The Climate in Emergency

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


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Innumeracy Again

Some weeks ago, I wrote a post calling attention to innumeracy–the inability to think well about numbers. It’s a common problem, and unlike illiteracy it has little to do with basic education. That is, innumeracy could be addressed with education, but it usually isn’t, so you can be well-educated and even good at math and still be functionally innumerate.

Here is an example; when the Australia fires were in the news, it was easy to get figures for the number of acres that were currently on fire, but news stories typically didn’t mention what percentage of Australia’s area that was–or, since much of Australia is open desert, how much of the country’s forests were on fire, or how much had burned already total. A moment’s thought will show the relevance of these questions, and yet reporters consistently assumed nobody would want to know.

That’s innumeracy.

If you feel personally called out by this post, please stay with me; innumeracy is a serious problem, but it’s ridiculously common problem that has nothing to do with your overall intelligence. Basically, most human beings find numbers counter-intuitive, and very few of us  are ever taught how to counteract the natural mistakes we make on the subject. The first step is to realize you are making natural mistakes–it’s a bit like learning how to back up with a trailer, a thing which everybody does disastrously wrong unless somebody tells them that they have to turn the wheel the opposite way from what makes sense.

The reason I’m bringing this up again today is I’ve noticed a similar problem with the new coronavirus. It’s easy to get figures for the number of people infected, the number of people killed, broken down by country or even by state, but hard to find context for those numbers.

I’m also seeing a lot of social media posts that present scary numbers without context.

COVID-19 in Context

First it was the posts insisting that COVID-19 isn’t as bad as seasonal flu because seasonal flu has killed so many more people. I haven’t seen those in a while, now, so perhaps more people are realizing that total number of people already killed isn’t the relevant number–it’s the number of people who could be killed over the course of the outbreak, and the number of people who will get sick enough to require hospital care (the prospect looms of running out of hospital beds).

Now, what I’m seeing is graphs showing how fast the outbreak is growing in the US as compared to other countries, but without mention of the population size of each country.

Yes, we might have the number of infections Italy did a few weeks before their hospitals got over-run, but that doesn’t mean we have the same number of weeks before ours are over-run. The US population is over five times that of Italy. Everything else being equal, we should have five times the number of hospital beds and more time before those beds are all occupied (even if they could be all occupied eventually).

Of course, everything else is not equal. I have no idea how the Italian medical infrastructure compares to that of the US, and I am aware that neither country has its COVID cases spread evenly throughout the population. The total number of ventilators in a country is not as important as the number of ventilators in one hospital, and if that hospital serves an area experiencing a concentrated outbreak (such as that in New York State) it could well be over-run even if other hospitals in the country have no COVID cases at all.

I’m also not trying to argue that the situation isn’t scary. It is scary. We’re in a genuine emergency whose final outcome is far from clear at this point. What I am saying is that we’ll be better equipped to deal with the emergency if we’re asking the right questions.

What I want to know, for any given area (the US, the whole planet, my town, etc.),:

1. What percentage of the overall population is currently seriously ill? What percentage is quarantined?

2. How fast is the disease spreading currently? How is that rate changing?

3. What percentage of the intensive care capacity is being used and how is that number changing over time?

These numbers together give a picture of how close we are to catastrophe and how the US outbreak compares to that of other countries–and would give ordinary people tools to demand specific things of their government, such as more intensive restrictions if the spread is still too fast, or increased medical capacity if a local area is in danger of being over-run.

But I’m not seeing these numbers.

Remember Climate Change?

So why, other than a desire to be topical, am I talking about this disease?

Partly, yes, I want to be topical. I hope to return to more traditional subjects in next week’s post, but I do what to acknowledge the topic on everyone’s minds, and that’s the pandemic. But also, as I explained recently, climate change and pandemic are closely related topics; our ability to deal with each is being inhibited by a willful ignorance and distrust of science, a distrust of government leadership, and a Federal government that by and large refuses to provide effective leadership and sometimes becomes part of the problem.

The reductions in pollution we’re seeing as economies are forcibly shut down are temporary, but if this disease forces us to start paying attention to science, to math, and to the demands of reality itself, that may have lasting value.


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Why Corona Is Less Scary than Climate

A purplish sphere is partially visible in the lower left-hand corner of a black but white-speckled field. The sphere has various blue and green protuberences. The image is a representation of the coronavirus and is similar to images often used in news stories about the new coronavirus.

Photo by Fusion Medical Animation on Unsplash

OK, to be clear? I don’t mean that you are less scared of COVID19 than of climate change. You feel however you feel. That’s legitimate. And certainly COVID19 is a more immediate problem–I know multiple people with underlying health issues such that they would probably not survive the disease. I know others on the economic edge who might not survive this recession, unless policy becomes a good deal wiser than it’s been.

And while I personally am more worried about climate, it’s not that I’m not worried about the pandemic–and it’s not that my relative health and security lead me to dismiss others’ troubles as no big deal.

What the issue is, why I say climate change is scarier, is the topic of this post.

Presenting My Credentials

You know me as a climate change blogger, but I’m also a novelist, and my second novel, Ecological Memory, explores the aftermath of a global pandemic. My fiction is heavily researched and as scientifically accurate as possible, so I have read extensively in virology, epidemiology, and the history of real pandemics. I’m no expert, but I’m no stranger to the topic, either–this is not the first time I’ve thought about what pandemics can do.

For example, my fictional pandemic (which has no name besides “the pandemic”) has certain features in common with COVID19:

  • A mortality rate that seems low in comparison to obvious nightmares, like Ebola
  • An initial infectious period without definitive symptoms
  • An initial appearance in an urban area
  • Relatively mild expression in some victims, such that some infected people don’t go to the doctor and don’t get tested
  • Symptoms that closely mimic existing common diseases, making proper diagnosis without testing impossible
  • The primary threat of the disease is not its total mortality but rather the way it puts pressure on existing societal and medical vulnerabilities (pre-existing health threats, bigotry, economic disparity, medical infrastructure problems, and overall economic instability).

It’s not that I’m prescient, it’s that I did my homework. Another global pandemic was inevitable the same way another giant earthquake in San Francisco is inevitable–and another after that. And to successfully evade the sophisticated systems already put in place to prevent pandemic, a disease has to have certain characteristics. I simply crafted my fiction as a worst-case scenario of what all the relevant experts considered likely.

(To be clear, COVID19 is not the worst case come to life, though it’s bad enough; the fictional version also featured a longer initial infectious period, a much higher infection rate, a significantly higher mortality rate, and an initial appearance in multiple urban areas simultaneously due to human nefariousness)

So I hope you’ll consider my remarks well-informed.

5 Reasons Climate Change Is Scarier Than COVID19

A large crown of people is vaguely visible, though no faces appear clearly. The lighting suggests sunlight, outdoors, presumably a political demonstration. Held above the crowd on a thin stick is a hand-made sign, written in green, blue, and red marker on white cardboard. It reads "The climate is changing so should we! #ACTNOW." The word "changing" is underlined and the symbol of Extinction Rebellion is next to it.

Photo by Markus Spiske on Unsplash

I hope you’ll forgive the click-baity subheading–it fits the material, and I do hope it attracts search engines.

1. Climate Change Exacerbates Pandemics

While COVID19 specifically is not caused by climate change, an increased risk of disease outbreak is a symptom of anthropogenic climate change, for various reasons. So, if you don’t like pandemics, you have to do something about climate change.

2. That Which Exacerbates Pandemics also Exacerbates Climate Change

We’re also seeing how politicized anti-science sentiment is fouling up efforts to deal with COVID19 in the United States. Our country faces the crisis without informed, organized leadership at the Federal level because President Trump disbanded the group that would have provided such leadership, undoing the lessons learned from the Ebola threat some years ago. I’m not sure why he did that–possibly it was just part of undoing President Obama’s legacy–but it was part of a larger pattern of stripping science out of the Federal government. President Trump’s response to COVID19 has, at least until recently, been to deny the severity of the problem, and even to interfere with efforts to address the problem. Meanwhile, politically conservative citizens are showing a tendency to treat the whole coronavirus issue as just another liberal plot.

The parallel with the national response to climate change is striking.

I don’t see how pandemic denial benefits anybody. Like the panic-buying of toilet paper, it’s a troubling response that has no obvious motive. I have no hypothesis to offer on the toilet paper thing, but science denial in general does have a motive; undermining public faith in science, scientists, and science-based governmental leadership has the direct effect of torpedoing any possibility of American leadership on climate change–and delaying climate action does mean money in the bank for certain people.

I’m not sure I’d go so far as to say pandemic denial is a deliberate part of an anti-climate plot. It may simply be that once one has accepted the anti-science, anti-government premise, any science-based warning issued by a government agency or by the “liberal media” looks like a hoax. My country’s pandemic response may be collateral damage in an unrelated fight. But it’s also possible that indiscriminate anti-science messaging has been the medium for creating climate denial, meaning that our current crisis may indeed be being deliberately used to some extent. Either way, as I’ve discussed before, climate denial is the deliberate creation of certain people with financial ties to the fossil fuel industry, and those financial ties are not likely a coincidence.

If the United States had an aggressive climate action policy in place and was already leading the way towards global decarbonization, we would not have hamstrung our efforts at pandemic response by stripping science from the Federal government.

If you don’t like pandemics, you have to support science-based government policy, and that means supporting climate action also.

3. Those Who Are Hurt by COVID19 Are Also Hurt by Climate Change

COVID19 is not like rain, falling on the just and the unjust alike. It’s more like a flood that ruins things for the already vulnerable disproportionately. It is the elderly and the already-ill who are most likely to get seriously ill, or even die, from the new coronavirus. It is the economically marginalized who are most likely to be damaged by the closures and other economic issues of our response to the virus. It is the politically marginalized who will bear the brunt of suffering caused by shortages, medical rationing, and general panic, should these be allowed to develop by short-sighted policy. I have already discussed how it is these same groups who stand to lose the most from climate change.

The problem is that our society has certain weak points, and any type of severe stress, be it increased severe weather, a public health crisis, or some other thing, collapses those weak points first. The people most exposed to those points of strain suffer as a result.

If you don’t like the suffering caused by pandemics, you have to take climate justice seriously as well.

4. That Which Mitigates Pandemic Risk Also Mitigates Climate Change

A lovely photo of a spruce-dominated forest. Sunlight streams in from the side, evidently from a nearby clearing. The shade in the forest is deep, but the understory is filled with grass and broad-leafed shrubs and saplings, all apparently taking advantage of the light from the nearby clearing. The image is quite lovely.

Photo by Sebastian Unrau on Unsplash

As the previous three points imply, if we had been taking the risk of pandemic more seriously, we would be further along with climate action now. And had we been taking climate change seriously, pandemic preparedness would have occurred almost as a matter of course.

Here are several major steps which my country (and likely others, though I’m less in position to comment) should have taken already taken, and could still take.

1. Decarbonize the Economy

Reducing greenhouse gas emissions is the step without which all other steps constitute rearranging deck chairs on the Titanic. You know the old saying–if you find yourself at the bottom of a hole, stop digging! And the simplest, most effective way to substantially reduce emissions is to transition away from fossil fuels.

Sustainable use of renewable resources, not unsustainable harvesting of wood, large-scale use of lithium batteries, or other such problematic option, must be the future, a shift which, yes, will require a massive restructuring of the economy. At this point, such restructuring is unlikely to be fun, but the alternative is much worse.

However, it’s worth noting two likely outcomes of such restructuring.

One is that non-essential long-distance travel is likely to get prohibitively expensive. Another outcome is that as the transportation of goods gets more expensive, economies will become regional rather than global.

Less long-distance travel will make us less vulnerable to pandemic. Pandemics will still be possible, but they will spread more slowly, increasing the likelihood of successful intervention.

Regional economies will be less likely to collapse in response to disasters in other regions (long-distance shipment of emergency aid will still be possible).

A low-carbon world will be less vulnerable to the sort of crisis we are seeing now.

2. Plan for Disaster

Climate change increases the likelihood of all sorts of disasters, including flood, fire, famine, and, yes, pestilence. Unfortunately, cutting our carbon habit is not likely to save us from the effects of climate change over the next few decades, because there is a delay in the climate’s response. We have to decarbonize and mitigate the damage we’re already in line for, and that includes planning for disasters of a scale and frequency we haven’t seen yet.

Lots of disasters of all types require the rapid mobilization of resources, the efficient sharing of information both between agencies and with the public, and the prompt and proper care of large numbers of casualties and displaced or isolated persons.

All of the above is also critical in a pandemic.

3. Build for Disaster

Just to elaborate on the point about planning for disaster–part of that planning includes building facilities that can be rapidly converted to hospitals, shelters, or whatever else might be necessary. In ordinary times, such facilities could be used as convention centers, hotels, or whatever else, provided a mechanism was in place for rapid conversion as needed.

The United States has precedent for such dual-purpose preparedness–our interstate road system was designed to function as a network of emergency air strips and military transport routes in case of war. So it’s not as though a network of overflow hospitals would need to sit empty and useless between disasters.

4. Allow Redundancy

A central value in a capitalist society is efficiency. Why have hundreds of little companies when one big one can make widgets, or whatever else, cheaper? Why build capacity we don’t need? Why offer services that don’t turn a profit, or at least pay for themselves? The push, in recent years, to turn more and more of our society over to the private sector is based on the premise that everything ought to be run like a business because businesses are efficient and everything else ought to be as well.

Of course we should avoid waste, but not all inefficiency is wasteful. Redundancy is not wasteful–it’s critical.

Redundancy is a necessary feature of all resilient systems. We have two kidneys, though we can get by with just one, and a good thing, too. Healthy ecosystems have more than one species that eats bugs and more than one species of plant for bugs to eat. Any given part of any system could fail, and when it does, there needs to be some kind of back-up. It’s not that natural systems are smart in any deliberate way, it’s that overly-efficient systems get edited out by the demands of reality. Our efficient society, dominated as it is by just a handful of large companies, just a handful of wealthy families, and fewer and fewer media outlets–and fewer hospitals–is an editing job just waiting to happen.

We could create back-ups as part of disaster-preparedness, and should, but we should also allow redundancy to develop naturally. Stop insisting that everything be run like a business. Stop cutting regulations and protections in the name of efficiency. Stop favoring policies that favor consolidation.

Community-based hospitals with extra beds and staff who aren’t exhausted will be one result.

5. Be Just

Of course justice at all levels is important for its own sake. And, as mentioned, justice is a major part of both climate change mitigation and pandemic harm reduction. But any policy that leaves behind any segment of society is not going to have the cooperation of the public–and it’s not going to work. No one should ever be forced to choose between saving the planet–or stopping the pandemic–and their own civil rights.

5. And the Biggest Reason Climate Change Is Scarier?

I’m sure you see the pattern I’m trying to draw, here; climate change is at least as scary as COVID19 because the two are closely connected. All the ways the virus can hurt you are also ways climate can hurt you, and the neglect that has left us vulnerable to the one has also given us the other.

But why did I say climate change is scarier?

Because COVID19 only kills human beings.

This is the famous image of the Earth as seen from the Apollo spacecraft on its way to the Moon. Here, it has been cropped so as to vaguely echo the image of the coronavirus used at the beginning of the post.

Photo by The New York Public Library on Unsplash

 

 


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A Family Expecting

I first posted “A Family Expecting” shortly after the birth of my nephew, several years ago. I have re-posted it occasionally since then, and rewritten it at least once under a new title. I’m re-posting again now for two reasons; one, today has been two busy to write, two, the piece is still a good way to remind people that what we’re doing really matters.  Although this story is a fantasy, it is based on the published results of climate models. Please check out the original for the research links posted at the bottom

Yesterday, my first nephew was born. He is small and wrinkled and has acne on his nose. He has wispy black hair and silvery-blue eyes. He knows the voices of his family and the scents and sounds of the hospital. He does not know about his home, going to school, or getting a job. He doesn’t know about casual friends, mean people, or birthday cake. He doesn’t know what the world will be like for him.

Neither do we, obviously, but if he lives to see his 89th birthday then his life will touch the end of the century, spanning the same period of time across which many climate models dare to predict. He comes from farming people in the Piedmont of the Mid-Atlantic. If he stays here and inherits his parents’ farm, as he might, then his life will also be the life of this landscape. What will he see?

This child will go home soon, and become the son of the land. He’ll rest in a cradle on the floor of a barn, his mother rocking him with one bare foot as she directs customers picking up vegetables in June. In two or three years, he’ll carry handfuls of squash guts as gifts for the chickens and a rooster as tall as he is will look him in the eye and decide he’s ok. He’ll listen to his parents worry about droughts. He’ll learn to hope the heavy rains don’t rot the tomatoes and that rising gas prices don’t break the bank. There will likely be more such worries as he gets older. Summers will be hotter. His mother will say it didn’t used to be like this, but grown-ups always say that.

According to the IPCC, by the time he’s a teenager, temperatures in the Mid-Atlantic will average maybe two degrees higher than they did during his mother’s childhood. That does not sound like much, but averages rarely do. One degree can turn a pretty snow into a destructive ice storm.

Warming, in and of itself, will be good for the crops; only a local rise of about five degrees Fahrenheit or more hurts productivity. That’s unlikely to happen here until my nephew is a very old man. But the Great Plains may warm faster, enough to cause a problem; he could study the shifting agricultural economics in college.

Our area could either get wetter or drier. Parts of northern and central Mexico will almost certainly get drier, maybe dramatically so. These areas are dry already, so I imagine a lot more people will start heading north. My nephew will discuss the refugee problem with his friends, lean on his shovel in the morning sun, and wonder if the United States has a responsibility to keep Mexicans from dying when Congress is already deadlocked over how to pay for the flooding in New England. Seems you can’t keep a bridge built in Vermont, anymore. He takes off his sun hat and scratches his thinning hair.

Years pass. My nephew thinks about his upcoming fiftieth birthday, and also about New York City, where three of his grandparents grew up. It’s turning into a ghetto. It’s not under water, exactly, though the highest tides creep slowly across abandoned parking lots in some neighborhoods, spilling over the older seawalls. The problem is this is the second time it’s been stricken by a hurricane, and now no one can get the insurance money to rebuild. The same thing has happened to New Orleans and Miami. Boston may be next. Those who can get out, do. Those who can’t, riot. They have a right to be angry. His daughter is pregnant with his first grandchild. My nephew cannot keep his family safe indefinitely, but he’s glad his parents taught him how to grow food.

More years pass, and my nephew turns sixty-five. He proud of his skill as a farmer, especially with the way the rules keep changing. The farm seems to be in Zone 8, these days. He’s got new crops and new weeds. He has friends in southern Maryland who haven’t had a hard frost in two years. Maybe this year they will; Farmer’s Almanac says it’ll be cold. Last year, he and his wife took a trip through New England and let his kids take care of the harvest for once. They stayed at romantic little bed-and-breakfasts and took long walks in the woods, holding hands. There was white, papery birch-bark on the ground, here and there, the stuff takes a long time to rot, but he knew he’d have to go to Canada if he wanted to see one alive. The American white birches are all dead, killed by a changing climate. It’s sad.

Eventually, my nephew becomes a very old man, a spry but somewhat stooped 89-year-old, mostly bald, with great cottony billows of hair spilling out of his ears, his breathing deep and slow and marred by occasional coughs and rumbles. He has lived long enough to see more change than any prior human generation has, and that’s saying something. A lot of the change is environmental, but not all of it. Major technological shifts have reworked the country yet again, and the entire political and economic center of gravity has pulled away from the coasts. He is aware of this upheaval intellectually, but viscerally he is used to the world he lives in. He lives well. He is loved and he is useful. No dramatic disasters have befallen him–the worst-case scenarios have not played out, but mostly he’s just been lucky. Plenty of disasters have happened to other people. My nephew is sympathetic. He writes his Congress-people and gives generously through his church whenever he can. But a lot of good that could have been done decades ago wasn’t.

I saw my nephew tonight. He’s at home now, wrapped in a blue blanket like an animate dumpling, slowly fretting against the swaddling. His wrists and ankles are as thin as my thumbs. He’s too young for baby fat. He doesn’t know what his future holds. And neither, really, do we.

——————–

I wrote the above several years ago and many of my predictions have already come true. My little nephew has indeed learned about birthday cake (I hope he does not yet know about mean people) and has carried treats to the chickens, though he prefers the company of the goats and can imitate their voices. More darkly, Manhattan was hit by a major storm-surge (Superstorm Sandy) and Miami Beach now floods regularly due to sea-level rise. I don’t think my nephew knows it, but the years of his  life thus far have seen consecutive global heat records broken, two successive record-breaking tropical cyclones (Haiyan and Patricia), rumors of “jellyfish seas,” a major climate-related refugee crisis, the possible California Megadrought, and dramatic, unprecedented fires in Canada, the United States, and Indonesia. Among other deeply worrying, and now more recent. developments.

Come on, people, put your backs into it, whatever we make of the future, my nephew will have to live there.


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The Climate and the Contagion

Four red-brown blobby things with a fringe of short hairs around each one. The background is blue. The image is a photo taken by scanning electron microscope of actual coronavirus particles. It looks similar to images that have appeared on the news lately.

Photo by CDC on Unsplash

The new coronavirus is not caused by climate change.

However, some of the circumstances that set the stage for the emergence of the disease are also part of the climate change puzzle, and infectious disease more generally is part of the package of problems caused or made worse by climate change. There are other ways in which the two stories are linked.

Let us explore those links.

The Climate and Corona

Coronavirus is not actually the name of the disease, though anyone who has watched at least one news broadcast in the past month knows what  disease I mean. There is an excellent summary of the outbreak here, but I’m unclear whether the article is going to be updated–it might look very different by the time you read it, as this story is evolving very quickly.

The new disease has been officially named 2019-nCoV or COVID19, but most people continue to refer to it simply as the coronavirus. I will sometimes do the same.

This comic is mostly people talking. Rather than type several paragraphs of text into this box, I invite you to go to https://www.explainxkcd.com/wiki/index.php/2275:_Coronavirus_Name as there is a transcript and description there, as well as a very humorous discussion about the comic's meaning.

From XKCD, by Randall Monroe, https://xkcd.com/2275/

I’ve seen posts on social media to the effect that coronavirus has killed very few people in comparison to, say, poverty, and the only reason it’s been getting so much attention is that it can kill rich people. Such criticism is fair in a general way, but it misses a crucial point; coronavirus has killed very few people yet, but if infection gets close to universal (and it could), the death toll will be in the millions, and most of those lost will be among society’s most vulnerable–the poor, the elderly, and the already ill.

The faultlines of vulnerability  and bias in our society are going to be very much on display.

Causative Links

While COVID19 itself appears not to be caused by climate change (the virus appears to have jumped into our species from animals held at an open-air market), other, equally dangerous, diseases do have a strong link, or could have one.

First, there are diseases, such as malaria, that are spread by animals that require warm temperatures. A warming Earth means those diseases can spread farther and have longer seasons. There is also some evidence that influenza, which normally prefers cold weather, may (counter-intuitively) become more of a problem as the climate warms. There are also long-frozen viruses coming out of permafrost that could conceivably start finding hosts. And as animals change their ranges in response to the changing climate, some could come into contact with humans who haven’t before, potentially giving us diseases we don’t have immunity to.

New diseases don’t usually kick off made-for -Hollywood disasters, and coronavirus is unlikely to do so. What it is likely to do is cause a lot of pain and suffering world-wide and be a major and expensive pain in the neck for possibly every country on the planet. And since climate change is likely to increase the frequency of new diseases, we’re seeing a preview of the future, unless we do something to change our trajectory.

Interactions

One major way that humans pick up new disease from animals is by moving into wild places humans don’t normally go–a situation that’s becoming ever more common as humanity continues to press outward, logging, poaching, and developing previously wild lands. Once a disease makes a jump into our species, the chance of it spreading worldwide quickly is very high, thanks to frequent intercontinental air travel. If humanity used less in the way of resources–as we will have to, without fossil fuel–there would be less logging, less poaching, and less air travel. There would also be less risk of global pandemic.

There is a wonderful book called Spillover, by David Quammen, that explores these and other ideas and presents a thorough introduction to how diseases spread into our species. I recommend reading it in light of current events.

Complications

Coronavirus (and the policies designed to stop it) are causing a measurable reduction in greenhouse gas emissions–when economies slow, so do emission rates. It is tempting to secretly cheer for the disease. I don’t think such cheering is as immoral as it sounds, since cheering alone can’t have any effect on the progress of the disease, but coronavirus is not any kind of solution. First, the change is temporary, and China, for one, has a habit of increasing economic output after a slow-down to make up for lost. Second, the immediate crisis of the disease is likely to distract from efforts to curb emissions, even though climate change ultimately stands to kill more people.

Take-aways?

The new coronavirus could present us with an opportunity to see what it looks like when the world takes a crisis seriously and responds together–and we could take that example and apply its lessons to climate change knowing that public health, like everything else, is going to get harder to look after the worse we allow climate change to get.

Or, we could use the threat of coronavirus as an excuse to put climate even more firmly on the back burner and then simply get used to another level of disaster and suffering, recommitting ourselves to complacency.

We have a choice to make.


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Considering Packaging

I think packaging is bad. Buying products in bulk using reusable containers (cloth or glass, ideally) is much better. Recyclable packaging is better than non-recyclable, but not as good as no packaging at all, and not really OK. When I can’t avoid buying a package, I feel guilty. When my husband doesn’t avoid buying a package, I feel angry.

I’m not unusual in any of this. Plenty of environmentalists think and feel as I do.

But are we right?

Questioning Packaging

I don’t doubt that packaging carries an environmental cost. Most things do, after all, and many resource conservation efforts are organizing around reducing packaging, packaging waste, and litter (much of which is discarded packaging). I don’t doubt the rightness of such efforts.

But consider proportion and context.

Too many environmentalist life-style changes are the equivalent of picking up pennies from the sidewalk—sure, go ahead and do it, but don’t expect much from the exercise. Yes, pennies add up to dollars and dollars add up to wealth, but anybody who expects to earn a living by picking up dropped pennies is deluding themselves. Anyone who expects to save the planet one teeny-tiny bit at a time is similarly delusional. Some things just aren’t worth irritating one’s husband over—other things very much are.

In which category does packaging fall?

To ask about the importance of packaging, though, it’s necessary to rephrase the question. For one thing, “packaging” is not just one thing but a whole flock of products made of differing materials, for differing reasons, and by differing production methods. It took me a whole extra week to figure out how to ask my question so as to be able to find an answer—the key is to look at the substance, not the product at all.

What are the carbon footprints and environmental impacts of small amounts (a pound, say) of the various materials commonly used in packaging? How do these footprints compare with other aspects of a household carbon footprint, such as burning a gallon of gas?

About Plastics

Plastics are a group of substances. I discussed them in a previous post, and the important thing to remember is that what is true of one plastic is not necessarily true of another. Some are a recyclable, some are not. Most cannot biodegrade, but some can, at least under very specific circumstances. Most plastics are made from petroleum, but some are not. Perhaps surprisingly, whether a plastic is made from plants has nothing to do with whether it’s biodegradable; what matters is the chemistry of the product, and the same polymers can be assembled from multiple kinds of oil.

I have not attempted to look up the environmental impact of every single kind of plastic there is, nor have I tried to look up all the kinds regularly used in packaging. Instead, I used search terms such as “the carbon footprint of plastic,” and came up with a few specifics and some generalities that should be roughly applicable to most, if not all plastics.

The important thing to remember is plastics generate questions that have no simple answers. More on that shortly.

The Carbon Footprint of Plastics

According to one study, in 2015 the greenhouse gas emissions from all plastics worldwide, from cradle to grave and including transportation, was almost 1.8 billion metric tons of carbon dioxide equivalent. Not all of that plastic is packaging, and while it’s a good guess that much of it is, I’m not really sure. The article didn’t say. The article also didn’t put that number in perspective–is 1.8 billion a big chunk of total emissions, or a small one? You’d think it would be easy, in the information age, to just look up humanity’s carbon footprint for a given year, especially since it’s easy to find out how much emissions grow or shrink from year to year, or how the footprint of one country compares to that of another. But nope, that information is buried somewhere.

It’s another example of the societal innumeracy I was talking about last week.

But the authors of the article seemed to think 1.8 billion is cause for concern and that plastics are an area that deserves specific attention in the fight against climate change.

Another source looks at plastic bottles and helpfully explains the following:

The manufacture of one pound of PET (polyethylene terephthalate) plastic can produce up to three pounds of carbon dioxide. Processing plastic resins and transporting plastic bottles contribute to a bottle’s carbon footprint in a major way. Estimates show that one 500-milliliter plastic bottle of water has a total carbon footprint equal to 82.8 grams of carbon dioxide.

Again, that’s hard to put in perspective, but since a gallon of gasoline burned produces 20 pounds of carbon dioxide, and one gram is 0.00220462 of a pound, it seems about 109 plastic bottles equal one gallon of gas, footprint-wise. 109 bottles is about a two-week supply for someone who drinks mostly bottled water or soda.

So, yeah, if you drive to the store for a load of groceries, the carbon footprint of your drive will likely be higher than the footprint of the plastic packaging, but it might be close. And if you bike to go shopping in order to reduce your emissions, as I do, cutting back on plastic packaging seems a quite reasonable next step.

But….

There is always a but, and the but of avoiding plastic is that the alternative is sometimes worse. It’s hard to be sure, first because the analysis has to include many factors, and in part because sources of information often have their own motives.

For example, the Coca-Cola Bottling Company (which sells both plastic and glass bottles as well as aluminum cans) reports that glass bottles have been gaining market share against plastic lately, but cautions that glass is not always superior environmentally. Their argument is that it takes less energy to make a plastic bottle than a glass one, and that as long as both are recycled, the problem of plastic in the environment is irrelevant. We’ll get back to the issue of recycling, but Coca-Cola’s analysis may be correct as far as it goes. And if it does take less energy to make a plastic bottle, it probably takes less money, too–so the company has a financial incentive to reposition plastic as a low-carbon option, whether or not it is one.

Financial incentive is not proof of nefariousness, but it’s reason to be suspicious. It’s reason to ask how the carbon footprint of plastic compares to glass after manufacture, in transportation and disposal and so forth–notice the article didn’t say.

But, But….

But there is food for thought out there. For example, plastic packaging on vegetables–which I’ve always viewed as pointless–turns out to increase the shelf-life of such vegetables and thus increase the chance that they will sell. Food waste has a huge carbon footprint, and while vegetables spoiling on grocer’s shelves represent only a fraction of that waste, the thin film of plastic on a cucumber is only a very tiny amount of packaging. I lean towards rejecting the plastic wrap anyway, but without the certainty I used to have.

Then, too, plastic is much lighter than glass, lighter than aluminum, and often slightly lighter than cardboard, meaning that plastic packaging requires less energy to transport than packaging made from its competitors does. Less energy means lower carbon footprint. Again, certainty lessens.

And there are other applications where plastic definitely has a much lower footprint than its alternatives, and customer resistance to plastic is actually a barrier to a company lowering its footprint. As ever, knee-jerk reactions prove counter-productive. There is no alternative to learning and thinking.

But, But, But….

Carbon emissions are not the only form of environmental impact around, and plastic pollution is now a major problem. All other packaging materials, if dropped in the ocean, either biodegrade or eventually turn into sand of one kind or another. Only plastic stays plastic forever.

In some cases, it might be necessary to pick one’s poison.

Cardboard and Paper

Corrugated cardboard has a footprint in carbon dioxide equivalent about equal to half it’s own weight. That is, if you’re looking at a pound of cardboard, you’re also looking at half a pound of carbon dioxide equivalent. So, 40 pounds of cardboard equals a gallon of gas–given that you need a lot of cardboard to get 40 pounds, we’re getting into penny-territory here, something that matters a lot in aggregate but not so much otherwise.

There are other kinds of cardboard and other paper products used in packaging, and except for those laminated with plastic or foil, most are likely similarly low-carbon.

It’s worth noting that most cardboard packaging is removed before products hit the shelves; almost everything–including items sold in bulk, naked on shelves–arrives at stores in big cardboard boxes. I’ve worked in grocery stores, and breaking down boxes for disposal is a common activity. Hopefully, they are recycled. I was never quite clear on whether ours were–they did go into a different compactor from the rest of the store’s trash. But the point is that there is a lot more cardboard associated with your groceries than you can see. But because consumers have no direct contact with this cardboard, it doesn’t fall under the heading of consumer lifestyle choice. If reducing cardboard use is a worthy goal (and it might not be, since complications abound), we need to lean on suppliers to meet that goal, rather than attempting to meet it ourselves.

Glass

According to one source, glass that has not been recycled has a carbon footprint 8.4 times its own weight. Recycled glass has a footprint 1.4 times its own weight. So how much of the glass we buy is recycled and how much is not? I don’t know–it’s most likely a mix.

A glass bottle weighs, on average, eight ounces, so two bottles per pound. I don’t know how big an average glass bottle is, but let’s say that you’re buying both beer and wine in variously-sized glass bottles, and so your personal average bottle weight happens to also land on eight ounces per. So if you buy 28 bottles, you’ll have about 14 pounds of bottle glass. If those bottles are made from all-recycled glass, that’s 20 pounds of associated carbon dioxide equivalent, the same amount you’d get from burning that gallon of gas.

If those bottles are made entirely of never-recycled glass, you’ve got 117.6 pounds of carbon dioxide equivalent on your hands.

Like I said, it’s probably a mix.

Metal

Metal, in packaging, is almost exclusively aluminum nowadays. I spent the better part of an hour fighting with figures provided by one source on aluminum before I discovered the document’s decimal points had gone screwy–a good example of why looking up this type of information can be tricky (another reason is that different assessments may go by different rules and turn up numbers that shouldn’t be compared). On a different source, I found recycled aluminum listed as having a carbon footprint twice its own weight (one pound of aluminum represents two pounds of carbon dioxide equivalent) and unrecycled aluminum listed as having a footprint 12 times its own weight.The big difference reflects the fact that mining and processing aluminum ore (bauxite) requires a huge amount of energy–bauxite mining is reportedly terrible in other respects, too.

In practice, aluminum products like cans are likely a mix of recycled and new metal. Since I don’t know what the mix is, I don’t know what the footprint  of an aluminum can or an aluminum foil wrapper might be. If the mix is 50/50 (as implied but not stated by the source with the screwy decimals which I’m not going to site) the footprint should be seven times the weight of the metal. That’s a start.

So, if one pound of aluminum corresponds to seven pounds of carbon dioxide equivalent, how many aluminum cans make up a pound? Answer: 31 cans. Sometimes information is easy to find, for a change.

That means roughly 93 aluminum cans, or 15 six-packs and three singles, have a carbon footprint equal to burning a gallon of gas if my guess about the recycled content is right.

So, What Do I Buy?

I did find one source that list various types of drinks container in order from best to worse for the environment. The same source also lists carbon footprints for each, but you’ll notice I’ve done this post the hard way by looking up each material in a different source–believe it or not that wasn’t an oversight. I wanted to be able to see if discrepancies emerged between the various sources. It was a form of quick-and-dirty fact-check, and that is how I noticed there was a problem with the source with the wacky decimal places.

I can’t directly check my numbers against this last helpful source, though, partly because it lists carbon footprints per bottle whereas my numbers are by the pound, and partly because it gives low, medium, and high estimates and they diverge wildly (the high estimate for single-use plastic is over ten times the low estimate). This raises the question–are my numbers the result of high, low, or medium estimates?

This last article does a good job of covering both carbon footprints under various scenarios and other environmental impacts, such as pollution. I recommend reading it.

An important take-away is that the environmental impact of various types of packaging depends in part on where you live because recycling options, reuse options, and the energy grid itself all vary. That’s why I’m not reproducing their best-to-worst list (sorry); every entry except “no container” has the caveat, “depending on country.”

So, Does Packaging Matter?

Short answer? Yes, but probably not as much as I thought it did.

In general, for a large shopping trip with most items packaged in something or other, packaging may add the equivalent of a gallon or so of gas to the trip. That’s not nothing, but it’s likely a relatively small part of the household footprint.

Which type of packaging is better is a difficult call, especially since plastic has a low footprint but a terrible environmental impact for other reasons (plastic is almost never closed-loop recycled, either; recycled plastic still ends up in a landfill or the ocean, it just takes a detour through being a carpet or something on the way). There are other complications, too. For example, glass seems like a great option because it can be sterilized and reused, but it almost never is. Individual companies can vary a lot, too. For example, the Cliff Bar company is carbon neutral and is a leader in sustainable industry, so while its wrappers clutter up our house and drive my husband to distraction (I forget to throw them out), they might not count towards our footprint the same way an apparently similar wrapper from a less-enlightened company would.

Practically speaking, there are two choices for a household wishing to reduce its packaging-related footprint: research each product and its packaging individually; or consider all packaging to be roughly equivalent and minimize its total weight.

The latter approach, while definitely quick and dirty, should lead to impact reduction in most cases and has the advantage of being doable.

So:

  1. First, reduce total weight of packaging so far as can be done without making yourself crazy or alienating your spouse.
  2. Where possible, choose recyclable options over those that are not recyclable.
  3. Where possible, choose glass over even recyclable plastic.
  4. Where possible, support environmentally and socially responsible companies, not those that aren’t.

And don’t forget to vote for climate hawks, because that’s really where we’re going to win this thing, not in arguments over cracker boxes.

 


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Hot Little Number

A lot of people—perhaps most—are functionally innumerate.

Innumeracy sounds like it ought to be the mathematical equivalent of illiteracy, and it is something like that, and yet it is also different. And yes, this has to do with climate change.

Illiteracy is primarily a problem of knowledge—an illiterate person doesn’t know enough about the written language to understand it. It’s possible to be innumerate in that sense, and that kind of numeracy can lag far behind literacy for some. For example, I am so fully literate that I make my living as a writer and an editor, and yet I don’t actually know how big a million is. I could count to ten thousand, if I wanted to, but I couldn’t count to a million. I don’t know how.

But there is another form of innumeracy that has less to do with knowledge and more to do with the ability to use mathematical logic. For example, if I say “300 people died of food poisoning this year,” that doesn’t tell you anything. Am I talking about an outbreak in a small town, or am I talking about the entire United States? How many people die of food poisoning in a typical year—is 300 more or fewer than usual? Only with context does this number, 300, tell a meaningful story.

Knowing where to look for that context and how to interpret that context is the beginning of statistical literacy, a related but different issue, but if you don’t know some kind of context is necessary, then you might as well not know the number 300, either.

That’s functional innumeracy.

The reason this matters for climate change is that again and again in the course of researching for this blog I find numbers presented to the public without their context, or with inadequate context.

  • Product A. requires more energy to produce than Product B.–does that include manufacture only, or does it also include the energy required for acquiring raw materials?
  • A certain university boasts that it has reduced its carbon emissions by a certain number of tons per year—but what is the new carbon footprint, and is it bigger or smaller than typical for similar schools?
  • Nationally, a certain substance is responsible for a certain number of tons of carbon dioxide equivalent—but is that number big or small compared to the footprint of the country as a whole?

I realize it’s a little difficult to make sense of hypothetical examples, but I’m trying to keep this post quick and to the point, without getting bogged down with real-life detail.

When I see numbers presented without context, I wonder whether the people presenting those numbers don’t realize the context is necessary, or if they simply aren’t as interested in climate action as they appear to be? Indeed, careful attention to which context is missing often reveals something that could be to the advantage of the entity releasing the numbers—but whether the oversight was actually deliberate, I’m not in a position to say.

I can confidently assert, though, that the fact context is not given means that the public doesn’t demand it. And that means there are important questions, questions that could make a great deal of difference to how we attack climate change, that we’re not asking. It also means that we’re leaving ourselves vulnerable to people who sound good but don’t have the facts on their side.

Innumeracy is unlike illiteracy in that the latter can really only be fixed by education. You can’t will yourself to read if you don’t know how. But if you understand numbers in a general way—and most of us do—you can will yourself to think more carefully about them, and on the basis of careful thought you can ask more questions.

Sometimes that’s all that needs to happen, to begin with—ask a couple of good questions.

And then seek answers.


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Roofs for Heaven

So, our roof sprung a leak.

I realize some might question my sharing this small bit of personal woe, but really, what homeowners don’t have an issue now any then? In fact, I’m told that roofs need to be replaced routinely–it’s an expected hassle, especially for some of the shorter-lived roof types. That means you, too, might be in the market for a new roof, and if you’re not now, (if you’re lucky enough to own a home) you will be someday in the future.

So what kind of a roof do we want?

The thing is that roof-shopping is an opportunity, a chance to make decisions about some small corner of the built environment instead of simply accepting it as a given. What sort of roof do I want? Can I have one that’s different? That’s especially mine? That better suits my tastes and values and generally makes me happy to live beneath?

Can, in other words, a roof be a response to the challenge and crisis of climate change?

Yes, it can.

Roof-Related Issues

First, let’s take a look at how roofs are related to climate change. In my reading, I’ve identified three broad categories of relevance: roofs have carbon footprints, so it’s possible to choose a roofing type with a small one; roofs have an impact on the energy use of the house; and some roofs have additional tricks, such as generating renewable electricity.

All of these together, plus such practical matters as cost, become part of the picture for making a final choice.

The Roof’s Footprint

Roofs, like everything else, have a carbon footprint. One way for a homeowner to respond to the climate crisis is to get a roof with a smaller footprint. I was able to find a study that did compare the carbon footprints of various roofing types, at least in Australia, but unfortunately it did not include asphalt shingle, which is the simplest and least-expensive in our area.

The study compared typical residential roofs of sheet metal, clay tile, and concrete tile, including in each case the wooden frame beneath (though not, apparently, insulation). The analysis looked at both greenhouse emissions and embodied energy for each from cradle to grave and found out that the footprint of metal roofing can differ radically depending on whether it is recycled afterwards. The abstract of the paper (reading the full text would require money I don’t have) did not include all of the relevant numbers, so I had to do some math. “CO2e-” means carbon dioxide equivalent, recognizing that there are other greenhouse gasses and their warming potential varies. CO2e- is a way to quantify and express warming potential as a single figure regardless of which greenhouse gasses in what relative quantities are involved.

It’s also not clear from the abstract how much of each roofing material was involved–obviously, larger roofs would have bigger numbers–but the roof in the analysis was the same size in each case. “T” presumably stands for metric tonne, which is somewhat larger than the American ton.

  • Clay tile has a carbon footprint of 4.4 t of CO2e-.
  • Sheet-metal roofing that is not recycled has a carbon footprint of 9.85 t of CO2e-.
  • The carbon footprint of concrete tile wasn’t given, but is intermediate.
  • Sheet metal roofing that is recycled “can obtain significant carbon and embodied energy saving benefits (i.e. 71–73%) compared to clay tile or concrete roof covers,” a grammatically ambiguous statement that seems to suggest the following:
    • Metal roofs, if recycled, have a carbon footprint of 1.27 t of CO2e-
    • Concrete tile has a carbon footprint of 4.7 t CO2e-

So:

  • Metal, if later recycled = 1.27
  • Clay = 4.4
  • Concrete = 4.7
  • Metal, if not later recycled, = 9.85

Curiously, concrete tile, not never-recycled metal, has the highest embodied energy.

So, what about other materials? Unfortunately, figures from different analyses aren’t directly comparable, since analyzing carbon footprints requires making a lot of arbitrary decisions about what to include and what not to include–and each person who does such an analysis ends up making those decisions differently. So I can’t combine results from multiple studies. Anyway, I wasn’t able to find life-cycle analyses of other roofing materials.

I did find an American analysis of the carbon footprints of disposing of various construction materials, including asphalt shingles, and the article did comment on the footprint of construction. Curiously, shingles made with a core of fiberglass felt have a lower footprint than those made of more natural-seeming paper felt, since paper absorbs water and must be dried, a process that takes energy. The fiberglass variety are already far more common.

Another surprise was that incinerating the shingles lowers the footprint of disposal because they can replace other fuels for energy generation, including fuels that have more greenhouse gas emission for the same amount of energy–shingles can’t be incinerated in most facilities because of “impurities” (I’m guessing this means air-quality concerns?) but are accepted as fuel for cement kilns in Europe. Asphalt shingles can also be melted down and added to the asphalt mixes used in roadways, which reduces the total amount of asphalt used and thus lowers emissions related to sourcing the material. Asphalt shingles can, in theory, be recycled into new asphalt shingles, but it’s technically difficult and nobody is doing it. The shingles can’t be composted. None of that is very useful for a homeowner, though, especially as I don’t have access to a European cement kiln.

And I wasn’t able to compare the footprint of asphalt shingles to that of metal roofing.

The Roof’s Role in the House’s Footprint

What type of roof a house has can alter the energy use (and thus the carbon footprint) of the house as a whole. For example, a white roof reflects heat and keeps the house cooler, reducing the temptation to use the air conditioner. A black roof absorbs heat and keeps the house warmer, reducing the need for heating in winter. Which one is better depends on the local climate where the house sits and whether the occupants tolerate cold or heat better. There may, in the future, be coatings available that will darken or lighten in response to temperature, but as yet we must pick a color.

Different materials also vary in their ability to conduct heat into the house, so asphalt shingles will warm a house more than a metal roof of the same color–both because asphalt absorbs a lot of heat and because asphalt roofs are designed to transfer as much heat as possible from the shingles to the house beneath, since otherwise the shingles get too hot and are damaged by heat.

A roof with excellent insulating capacity will keep the house temperature from varying as much, an advantage in both hot and cold weather. The R-value (insulating ability) of a whole roof typically depends largely on a layer of insulation, because the roofing surface tends to have a low R-value no matter what it’s made of, but they do vary, so a material with a higher R-value is better, all else being equal. Asphalt shingle is .44 and wooden shingle is .97. I wasn’t able to get a figure for metal roofing, but it is similar to that of asphalt.

Roofs with Benefits

There are roofs that do more than simply cover the top of the house.

Green roofs, that is roofs designed to support living plants, reduce local air pollution, reduce storm-water run-off, provide animal habitat (depending on what’s planted up there), and can even grow food (if the roof is accessible enough to harvest). They also sequester carbon, although the chance of that carbon remaining sequestered very long is slim–most have to be replaced after about 40 years.

Solar roofs incorporate solar panels and generate electricity.

And, while it’s a bit off-topic for us here, flat roofs surfaced in gravel provide nesting habitat for certain birds (nighthawks, for example).

Roofing Materials

It’s no good just asking what roofing material is “better for the climate” in a vague way. To make a decision, we have to know what kinds of benefits we’re talking about. Now, we do know, so we can get on with exploring specific materials.

Asphalt Shingle

Asphalt shingles are made out of sheets of felt (either paper-based or, more commonly, fiberglass) that have been soaked in a thick type of asphalt and sprinkled with coarse sand. They are popular because they are cheap and, in the short term, sturdy (though quality can vary a lot). Unfortunately, their R-value is low, they conduct a lot of heat into the house, and they don’t last very long. Most must be replaced about every 20 years, meaning that however large their carbon footprint is, a sixty-year-old house roofed in asphalt has three such footprints, not one.

Metal

Metal roofs are moderate in cost (higher than asphalt but lower than some other options) and relatively long-lasting, on the order of 60 years. Their R-value is low, but they conduct very little heat into the house, especially if given a heat-reflective coating. If the metal will be recycled at the end of their service, their total carbon footprint is quite low. They resist most kinds of damage very well, don’t burn (important, as climate change makes wildfires more frequent!), and don’t support the growth of moss or algae, though they can be dented by hail. Many different styles are available–metal roofs can be made to look like several other materials–but do have one aesthetic disadvantage; rain falling on them is very noisy.

Wood Shingles

Wooden shingles are carbon neutral, or close to it (processing and transportation surely involve some emissions), can be made with reclaimed wood from other buildings, and unlike almost all other options, they can be composted upon retirement. The price is only a little higher than asphalt shingle. While at first consideration they seem excellent, I have noticed that even buildings with wood shingle siding almost never have wood shingle roofs. I’m not sure I’ve ever seen a wood shingle roof, come to think of it. Why not?

Wood shingle is actually not recommended from an environmental perspective, at least not by people who don’t sell wood shingle. The problem is two-fold. First, while they can last 30 years under good conditions, wood shingles are vulnerable to rot, and many don’t last even as long as asphalt shingles do–that makes them less economical and increases their environmental impact. Perhaps more importantly, they are relatively dark in color, so they absorb heat. I assume they could be painted, but at the cost of much of their aesthetic value. They are also less fire-resistant than most other roofing types.

Green Roofs

Green roofs have all the advantages of a garden, plus they’re great at keeping the house cool. Unfortunately, the weight of the soil and water means that not all buildings can support these roofs. Installation is also expensive, though not necessarily more so than higher-end forms of traditional roofing.

Green roof designs are categorized by soil depth (and therefore what kinds of plants can grow on them) and by how much maintenance, including irrigation, they need. The categories are labeled “intensive,” “semi-intensive,” and “extensive.” It is possible to have a roof that is only partially covered by a garden and is otherwise more traditional.

Solar Roofs

Solar roofs involve tiles that are each little solar panels. I’m not sure what their virtues as roofing are, and they are more expensive that traditional solar panels; their primary advantage is that they don’t look like solar panels. It’s a moot point for my husband and I anyway, as we live in a forest.

Passive solar energy, in which water is heated in the roof, might also count as a “solar roof,” but is again rendered moot for us by trees.

Other Roofs

There are other roofing options, such as slate, rubber (made to look like slate), concrete tiles, clay tiles, and good-old-fashioned thatch. I love the idea of thatch, and I’ve heard it performs very well. If gathered locally, its carbon footprint could be virtually zero. However, dry thatch likes to catch on fire, and the chance of our finding a qualified thatcher in Maryland is just about nil. The other options are either expensive or hard to find or both, and also easily damaged by hail or other impacts (perhaps not the best thing as climate change makes extreme weather more likely).

That being said, slate has a very low carbon footprint and is reputed to be environmentally excellent, according to multiple sources, most of which sell slate. Clay and concrete have moderate carbon footprints, as already noted. I have not found figures for the other “others.”

The View From (or of) the Roof

Since it doesn’t look like I can have thatch or a green roof, I’ll be pushing for metal. If we end up priced out of that, white-painted asphalt shingle will do, though paint doesn’t stick to shingle very well. Metal is much easier to make white, and I like the fact that it lasts much longer.

Our area has hot summers and cool, but not cold, winters. We are also prone to wind–in the decade or so I’ve been here, we’ve had to cope with hurricanes, nor’easters, a derecho, a tornado, and frequent blustery days (it’s too windy to bike for several days in any typical week). We therefore need a roof that resists wind, rain, and stuff falling on the roof (such as tree branches) and that can keep our house as cool as possible in the summer. We do not need help keeping the house warm in the winter, especially since we heat with sustainably harvested wood, not with fossil fuel. Given our forested lot, solar shingles don’t make sense, especially since we buy renewably-sourced electricity anyway. And cost is a consideration because are not independently wealthy.

Your considerations, and thus your conclusions, may differ.