So your planet has global warming. Venus says “Welcome to the club!” CO2 pollution  not only destroys the environment and adds to remediation costs, the traditional air pollution that comes with it shortens your life. While this undoubtedly annoys you as a human being, it could be worse; your planet might not have excess carbon dioxide emissions or pollution because no one wants to be there (hello Mars). Still, it would be great to have a thriving planet without pollution. People could do more things over their longer life.
Pollution like congestion can be thought of as a queueing problem. There is a demand side (production of pollution) and a supply side (the ability (capacity) of the environment to process pollutants). When the production of a pollutant exceeds the ability of the environment to process, the pollutant builds up, e.g. there is more CO2 in the atmosphere because humans produce more CO2 than nature can absorb in the short run. So like traffic in a queue, CO2 in the atmosphere rises. This is a straight-forward physical process.
When the CO2 in the atmosphere rises, the heat of the planet rises with it. This is also a straight-forward physical process, noted by Arrhenius in the 19th century. Now like transport and behavioral systems, environmental systems are complex, so even though the direction is clear, the rate of change is hard to ascertain, and there are many mitigating or exacerbating feedbacks. Still more CO2 emissions means more heat.
Some of that gets absorbed in trees or the ocean, or is not measured, but the temperature will rise. If the rate of human production of excess CO2 falls to zero, the excess CO2 in the atmosphere will eventually be absorbed by nature, the queue will be discharged. But nature will have been changed by the whole process. For as long as we don’t have net zero or net negative carbon emissions, the queue of unabsorbed pollution will continue to lengthen.
There are a number of proffered solutions out there. Pollution is, in principle, a mostly solvable problem, even if no fast-growing planet has, to the best of our knowledge, fully solved it.
This article outlines ways that pollution could be solved. Some of these are dumb, many are good, one is great.
- Capacity [Bio-Engineering] – Perhaps the most obvious, ‘common sense’, solution when demand (pollution) is in excess of supply is to expand capacity. This is what we do with most things if we can. If our house is too small, we make it bigger. If our wallet can’t hold all of our cash and ID cards, we get a bigger one. If the internet is too slow, we add capacity. In roads, this usually means adding lanes to existing roads. Perhaps we could plant more trees to absorb more carbon pollution. Unfortunately, there is not enough space for enough trees to offset the problem. Maybe algae in the oceans, but that sure seems like that would have adverse consequences.
- Capacity [Geo-Engineering] – Besides planting trees, perhaps we could do something faster, typically called geo-engineering, using the power of chemistry to capture CO2 gas or change CO2 gas into something more benign. Wikipedia lists a bunch of inter-related topics:
- Carbon dioxide removal
- Greenhouse gas removal
- Bio-energy with carbon capture and storage
- Carbon sequestration
- Direct air capture
- Ocean fertilization
- Enhanced weathering
- Carbon air capture
The first problem with this set of solutions is that it is potentially expensive. Adding to the ability of the planet to absorb pollution is difficult. Unlike transport, people have only done this kind of geo-engineering speculatively. So there is a huge risk associated with some of these techniques, especially the more speculative ocean fertilization. But you know, “what could go wrong?” For the less expensive methods, the question is whether they can scale to be significant contributors.
- Solar Radiation Management. Just deal with the heat, ignore the carbon. As Wikipedia says: “Solar radiation management (SRM) techniques would seek to reduce sunlight absorbed (ultra-violet, near infra-red and visible). This would be achieved by deflecting sunlight away from the Earth, or by increasing the reflectivity (albedo) of the atmosphere or the Earth’s surface.” This sounds like a terrible idea to me, but if the CO2 is bad only because of the rising heat, it could be an interim solution. Volcanoes have similar effects. The problem is cold summers, and one could easily imagine this going badly for crops (and thus humans). Wikipedia has a series of articles …
The first set of strategies are basically supply side. But pollution problems are caused by a mismatch of supply (ability to absorb) and demand (production). So let’s turn to demand. The main sources of demand are transport, industry, agriculture, and residential, with the electric power sector serving these indirectly.
The basic equation for emissions in the transport sector is given by:
Emissions = Liters/KM x Carbon/Liter x Vehicle KM Traveled.
If cars had better fuel consumption, less emissions per fuel consumed, or traveled less, there would be less emissions. All three of these things can be worked on together.
The first few are technological shifts, the latter will require behavioral change.
- Bio-fuels – If all of our fuel was from recently deceased plant matter, rather than oil (long deceased plant matter), and those plants were replanted, net CO2 from burning fuels would be about zero (assuming the equipment used to harvest and transport the bio-fuels also used bio-fuels, (like turtles, all the way down)). The advantage is that the energy density of liquid fuels is generally better than batteries. The disadvantage is the large amount of area needed for bio-fuels, which will compete with food agriculture for the best farmland. This is likely to be especially important for aviation.
- Controls Better pollution control devices like the catalytic converter for Internal Combustion Engine vehicles have significantly reduced tailpipe emissions of EPA criteria pollutants. Something similar could be done for CO2 emissions. So the same amount of liters would somehow produce fewer tons of carbon. The difficulty here is chemistry. The gasoline is ultimately burned, producing CO2. Perhaps it can be captured and stored, or catalyzed into some other what we know believe to be innocuous byproduct. Arguably this is a supply side method, but I class it as demand side here as the aim is to reduce the amount of CO2 emitted, not improve the capacity to deal with emitted CO2.
- Improve fuel economy in transport. Better fuel economy for Internal Combustion Engine vehicles has significantly reduced fuel use, and thus CO2, and has plenty of generally good side effects for society, like reduced air pollution and less dependence of oil more generally. Increased energy efficiency overall throughout the economy is feasible.
- Electrify the automobile fleet, switch the energy source for automobiles from fossil fuels to electricity powered by renewable sources (e.g. solar and wind and hydro and nuclear) or use fuel cells to transform the number of Liters/KM to zero.
- Reduce (or end) automobile use. This works on the third part of the equation. Transport is about 1/3 of CO2 pollution, plus or minus. My earlier post “21 Strategies to Solve Congestion“, (which this not-coincidentally resembles), outlines how to reduce automobile demand, which is a large or the largest source of CO2 pollution. So long as cars continue to rely on the Internal Combustion Engine (in some form for a few more decades yet), reducing automobile demand and gasoline consumption will be critical to reducing CO2. There are many reasons to reduce automobile use, pollution among them. It turns out that biking is more efficient than driving. It turns out, more surprisingly, that eBikes are more efficient than bikes (after netting out the extra energy for the extra food for the extra calories burned biking).
The same basic logic applies outside the transport sector. Emissions depends on energy consumption, carbon content, and activity.
- Conserve. Reduce electricity and natural gas consumption at home and work. Use LED light bulbs. Insulate your buildings. As Jimmy Carter suggested, put on a sweater and set the thermostat cooler in the winter. Strip naked and set the thermostat higher in the summer (though he didn’t say it, he may have thought it). Recycle. There are a thousand or more ways to reduce energy consumption.
- Make production processes more energy efficient. This is related to conservation, in that it reduces consumption, but at a much bigger and holistic scale, and examines the process by which outcomes are achieved.
- Use Renewable Energy in the Electricity Sector. Electricity is about 1/3 of greenhouse gas emissions in the US. Transformation from burning coal is well underway, and adoption of renewable energy sources like solar, wind, and hydro power, among others, are the best way to get this sector down to zero net CO2 emissions over the coming decades. There is a large amount of fixed capacity (sunk costs) out there now, so the transition will take some time.
- Reduce industrial energy demand by closing industry – Industry is about 1/5 of CO2 pollution. Perhaps intuitively, if we shut down polluting industries, we reduce pollution. To the extent we want the thing the industry intends to pollute (aside from the pollution), this might be problematic. If we want it closed, but want the goods, the factory will pop up elsewhere with fewer environmental strictures.
- Exhortion – Tell people they shouldn’t pollute because it is bad for themselves, or society, or will condemn them in perpetuity to an unpleasant afterlife. Guilt can get you a little bit of benefit, but as evidenced by the state of the world, can only go so far. This is really a means to one of the other ways of actually reducing pollution.
- Rationing – Give people and firms pollution credits, the right to emit a certain amount of CO2 per year. Reduce that credit annually. Allow them to trade credits for money. If it were cost effective to reduce pollution, they would do so to sell credits. If it were not, they could buy credits. When people talk about cap and trade, that is a form of rationing.
- Pricing – Charge people and firms for the amount of pollution they generate and they will generate less pollution.
- How do polluters reduce pollution? This is the best part. Each individual or firm decides for themselves whether or how to consume or pollute less, what production processes to change, when to substitute clean power for dirty. With pricing, polluters will see the air, which is now treated as an unregulated commons as a valuable resource, and if they increase throughput per unit of carbon, they will save money. They will try to be more efficient about managing the use of the existing clean air.
- Isn’t this another tax? This is the second best part. It raises money by discouraging people from doing something that we don’t want them to do. Other high taxes on things that we do want them to do (like work) can be lowered. Done properly, this is revenue neutral.
- Can this work? This is the third best part. There are many proposed strategies to implement pricing. Obviously this has been politically difficult, or it would already be widespread. Carbon taxes are the simplest intervention, and we already do this in some places (12% of the world’s Carbon is already taxed). Since it is assessed for industries rather than on individuals, it has a low cost of collection. For instance rather than metering each car, petroleum from refineries or fuel wholesalers can be taxed. This accelerates the uptake of electric vehicles, which should on the net be a good thing.
There are undoubtedly some other solutions out there not discussed here, and lots of details overlooked.
As John Lennon might have sung in the 1970s:
Pollution is over, if you want it.
Pricing is the answer and you know that for sure
Pricing is a flower
You got to let it, you gotta let it grow
- This post is basically a rewrite of my popular post about a different externality: congestion: “21 Strategies to Solve Congestion“. Perhaps we might call this `CO2gestion’.
- Yes, I know some people don’t accept CO2 as “pollution” and prefer “emissions.” Since it is above the ability of the environment to process in the short term, it imposes harmful or dangerous effects, and so it is pollution, even if it is a natural product. All pollutants are fine in small enough amounts, and everything is horrible in too great amounts.