The Climate in Emergency

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


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A Shot in the Dark

It’s been an interesting week in the news. My nation’s most recent mass shooting incident triggered the beginnings of a promising student protest movement.  The release of the groundbreaking superhero comic, Black Panther, spoke to America’s “original sin” in a way no other movie ever has. Temperatures in the Mid-Atlantic region are predicted to hit thirty degrees above normal, breaking records set…last year. The prediction is similar for the entire Eastern US, including the Lower Hudson Valley and Boston. And some states are making serious attempts to remove climate change from required school curricula.

I am very glad that young people are organizing to protect their lives in school. The issue needs attention, and the political experience they gain now will make them better citizens. I am very glad that there is now a very popular movie about brilliant and powerful black people and all of the other things Black Panther is about. It’s a rare mainstream acknowledgement of some important truths. Plus, I just saw the movie and it’s fantastic.

But where is climate change in all of this? Climate change threatens the lives of school children. Climate change is one of the agents by which the disenfranchised are abused. And I’m not hearing anyone talking about it. For a while there, climate change was getting on people’s radar. Political demonstrations, cultural references, frequent news coverage….It all seems to be backing off.

Is something being  silenced?

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Solar Impulses

This past week, I saw a documentary on the flight of the Solar Impulse 2, the first airplane to circumnavigate the globe without fuel–the plane is solar powered. It’s a great story.

The visionary behind the project, Bertrand Piccard, is the latest in a long line of brilliant dare-devil explorers who have been building and piloting record-breaking balloons and submarines and the like for generations. His great-uncle, Jean Felix Piccard, was the historical inspiration for that Star Trek captain with a very similar name, and the real and fictional Piccards actually bear a bizarre physical resemblance; Bertrand looks like a relative of Jean-Luc. The airplane itself is one of those objects everybody insisted could never be built, could never work–to have enough solar cells to generate enough power, the plane would have to be very big, but big planes need even more power to fly, so the plane would have to be even bigger, which would mean…unless the plane were absurdly light and under-powered (and still big), in which case it would be hard to fly and prone to break if a cloud looked at it funny. Impossible. But Captain Piccard assembled a team, said “make it so,” and they did, and it worked, and there you go.

Just to give everyone due credit, the plane had two pilots who took turns, Mr. Piccard and Andre Borschberg, and a large team of engineers and other mission-support personnel, without whom the project would not have worked.

Obviously, part of the motivation for the whole project was the coolness factor. Mountaineers climb Everest “because it’s there,” and Piccards probably invent and pilot unusual flying machines or submarines for similar reasons. But the specific mission for the Solar Impulse 2, and the thing that brings it under the purview of this blog, was to raise awareness for renewable energy. While the plane itself is far from practical (it can only carry a single person–the pilot–and only under ideal conditions), its existence suggests greater things to come and, as Mr. Piccard is fond of pointing out, everything is more difficult in the sky, so if solar power can work even marginally for an airplane, there’s no excuse for not using it on the ground.

All of this is laudable. There is a long history of impractical-seeming exploration leading to very practical technical innovation, and there is much to be said for crazy stunts as a way to get media attention. If flying around the world in an extremely fragile experimental airplane gets you on TV saying “climate change is real and important and we have to do something!” than I am all for it. These people are doing it right, making a difference.

Also, based on his appearance on the documentary, I find Bertand Piccard impossible not to like. He positively glows with a kind of driven, excitement, the kind of delighted passion usually called “childlike,” except it’s also obvious that you’d better not get in his way. He’s probably hard to live with, but as I don’t have to live with him, I’m free to just think he’s really cool. And he’s good-looking, so that helps.

I point all this out in order to make sure my next question is not misunderstood:

What was the carbon footprint of this project?

I suspect somebody has calculated the answer, but finding the number is not really the point–I’m sure the footprint was huge. Consider just two aspects of the project. First, the plane took off from Abu Dhabi, and eventually returned there, triumphant, but that’s not where it was built. The documentary clearly showed the Solar Impulse 2 arriving at the Abu Dhabi airport inside the belly of a giant cargo plane. That cargo plane was not solar powered. Second, the Solar Impulse 2 can carry only one human at a time, but it had two pilots who alternated. One pilot would land and, I assume, go sleep in a hotel for three days, and the next pilot would board and take off. That means that the relief pilot, not to mention the ground crew and the specialized portable hanger, must have flown (in non-solar aircraft) to the meeting place. Since weeks or months sometimes went by between the legs of the journey, the pilots probably flew home sometimes, too.

It’s not that the project was necessarily carbon-heavy as such things go, but it obviously wasn’t carbon-light, either, and it definitely wasn’t a flight around the world using no fuel. The airplane that doesn’t use fuel requires the support of those that do.

As I said, the value of the project was as an early proof of concept and as a stunt designed to trigger necessary conversations. As such, it was a good and important project. But I’d like to suggest a follow-up:

How about a team of people go around the world ACTUALLY with zero fossil fuel?

Or, better yet, several teams, and have them race? They’ll be walking, biking, sailing, rafting, and in some areas using plug-in hybrid cars and possibly some experimental technology. The race will provide both audience interest and an incentive for teams to innovate, rather than simply walking and sailing for three or four years. Infrastructure and technology will be tested and explored, possibly triggering useful innovations, such as bike lanes and walkable city designs. Local people will appear in interviews on BBC and PBS with translators doing voice-overs. It will be great.

Because we know that climate change isn’t really a technological problem. Better technology will help, but we could do a lot more to combat climate change with the technology we have. The problem is cultural and political, and requires cultural and political solutions.

A big, attention-grabbing demonstration of the zero-carbon transportation tools we already have might help.


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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.

 

 


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New Year, New Normal

It’s cold.

What I mean is that the weather is colder than its been recently in the part of the world where I happen to be. The simple answer to those who insist the world can’t be warming while they personally shiver is that climate change involves increased extremes, including the occasional extreme cold snap. But it’s also possible for one area to have record-breaking cold even as the world on average is unusually warm, as has happened in recent years. And it’s possible for conditions to seem unusually cold even while still above the 20th century average, because we’ve grown used to warmer conditions still.

I haven’t checked to see which of these concepts applied to New Years’ Day in Eastern Maryland, 2018.

What I know is that I turned up on Assateague Island for the annual New Years’ Day Beachwalk, which my husband usually leads, and conditions were brilliant, bright, and beautiful. Clear, blue sky, a stiff breeze whipping the waves to photogenic whitecaps, and a windchill of seven degrees.

I want to emphasize that this event is not supposed to be masochistic. It’s not like the Polar Bear Plunge, in nearby Ocean City, where people actually jump in the water on the first of January, no, it’s an educational walk where you get to stroll along with a naturalist, learning about the island’s history, its sand, and its sea shells. Some years over three hundred people show up.

This year, we had 34 people, almost half of them organizers, volunteers, and hangers-on. My husband did his best, under the circumstances, but there was no shelter from the wind anywhere, and people were having trouble concentrating because it was just too cold. He cut the walk in half and brought everyone back to the starting point early for hot chocolate. Then he and I went home and had Chinese take-out.

Everything everybody says about cold snaps in a warming world is true–climate change involves extremes in all directions, it can be cold here but warm elsewhere, and these temps only seem as cold as they do because everything has been so warm of late.

But what happens when we get used to warm weather?

It’s not like I’ve never experienced single-digit temps before–I used to live in New Hampshire, where I regularly biked to and from school in the winter. Cold was normal, and seldom bothered me. I dressed for the cold as a matter of routine. But now…do I need a hat, or is a hood good enough? How thick do my socks need to be? How many layers do I need? I can’t quite remember. I’m out of practice. Give me another week or two of this and it will all come back to me, but Monday morning I wasn’t there yet.

Whether a given temperature is historically normal or globally notable is less important for most people than whether it’s been typical lately. A surprising cold snap in Maryland might involve temperatures that are perfectly normal for Vermont or New Hampshire, but that doesn’t mean the Marylanders have adequate coats, hats, and gloves, nor do they necessarily have lifestyles and habits that make sense in such temperatures. Where a New Englander might have recreational activities that require cold temps (like ice fishing), on the Lower Eastern Shore, this kind of weather disrupts everybody’s plans. Sometimes the surprising cold is dangerous.

The way changing climate works, cold weather doesn’t go away, it just gets less likely. While I haven’t seen any figures on the matter, I’m wondering if rising average temperatures are resulting in more disruption–and more danger–when cold snaps do occur.


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It’s Time

Funny how the tricks of the calendar can have such an effect on the mind. It’s like that old joke—you have a birthday everyone asks how it feels to be a year older. Of course, you are nothing of the kind—but it feels meaningful. Jimmy Buffet had a birthday yesterday. So did Jesus Christ, at least according to many of his followers….

And because of a trick of the calendar, those followers now feel as though the baby, Jesus has just now been born. As though everything that baby stands for is just now irrupted into the world, and for his sake many of them make a serious attempt to live love more deeply now.

What changed? Nothing, except the minds of those willing to use a trick of the calendar to foster change.

Today I’m tired, and perhaps somewhat grumpy, and I’ve spent several hours now in from of the computer, ostensibly working, unable to think of anything.

I’ve spent most of the past year mired in my own head, unable to do much of anything, despite our living in a world where so much needs to be done.

But New Years’ Day is coming up, and there are ways to make changes stick, ways to instill new habits, new practices—you can look these things up on line, there are plenty of ways to make a New Years’ resolution more likely to stick. Let’s use the time we have in which to act; make climate action a priority.

Who’s with me?


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Deck the Halls

Do you have your holiday shopping done yet? Your gift list completed, your menu planned?

On the off-chance that you don’t (it’s ok, I’m not done yet, either), I thought I’d say a few words about keeping your holiday carbon footprint down. There are a lot of sites out there recommending “green” tips, but many of them don’t have much in the way of context–sure, this or that practice might be “green,” but which is the most important? Where is most of the holiday footprint located? What changes can give us the biggest bang for our buck?

I was able to find one article that provides that context–it is about ten years old and British, so there might be some discrepancies with the situation these days in the United States. But many of my readers are not in America anyway, and would have to make some adjustments even if my source material was from the same country as I am.

The reason I’m focusing on Christmas is not just an attempt to be seasonal on my part–for one thing, not all my readers celebrate Christmas. But this one holiday inspires more consumption–and thus more carbon emissions–than almost any other time of year. According to The Carbon Cost of Christmas, 5.5% of Britain’s total annual carbon footprint occurs over Christmas alone. Note that 5.5% of 365 is just over 20. Since the author of that article was counting “Christmas season” as only three days long (Christmas Eve, Christmas Day, and Boxing Day), that means cramming 20 days’ worth of emissions into the equivalent of a long weekend.

By the same token, a significant reduction in your Christmas carbon footprint could have a significant influence on your whole year.

Where Does Christmas Carbon Come From?

Cost of Christmas lists four categories of Christmas activities with their average per person carbon costs in kilograms as follows:

Christmas shopping = 310

Decorative lights = 218

Car travel = 96

Holiday food = 26

Since the article doesn’t list exactly how these numbers were derived, it is difficult to be sure how accurate they remain ten years later. I suspect the footprint of lighting may have shrunk somewhat with the popularity of LEDs–though it’s also possible that people have simply added more lights and still use just as much electricity as ever. Also, those inflatable lawn ornaments, the ones that must be constantly hooked to a running blower, have gotten popular in the last five years (at least in the US) and must be demanding a significant amount of electricity.

Still, I suspect that even if the numbers have changed, the order of these categories has not–simply because shopping and lighting each remain extravagant at this time of year (for those who can afford extravagance). That means these are the areas where reduction can give us a very satisfying bang. Not that we’re going to ignore the other two areas.

Cost of Christmas estimates that a reduction of per-person holiday-related emissions of 372 kg of carbon dioxide is not unreasonable. Since their original carbon cost estimate was 650 kg, that’s almost cutting emissions in half–which still leaves the three days of Christmas responsible for over a week’s worth of emissions, but still, that’s a huge improvement.

(Note that these kilograms of carbon dioxide probably do not all come loose during the three days of Christmas–holiday travel, for example, must occur before and after the holiday, not during–but these are emissions made for the sake of those three days.)

Lowering the Cost of Christmas

What strikes me reading the Cost of Christmas is that much of the cost is attributable to things that don’t really add to anybody’s enjoyment: Brits evidently spend a total of £4 billion every year on unwanted Christmas gifts, an average of 92 per person. More to the point, those gifts are responsible for 4.8 million tonnes (that’s almost 5.3 million American tons) of carbon dioxide, or 80 kg per person.

And those lights? A lot of people keep them on all night long, sundown to sun-up. During the majority of those hours, most people are either asleep or inside their dwellings and not looking at anyone’s outside lighting. That suggests that something on the order of two hundred kilograms of carbon emissions per person per season are emitted in order to make light that nobody looks at.

More emissions (the number is significant but much smaller) involves food that nobody eats.

Are there places we can cut our holiday extravagance that actually might involve some personal sacrifice? Yeah, sure, and since said sacrifice is not very painful (and much less painful than climate change), we should have at it. But the low-hanging fruit here is definitely the emissions that bring nobody any use or pleasure at all.

Practical Tips

As you go through your holiday preparations this year, be sure to take certain steps–or, if you’ve already made those purchases, take notes for next year. Some of these steps are fairly obvious–if your electric bill normally spikes in December, adjust your light display so that it doesn’t. My husband and I have a modest display, but we also get all our electricity from landfill gas generation, meaning that our electricity is actually carbon negative. See if something similar is available in your area.

You can get a lot of useful tips from lots of great websites. One advantage of holiday “greening” is that it’s a fairly simple way to introduce possible lifestyle changes to other people. For example, you can show up to holiday parties with gifts in reusable decorative bags, rather than wasteful wrapping paper. If the party is likely to involve plastic plates and silverware, bring your own table setting from home (yes, my husband and I do this). And so on. If people ask why you’re being weird, tell them.

As far as gift-giving goes, part of the problem is doubtless poor judgment on the part of the giver. If you have no idea what to give someone, don’t guess–ask, or give a gift card. But I suspect part of the problem is a certain sense of obligation. You don’t really want or need much, so you ask for something you don’t really care all that much about.

Am I right?

Seriously, most people I know–myself included–have to be begged for Christmas wish lists most years. This year, there are some things I want, but not many.

So, if you’re in the position of not really wanting anything, don’t ask for things you don’t really want. Don’t say “I don’t want anything” either, as no one will believe you. Instead, ask for experiences you’ll enjoy (dinner at a favorite restaurant, for example) or ask for charitable donations made in your name.

My go-to wish-list items are requests for donations to the Union of Concerned Scientists, the League of Conservation Voters, and the Environmental Defense Fund. If I add a fourth, it’s the ACLU.

The other thing to consider is carbon budgeting–if it’s really important to you to travel hundreds of miles to go see family at this time of year (highly understandable), then go by the lowest-carbon means of travel you can, and cut back your travel at other times of year in order to leave room in your carbon budget for the holidays.

It Came Without Boxes, Ribbons, or Tags!

In How the Grinch Stole Christmas, the moral of the story is that Christmas does not require anything in the way of materialistic splendor. Even if you have nothing, you can have Christmas.

It’s worth noting that a lot of people pretty much do have nothing. There are a lot of people who simply can’t afford to spend large amounts of money on unwanted gifts or lights nobody looks at. I realize that being asked to scale back for the sake of the planet is very disheartening when you don’t have any back to scale.

If that’s your situation, then let me say you’re not alone. Plenty of folks don’t have a lot of fat to cut. The good news, if there is any, is that you’re already there. You’re green.

 


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Oh, Christmas Tree!

The other day, my mother asked me whether she ought to switch to artificial an Christmas tree, for environmental reasons. This question has been addressed by other authors (please check those links for my source information), and the short answer is “no.”

(Don’t you like straightforward answers, Mom?)

But why the answer is no is interesting, as are the exceptions–my husband and I use an artificial tree, for example.

Natural Christmas Trees

You’d think this would start with a side-by-side comparison of pros and cons of each option. After all, using a natural tree involves cutting down a tree, and that can’t be good, right? But while I admit that cutting is bad for the individual tree, that’s not how conservation works. The health of the land as a whole doesn’t depend on the longevity of individual trees, but on the functioning of a whole system. While it’s possible to imagine Christmas trees being cut in environmentally destructive circumstances, I’ve never actually heard of the Christmas tree trade being a major driver of deforestation. Instead, Christmas trees are generally grown on farms–and a Christmas tree farm is a much better bet, environmentally speaking, than, say, a housing development. The growing trees do provide some wildlife habitat, protect and develop soil, and sequester carbon.

Most of the carbon sequestered by a growing tree is, of course, released when the tree dies and the wood rots or burns, but the farm as a whole holds carbon as generations of Christmas trees grow there. And while transporting the cut tree does involve carbon emissions, but depending on how far the trees have to travel and what happens to them after Christmas, these emissions can be minimal. Typically, half of a tree’s total carbon footprint comes from the trip the family makes to bring it home. If you drive less than ten miles to get the tree, and especially if the tree is mulched afterwards, rather than landfilled, your Christmas tree can actually be carbon-negative–that it, it fights global warming, rather than adding to it.

Even if you do drive farther for your tree, its carbon footprint is still dramatically smaller than that of an artificial tree.

Artificial Trees

It might be possible to produce sustainable artificial Christmas trees, but that’s not what is available in the stores. Artificial trees are almost always made of a combination of PVC plastic and steel, which are both carbon-intensive materials. They are recyclable, but virtually no recycling centers are prepared to disentangle the two, so artificial trees are typically treated as trash. The trees are also almost all made in China, meaning that they travel much farther (at a much greater carbon cost) than real trees normally do.

It is true that real trees are used only once and artificial trees can be used over and over–but if the live tree you’re comparing it to was carbon-negative, that’s irrelevant. The real tree is always going to be better. As for comparisons with live trees that do have carbon costs, estimates vary from five to 20 years, as to how many years an artificial tree must be used before its annual carbon cost starts to equal that of the real tree.

Most people replace their artificial trees after only six years.

Exceptional Trees

Whether artificial or real trees are better in the abstract is one question. “Which tree should I use?” is a completely different question. For example, our artificial tree is second-hand, and it likely would have been thrown away had we not taken it. Arguably, the environmental cost of the tree belongs at the feet of its original owners, since their decision not only paid for its manufacture, but also made certain it would one day need to be disposed of. We got the tree for free, environmentally speaking, and it saved us from having to buy any tree of any kind for well over ten years, now (my husband doesn’t remember when he got it, but it was here when I arrived).

You could also make your own artificial tree out of sustainably-sourced materials. You could also decorate a houseplant as your Christmas tree–balled and burlapped trees usually die, and spruces grown in pots as Christmas trees are only slightly more likely to make it, but you could decorate a Norfolk pine or another species that does well as a houseplant. You can do a little research to determine whether locally-grown trees are available in your area, whether Christmas trees can be mulched in your area (if you have a yard, you can also set your post-Christmas tree outside to provide cover for wild birds) and, if you want a live tree, you can make sure to pick it up from someplace less than ten miles from home (depending on the gas mileage of your vehicle).

In short, which tree you should use (assuming you want one at all) depends, in part, on your situation.