Just for a little context, note that I wrote this BEFORE Hurricanes Helene and Milton.  Truly leave the rails, indeed.  Do you want more of that?  How about those floods in Spain?

Looking at greenhouse gas emissions, and how the weather has lately started to truly leave the rails, and how various temperature metrics are now solidly up compared to 20, 40, or 60 years ago, we have got to get more serious about reducing those emissions in all ways. It would have been nicer to start back around 1990, which it first became clear at least to me that we were indisputably changing things (around then was when we noticed that the CO2 maximum in the Keeling Curve started coming earlier in the year, because it was overall warmer enough for photosynthesis to start earlier), but oh well.

We were pretty happy to toss around target dates for “zero” emissions 10, 15, or 20 years ago, but now we’re a lot closer to those dates. For example, 40% reduction in 6 years (2030), or “net zero” in 26 years (2050). Some of these goals use 1990 as a baseline, but what people forget is that US emissions went up quite a lot after 1990, peaking in 2005 and then again in 2007. The 2007 peak was 6.13 billion tons of CO2, in 2022 this was reduced to 5.06 billion tons. That’s a 17.5% reduction, but over 15 years that’s a cumulative rate of only 1.3% per year. We obtained most of this reduction in the electrical power industry. 

A 40% reduction by 2030 means our goal for that year is 60% of 1990 emissions, which is just about the same as 60% of current emissions. From here to there, our annual multiplier (compounding downwards) is the sixth root of 0.6, or 0.92. That is, next year’s emissions are 8% lower than this year’s, and the year after that, another 8% cut, year after year. The reduction isn’t necessarily uniform across all sources — if we cut less at transportation, then we must cut more in agriculture or concrete or electrical production, and so on. 8% is a lot, about 4 times more rapid than our cuts since 2007, and because most of that reduction was concentrated in electrical power generation, for most people outside of that industry, the change will feel much more intense.

Or, in 26 years, “net zero”. I’ll call that goal 10% of current emissions, assuming we net that remaining 10% down to zero some other way. The 26th root of 0.1 is 0.915, or an 8.5% reduction per year. I’m using an exponential model because I think that is a reasonable fit for the “easy” cuts coming first, and the hard ones coming later. Sooner is also more important for avoiding even more climate change, and also helps counter our natural tendency to procrastinate. But even if we assume a linear model, 90% reduction in 26 years is 3.5% per year (3.5% of today’s emissions, each year, which results in proportionally much larger reductions in the future.) Part of the reason we favor delay, also, is our tendency to hope for a technology-based solution that will require less cost and less change in our daily lives, and this is not entirely wrong; solar power has become far cheaper, faster, than anyone predicted in the past, but it wasn’t that cheap in the beginning.  But gambling on future magic because change is annoying is a dumb bet.  We might not ever be able to produce giant electric trucks in the volumes needed.  Battery technology or solar cell improvements might stall.  Perhaps (earth-bound) fusion energy generation will never arrive.  There are physical limits (thermodynamics of heat engines, LED light conversion) where we’re already relatively close to the best we can possibly do.

But 8% or 3.5%, those are just numbers.  How does that relate to the real world?  I have some small reference for this, though it is old, and I was young.  I grew up in Florida, in one of 3 adjacent counties (Hillsborough, Pasco, Pinellas) whose population grew by 3% per year for 20 years in a row. This was a lot, but also, it happened. That was adding people (and traffic, and other infrastructure) at 3% per year, year after year.  It was annoying, but we did it, and also, because it made money for the right people, it happened, year after year after year.  And “annoying” is sort of the right way to think of it — it wasn’t like the end of the world, it was just more people, all the time.  As a young teenager, I resented the developers mightily for tearing down our 1/2-mile-in-all-directions citrus grove playground, but as an adult (and one who one-third owns that same house now) not all that change was bad.  In the good old days, groceries were eight miles away; now, it’s a long walk.  In the good old days, it might take the power company 2 or 3 days to schlep a truck out through half a mile of sugar sand after a squirrel cooked itself on our transformer.  In the good old days, we did not even have a fire department, not even a VFD for the first few years (we eventually had to quit burning our own trash after civilization arrived).

So where and what should we be cutting, to hit those targets? From the EPA’s inventory of US greenhouse gas emissions and sinks, we can see that the three largest categories are transportation, industry, and electricity generation. We’ll need steady cuts in all of those sectors to meet our goals, and a lot more than getting rid of plastic straws (which was a lot of noise about a rat-fart amount of plastic).

For electricity, we have a plan of sorts; in the short run we have used less and less coal (mostly replacing it with natural gas), but now we need to deploy, as quickly as possible, more wind and solar with battery backup and improved grids to help send electric power from where we have it to where we need it. It’s important not to get too distracted by the fact that natural gas is not a long-term solution; it’s a big win to replace coal with gas, and we can do that quickly, and until we have adequate storage, having gas turbines available to cover solar and wind gaps means that we have a ready-to-use temporary answer for “wind and solar aren’t always there”. As wind and solar supplies become more abundant, use of gas to fill gaps will become rarer, those plants will become and more and more expensive per generated watt as they sit more idle, and alternatives will become cost-competitive and then gas will be fully retired.  There are also “market adaptations” that need to appear (that will appear) — a property of solar is that it often produces more power than is needed around the middle of the day, so that offered prices on the power/energy market fall to zero and actual prices are very low.  If energy is cheap enough often enough, that improves the economics of storage (literally, buy low, sell high) and if the cost of an idle-at-night factory is low enough, can make daytime production of energy-intensive products cheaper (ammonia, LLM training, something like that).

Conservation is helpful and good and complements cleaning up generation, we can do conservation now and it’s often not hard and often not particularly expensive, but we’ve also already replaced most of our old crappy lightbulbs, and we’ve been improving appliance efficiency for decades. Nuclear is fine if we can get it built. Fusion, if it ever arrives, sure, but will we get anything from fusion in the next ten years? That’s very, very unlikely. There’s a bunch of people who are Overly Excited about thorium-based reactors, but they do have a good story, perhaps it will pan out. But overall, there is a plan, and the possibility of better plans. Part of the reason we have been able to do so well with electricity generation is that its use is not sensitive to how it is generated; if we can connect a source to the grid, we can use it, more or less, and it requires almost zero change in our daily lives unless we work for a power company.

Industry emissions are down somewhat from 1990, but there are hard problems. Two of the largest components of industry’s share are steel mills and clinker production for cement, the binder in concrete. Clinker production is both energy-intensive and because of its chemistry, inherently CO2-emitting. Steel production is also energy-intensive, and historically used coal in blast furnaces. Fortunately, blast furnaces are being replaced with electric arc furnaces., which are not (yet?) zero-carbon, but are still much better. There’s also all sorts of research into ways to reduce CO2 emissions from cement production, and some of that even appears to work. In both cases using less is an option, but it seems darn unlikely that we’ll get anywhere near zeroing out steel and concrete use. This might end up as some of the 10% that remains to be balanced by carbon capture of some sort.

Agriculture isn’t that large a chunk of the pie, but a whole lot of that chunk comes from our dietary choices; meat tends energy-intensive because of the resource costs of animal feed, especially beef and pork (trawled shrimp, lobster and deep sea fish are also not great), and it costs very little to eat less meat, doesn’t require a change to industrial processes, etc.  (I didn’t even say “vegetarian” — just eat less meat, be more thoughtful about frequency, and portion sizes.)

The largest chunk of emissions in this pie, at 28%, is “transportation”. Most of those transportation emissions come from “light duty vehicles”, and the next-largest category is “medium and heavy-duty trucks”. Combined, they total 80% of US transportation emissions, or 22% of total US GHG emissions. The individual gluttony of various billionaires and their private airplanes is a bright shiny object, but vehicles on roads are a much larger problem. It’s also fortunate that aircraft’s share is not that large, because long-haul air travel will be hard to do without energy-dense liquid fuel; we can get rid of some of air travel emissions by replacing shorter flights with more-efficient and more-electric trains, but the long-haul flights are likely to remain in some form — perhaps we’ll use biofuel (it’s expensive, we can only make so much of it). Worldwide, shipping has a larger share than in the US because of ship registration shenanigans and also because we drive unusually much in unusually large cars, but it’s still nowhere near the majority. I haven’t seen a working with-arithmetic explanation for how we’ll replace ship propulsion with non-carbon power, so, ship less, or get used to much slower shipping?

But the biggest part of the US transportation pie by far is road transportation emissions, and we’ve not done a great job at reducing them. Emissions per mile are down somewhat, but not as much as they could be, because many modern passenger vehicles are unnecessarily large. Mileage is definitely up. Carpooling is down. Housing close to employment centers tends expensive, so people are forced to “drive till you qualify”. All of this combines to yield somewhat increased road transportation emissions since 1990. If we are to have any hope of reaching emissions targets by the goal dates, we have to do better, and quickly. Electric cars and trucks are great, but we aren’t buying or selling anywhere near enough of them, it’s not clear that we can produce them at that rate anyway (especially at the resource-hungry sizes popular here in the US), and we can also do other things right now that would complement a transition to electric cars. The average age of a car on the road today is 12 years; if we plan to zero out road transportation emissions by 2050, then the last gasoline-powered car needs to be sold about 10 years from now (another deadline we’re very unlikely to meet).  And no, we don’t grow enough corn to make it work with ethanol, never mind that corn needs fertilizer which is currently produced using natural gas.  We need to do more than just “decarbonizing cars”; that won’t happen fast enough.  We need to drive smaller cars (they burn less gasoline; smaller electric cars stretch natural resource inputs further), drive shorter distances, figure out ways to not drive for some trips.

So, how? Simply talking about the need to change won’t make it happen, in our current system, if someone can save a dollar by selling a larger truck, or driving an extra mile, they will do that. Cars are easy, comfortable, and convenient, and we’ve worked really hard for years to make them that way. Without incentives, meaning taxes and regulatory change, meaning both carrots and sticks, people in general won’t change, and profit-oriented businesses really won’t change.

A carbon tax is one good way to fix this for industry, but individual people hate taxes, so even though things have to change, we must look hard at regulatory fixes that help reduce transportation emissions, partly because they aren’t generally costly (*), and partly because making the regulatory fixes would give people more room to adjust their behavior to carbon taxes.  We should definitely not drag our feet on better regulations and wait for angry tax-driven demand for reform to appear.  (To anchor discussions about “carbon tax”, a $100 tax on a ton of CO2 translates into about a $1 tax on a gallon of gasoline.  So how grumpy will people get if gasoline costs a dollar more?)   (*) Generally costly, meaning, lots of people cannot afford to travel to work. Things will be costly for some industries, though.  Coal mining will vanish, oil drilling should become far less common.  Auto manufacturers that bet their future on monster trucks will have some lean years; this is of course a plain management failure, since our situation is not a surprise and they should have planned for this.

Regulations, we can both add, and remove. Somewhat surprisingly, we (in various states) have regulations that prohibit road use of tiny trucks and cars, but seem to set no particular upper limit on light-vehicle size. This is apparently in the name of “safety”. We weirdly worry that people will choose vehicles that are unsafe for them to drive, but do not care at all whether those vehicles are unsafe for anyone else, we don’t even measure it, and big surprise, pedestrian deaths are way up. We should fix that glitch. One of the reasons automobile companies are so fond of selling us largest-possible trucks and SUVs, is that various pollution and fuel economy regulations are less stringent for “trucks”. We should fix that. For e-assist bicycles, the US currently doesn’t allow them to have four wheels, despite their safe and successful use in Europe. We should fix that, any lower-impact way to move cargo, is good to have as an option. Our states have a hodge-podge of e-bike regulations, they should be normalized.  Golf cart regulations are a similar mess; if it’s not a limited access highway, a golf cart ought to be legal to use there.  On the roads, transit tends to be unattractive because it is stuck in the same traffic as the cars; why would you take the bus, if it isn’t faster than driving? We should fix that; transit needs reserved lanes and tracks and reserved rails, so it can be fast, so people will use it. If people could afford to live closer to where they work, they would have shorter commutes and generally shorter car trips because of population density, and might not even need a car for usual trips (I don’t), and the greater density would also help make transit more cost-effective. So the (zoning) regulations that prohibit greater residential density near jobs and near transit (e.g. commuter rail) need to go.

These are just the rules I happen to know about that get in the way of reducing emissions; there are surely more that I don’t know about, and those also need adjusting. And yes, fixing rules will cause change, that is the whole point of fixing the rules, we are not cutting our carbon emissions anywhere near fast enough.  Demanding that emissions reductions must not change anything significantly means that they will happen more slowly, AND with greater expense.  And understand also, these rule changes generally allow people to change in the direction of lower emissions, they do not require that change.  And they might not work for you, but they probably work for someone else, maybe a lot of someones.

Revised regulations would help power generation, too. Specious objections to windmill installations are ubiquitous; we should focus on what matters, and otherwise prune away the BS. The thorium nuclear power guys seem a little bit like true-believers from where I sit, but they do have a point, there are many, many regulations on nuclear power (for really good reasons) but the regulations are tied to a particular technology and set of risks (it’s an interesting video, worth watching), and make innovation outside that particular technology more difficult. They need adapted regulations, and they need those to come along quickly. Some states and municipalities have random-ass regulations on solar power systems, covering whether they’re allowed to be tied to the electrical grid, what they will (or won’t) be paid, how they can be sited, etc. Every rule is an obstacle, every rule needs to pull its weight. Even complying with reasonable rules imposes a paperwork and design tax, so even good regulations need to be carefully written and well-administered.

The necessary regulatory changes aren’t always reduced regulation of green tech; for example, for e-bikes and other small transportation e-devices, there need to be regulations on battery safety, because right now there aren’t really, and there have been fires, and without safe batteries various governments might, because of legitimate safety concerns, ban them from mass transit or storage in apartment buildings.  That is, to avoid onerous regulation of e-bike use and storage, we instead need regulation of their batteries, to be sure that they use a safe chemistry (safe, practical, battery chemistries already exist, this is just a case of under-regulated businesses cutting safety corners for profits).

A carbon tax can help drive changes in business behavior. We apparently have lower-carbon cement now, ready to buy, but not yet in quantity because it is not cost-competitive with old-style cement. Add a large-enough carbon tax, and then it is, and suddenly the lower-carbon cement will have a (very large) market and will ramp up as fast as modern industry can. A carbon tax will make natural gas a little less competitive as a backup for energy supply glitches, and batteries a little more competitive, and so that backup will shift to batteries more quickly. A carbon tax can also make what coal remains in electrical generation somewhat more expensive than the lower-carbon alternatives (wind, solar, gas, it’s all better than coal.  Coal sucks, above and beyond its worse emissions).  A carbon tax will make blast furnaces a little less competitive, and electric arc steel furnaces a little more, so that will shift.  

One hard, interesting question is how large should a carbon tax be?  One method for determining it is to attempt to estimate the future cost of the climate disaster that results from not reducing emissions, discounted from when that future cost occurs till today, based on some random estimate of future interest rates, blah-blah-blah.  Basically, so many unverifiable yoinked-from-an-orifice parameters that you can come up with any number that you want.  I think it makes more sense to look at what tax it would take to make today’s no/low-carbon alternatives viable competitors at today’s costs, and estimate how many years it would take the alternatives to ramp up to 100% replacement production, and increase the tax up to that level over a period of that many years.  Yes, this is a windfall for the forwarding-thinking people who gambled on the commercial success of various low-carbon industrial processes, is that actually bad?  One problem with a carbon tax, however, is that the tax rate required to make (say) no-carbon concrete be commercially viable, might translate into a substantial increase in gasoline prices, and there will absolutely be some people who lack any alternative other than to pay those taxes.  They may have just spent a lot of money on a gas-guzzling SUV that they need to tow horse trailers up and down a hilly unpaved some-times snowy road they share with quarry trucks (this is not an imaginary example, I know someone who does exactly that, except that their SUV was old and rusty last I saw it).  

To work through what a change-forcing tax might mean, concrete is about 1/7 cement by weight, traditional production creates about an equal weight of CO2, and the cement currently costs around $130 per ton.  Concrete costs $60 to $75 per ton, cement’s contribution to that cost is $130/7 or around $19.  A $65/ton carbon (CO2) tax would make cement cost 50% more, but would only raise the price of concrete by 1/7 of that, or about $10 per ton (13-17% more).  Construction would still use concrete at those prices, maybe a little less of it.  That same $65/ton tax would add more than $0.65 to the cost of a gallon of gasoline or diesel, or 19% of today’s $3.40/gallon totaling $4.05 (the direct tax is about $0.65, but it took energy to produce that gasoline and much of that energy production also created taxed CO2, so the total increase will be more).  Other things will also cost more, depending on the carbon-intensity of their production.  In Europe, actual per-ton carbon taxes range between $0.17 and $132, with a median of $48, so there are people in Europe already living with these sorts of price changes.  But also, for products like gasoline, there’s a range of price-sensitivity; someone who earns more money will grumble a bit, and probably just pay the extra cost, maybe eyeball a smaller truck for their next purchase.  Someone who doesn’t earn so much will need to cut back, either on gasoline, or something else, and their next truck is probably a used truck and the demand for smaller used trucks drives up their prices… — they may be pinched.  It sounds a lot nicer to call it “greater price sensitivity”.  One simple trick that Europe uses to mitigate this problem is a lower GINI coefficient, and we in the US could change taxes and subsidies in general to mitigate the pinch of “greater price sensitivity”.

A carbon tax is not all cost — all that money has to go somewhere, either additional government spending, tax reductions, debt reduction, tax credits, or per-person dividends (like the Alaska Permanent Fund — this is not new or radical, we do it already).  2022 US CO2 net, equivalent, emissions were 5500 million tons; if all of that was taxed at, say, $50 per ton (about the European median) the resulting revenue is 275 billion dollars, or about $1000 per either US citizen or US adult (those populations are similar, in the 250-280 million range). If that money were simply spent as a per-capita dividend, someone who really didn’t want to change what or how much they drove could just use all that money to pay the extra tax-on-gasoline.  Its equivalent is 2000 gallons, or 20,000 miles in the truck with the worst MPG (12mpg EPA, 9mpg measured, call it 10).  But the 9th worst truck could travel 90% further on those same 2000 gallons.

And yes also this is obviously social engineering, the choice to regulate trucks more lightly is social engineering, the choice to tax gasoline so little that revenues don’t even cover road construction and maintenance is social engineering, the choice to only measure “level of service” in intersection design, and not pedestrian convenience or safety, is social engineering, etc.  This is an attempt to engineer a reduction in greenhouse gas emissions, and that will involve change, and because we dragged our feet for so long and did dumb counterproductive stuff like increasing vehicle sizes when we should have been shrinking them, now we need to change much more quickly, in ways that will more often be annoying. If I were the Benevolent Economic Planner, I would plan lots of walking, bicycles and good mass transit within dense cities, and commuter rail to the dense-enough suburbs that could feed it.  That won’t work for everyone — I’d prioritize electric cars for everyone living in random places without other good choices (it would be wrong for me to buy an electric car for myself; I already use a bike for most trips, that car would be put to much better use by a suburban commuter).  Default vehicles ought to be small; I would definitely impose a special tax on extra-large vehicles, and remove bans on smaller vehicles. If people want to move to a place that allows them to reduce their daily driving, that should be a plausible option. Higher-density housing should generally be legal, but especially in cities, especially near transit.  Some of these changes would require other changes (common rules for paying for schools come to mind) and as Benevolent Economic Planner, I’d make those changes, too.

We need to change a bunch of taxes, rules and regulations, and we need to accept the change that will result.  If we pretend that nothing should change and continue to drag our feet, we will get oceans rising even faster, even more strong hurricanes, even more heat waves, even more droughts, more floods, more landslides, and more extreme weather in general.  Some farmland will become desert, some cities will become uneconomic to maintain, or worse, uninhabitable.  It won’t happen overnight, but if we don’t clamp down on emissions very, very quickly, it will surely happen.  And if it doesn’t happen to us, it will happen to our children, and to our grandchildren.