay for it. There may be bureaucratic or political hang-ups, we don’t know yet, and the physical acts of clean-up and rebuilding will take time, but we can do this.

The other thing to keep in mind, though, is that we’re not just looking at paying for clean-up and repair. Houston is the fifth-largest economy in the US, and it’s taking the better part of a week off. Zero output. None. Bad news. Houston is also the home of much of American oil refining. Right now, some refineries are closed because workers can’t drive in to work, there is no damage (or hadn’t been, as of yesterday evening) but that could change. There are other Houston-based businesses taking a hit, too, such as Sysco, the company that produces supplies for virtually every restaurant you’ve ever set foot in (seriously, look at restaurant water pitchers–they’re all exactly the same because they come from the same place). The United States as a whole is not in danger, we will get through this, but Harvey is not a local problem. It’s national, possibly global.

The one thing the flooding in Houston is not is the fault of local officials for not evacuating everybody. Bridgette, again:

We have learned from the many storms that there is a way to evacuate. The process is that the lower lying areas or those that are first in harm’s way must be the priority. If everyone from Houston got on the freeways and evacuated, then those in real trouble could not get out. An example was the horrific Hurrican Rita evacuation in 2005. Rita was just weeks after Katrina. And Rita was going to be stronger than Katrina. We were all a little shell shocked down here. During Hurricane Rita, people panicked and according to Wiki “An estimated 2.5 – 3.7 million people fled before Rita’s landfall, making it one of the largest evacuations in United States’ history.”

I was here. I stayed. Here is what happened. It was wall to wall cars. No one could move. It was hot, and gas ran out in the cars on the road. No one could get gas in to help the stranded. I fielded phone calls from friends who were caught in traffic for hours. Many finally turned around, but that was impossible because the city then opened the southbound to go north. It was excruciatingly hot and dangerous. I see the reports say that 90-118 people died even before the storm. A bus of elderly started on fire, and all were killed. These same roads and feeder roads that people traveled on are now under water in this storm. Evacuation of so many people is impossible. And, remember no one could understand how the other factors would play in this storm [unprecedented rain, recent development boom]. The weather men do an excellent job of predicting, but they can’t be sure. People prepared the best they could. Some did bug out.

I’m proud of how those in authority handled and are handling things, and I’m here. I can tell you now, after living through Allison, Houston has a long row to hoe, and at this writing, until mean big brother Harvey decides to quit picking on us and go away, we won’t know how bad things will be. We will recover because Houston is stronger than Harvey, but one thing is sure, in my book, this is no one’s fault.

August 29, 1:00 AM [emphasis mine]

So far, the confirmed death toll from Harvey is just 14 people. If Rita is any indication as to what a full evacuation would have looked like, and given that the roads where those traffic jams occurred have flooded, the decision not to evacuate any but those at highest risk may have saved thousands of lives.

Climate Change

A storm like Harvey could have happened before anthropogenic climate change. We have no record of such a thing, but perhaps one occurred before or record began. But there are several factors which make a Harvey-type storm more likely than before we monkeyed with the climate.

First, the Gulf of Mexico is warmer now, which makes deep pools of very warm water in the Gulf much more likely. When a hurricane moves across such  pool, it can intensify suddenly–which is exactly what Harvey did. It’s also what both Katrina and Rita did, as each grew dramatically in much the same way.

Second, the air is warmer now, and warmer air carries more moisture, which means more rain. In hurricanes, it’s the wind that gets the press–we rate hurricane intensity by wind speed–but it’s the water that causes the damage. Many storms, notably Irene, a few years ago, cause their most severe damage after being downgraded out of hurricane status, simply by raining a lot. Harvey is another in this pattern.

Third, the reason Harvey parked itself right over Houston for so long is that it was trapped between two high pressure zones. This scenario ought to sound familiar, because persistent high pressure zones have been involved in almost every severe weather story I’ve covered for years, now. Droughts, heat waves, snow storms, extra-tropical rainstorms, and hurricanes have all made the transition from bad weather to unprecedented disaster, in part, because they stayed in the same place longer than normal–because of persistent blocking highs. And while it hasn’t been confirmed yet, the changes in the jet stream that create persistent blocking highs (and misplaced polar vortexes and weird, hurricane-like winter storms) may be being caused by melting of the sea ice in the arctic.

One final thing to consider; yes, we are stronger than Harvey. We were stronger than Katrina, Irene, and Sandy. We were stronger than the California superdrought that drained a state’s reservoirs, the atmospheric river storms that filled those reservoirs up again and nearly breached the Oroville dam, the heat waves that grounded airplanes in Phoenix two years running, shockingly intense wildfires, and the floods in Baton Rouge that acted like a hurricane but weren’t. But how much longer are we going to keep our strength up as these things become more likely and occur more often?

Can’t we just bite the bullet and stop warming the atmosphere?