"HOW IS THAT RIDICULOUS?"

My current favourite conservative meme is a video showing Joe Rogan proposing to his guest, "You have people like Bill Gates saying that ‘planting trees to deal with carbon is ridiculous, that’s a ridiculous way to do it…’ How is that ridiculous? They literally turn CO₂ into oxygen. It is their food."

There’s so much to love about this, but we can just stick with the planting of trees and carbon offsetting and don’t need to get into the politics around Bill Gates or how ‘20s Republicans are just ‘90s Democrats or anything else.

TLDR: I'm starting from an assumption about Rogan's suggestion, namely that he sees the reason CO₂ concentrations have been going up so much and so quickly is largely due to a combination of the tremendous level of deforestation we've done over the last century and we've been pumping out huge amounts of CO₂ since the beginning of the Second Industrial Revolution. As such, the existing forests seem to be busy and already accounted for, or they would be compensating and we would be getting back to some kind of equilibrium. Therefore, according to Rogan, we either need to dramatically slash CO₂ production or plant loads of trees, or both. From there I notice that:

A) there's just too much CO₂ production for how little absorption even the biggest, longest living trees actually do;

B) there isn't enough space (that isn't already forest or agricultural land) even if you were insistent upon treeplanting;

C) the time and cost associated with tree production and planting at scale would make it prohibitive even if none of the above was operative; and

D) it seems you should also just plant lots more trees, for their own sake, anyway

I’m someone who has argued that automobiles are actually the most significant source of the greenhouse gas (carbon dioxide, methane, and nitrous oxide) problem. Folks love disagreeing with this for some reason. Mostly they like to look at the largest scale, at numbers for greenhouse gas producing sectors of the economy, and they like to talk about agriculture or industry or electricity production. But if you zoom down just one layer from the broadest sectors to the subsectors composing each of those, personal light-duty vehicles are by far the largest contributor of GHG out there. They make up 57% of the total transportation output, compared with something we think of as being particularly polluting like aircraft, which contributes only 8% or shipping and boats which is far less than that. I wrote about this in an essay in 2022 I called In the Driver’s Seat.

So, to make this whole discussion very simple, and as generous to the argument as possible, let’s just talk about automobiles and the carbon dioxide they produce. You can pretend they’re irrelevant to the problem and I’ll pretend personal vehicle emissions is something individuals could actually offset and feel good about by planting a few trees, as Rogan suggests.

Great. So how much CO₂ does a typical vehicle push out in a typical year? Organizations like the US Environmental Protection Agency and Natural Resources Canada offer numbers. (In case you’re wondering, these are not “environmental” in any sense but consistently demonstrate they’re just big industry advocates forwarding the economic interests of whoever the current government is and whichever big resource extraction companies are backing them.) Those folks suggest a typical automobile produces 4.6 metric tons of CO₂ annually. This number is funny for all kinds of reasons. Too, it doesn’t translate to Canada, which, as I understand, has a lower proportion of electric vehicles, more SUVs and trucks, and lower fuel economy standards than the US… But let’s just go with this, a generous figure and the path of least resistance. That’s the individual source and volume of the CO₂ were trying to deal with. Now what about the trees doing the capture and sequestering?

I'm told plants like bamboo and foxglove-tree consume a lot of CO₂ but it looks like the oldest live to just a few decades. So those don't seem like great investments. That said, even large, long-lived, perfectly healthy, and fully mature trees living under ideal conditions (think the old growth rainforest of the Pacific northwest) still cannot consume anywhere near just one metric ton of CO₂ in a year. Not even close. And it’s not even 10% of that either. Annual CO₂ consumption for a very large, old, and happy Douglas fir is estimated to be less than 22 kilograms or 0.022 metric tons. (Some recent sources cite things like "the average tree absorbs an average of 10kgs of CO₂ per year for the first 20 years." You can check out the Carbon Offset Guide for a list of other reference.) But, as you'll see, the number can go wildly in any direction and it matters little.) If my math is right, at 22kgs of consumption, more than 210 such trees are needed to deal with the above 4.6 metric tons produced by just one vehicle in just one year. Okay. So what about an entire population?

In a small town like where I live, the whole regional district has in excess of 300,000 registered road vehicles. Multiplied by 210 CO₂ suckers, that’s more than 63 million trees needed. And for a province of just 3.4 million registered vehicles (less than half the number in, say, Los Angeles county) the requirement would be around 714 million trees. Canada has around 26 million vehicles registered (excluding construction, farm, off-road and other CO₂ generating vehicles.) Multiplied by 210, you have yourself a nearly 5.5 billion tree requirement.

As someone who has treeplanted and spend his life in and around the forest, I feel confident saying that even the smallest figure, 63 million, is a lot of trees. So dealing with that CO₂ alone would require not just an impossible number of trees but an almost unimaginable investment of time and resources. However, let's just forget about nearly all the obvious barriers.

To make the investment worthwhile you probably want a North American native species, like the aforementioned Douglas fir or maybe giant sequoia (who have the added benefit of being fire resistant and food and home to many local species) that can get really big and live a long time, consuming carbon and converting it into wood, sequestering it away for centuries. But, obviously, no one can get their hands on or plant many millions of fully mature trees and even if you wanted to do so those would take half a century or more to produce. So, you’re after immature trees.

Trouble is, you can’t even get your hands on many millions of immature trees. Even in this province where millions of trees go to the forestry industry to replant what is logged, that capacity is spoken for. But never mind. Let’s just say capacity can be ramped up and let’s say neither cost nor manpower are factors, either. Pretend Elon Musk freely donates his first 200,000 AI powered automatons to growing automobile-offsetting forests and he: pays for all the trees, construction and operation of all the facilities to grow them, and all the costs associated with shipping and planting, too. Great. Unleash the robot treeplanting army! You still have to contend with some aspects of reality.

In wilder landscapes Douglas fir can grow almost a hundred meters tall (250 feet) while in more urban settings they typically only get to about a third of that. In an ideal setting, they grow centimeters a year, not meters, and take, as above, 20-30 years to develop sufficient foliage to absorb significant amounts of CO₂. It’s about 50-100 years for them to achieve their full potential. Still, pretty quickly they have 5-6m meter (15-20ft) canopies and root systems about as wide, meaning the trees need to be planted about that far apart.

All of this (wild fiction) translates into needing tremendous volumes of free land, ideal land for growing large trees, even to entertain the project at the smallest scale — just to cover the CO₂ for one town. To ensure tree health and everyone is getting the light and nutrients they need (just for a could of decades while they're not consuming much CO₂), sadly, you can’t just pack them into front yards and ditches and highway medians (which would only create further chaos of lost limbs and downed trees during weather events.) But, let's pretend you can. Turns out where you plant is actually kinda irrelevant. To deal with just the CO₂ from one car, just 200-220 Douglas fir, you probably need one to two acres of land.

Again we'll ignore reality. In the wild, the larger the Douglas fir the fewer of them in a particular region. You only find about 20 fir trees per acre once they hit about 30m of height. And even with western red cedar and hemlock fill in underneath, taking up the shaded understory, you only see about 60 trees total in an acre of land. (See: Using Reference Conditions in Ecosystem Restoration: An Example for Riparian Conifer Forests in the Pacific Northwest.) Never mind reality.

This spatial requirement, just 1.5 acres for 210 trees, means the town I live in, with 300,000+ vehicles, would need more than 450,000 acres (1,821 km² or 703 mi²) of land to plant carbon offsetting trees. That sounds like a lot of land. Without really thinking about it I'm pretty sure that just about everywhere that isn't currently a forest is a farm, residential district, industrial park, commercial building, and everywhere else is a road or parking lot or just unsuitable for planting forests. So unless we plan to have the AI also engineer a method for floating forests in the sky above cities or upon the ocean, I'm not sure this thing is going to happen.

But how much land is 1,821 square kilometers? Well, all of Greater Victoria, all the land from the ferry terminal up at Sidney, south through the Saanich Peninsula (and all the farms and forests, beaches and lakes) to downtown, and all of communities to the west, including Langford, Metchosin, and Sooke combine to an area of just 700 km². So if you dug up all the streets and flattened all the homes and offices to plant forests and also converted all the farms to trees you still wouldn't be anywhere close.

If the Artificial Superintelligence figured out how to build tremendous artificial island forests and could park those out on the ocean, it would take an area equivalent to 10 Salt Spring islands. Those would fill the whole area of the Salish Sea, between Vancouver Island and America's Olympic Peninsula, forming a land bridge from Victoria to Port Angeles and cover most of the sea going west, all the way out to Port Renfrew and Neah Bay.

Right.

Are you starting to see the problem?

We should totally plant billions of trees. I'm all for it. Why not? But notice that attempting to address just 10% of the carbon dioxide from cars and trucks alone by treeplanting is perfectly undoable. Now notice we haven’t even talked about offsetting the CO₂ production from residential buildings, commercial aircraft, the iron and steel industries, any agriculture, coal- or gas-fired power plants, or ammonia production (used for water purification, cleaning supplies, refrigeration, and the production of countless plastics, fabrics, and fertilizers), or anything else.

Right.

Now you have a sense of how small the planet is and for how significant even just some human impacts are. And now we can answer the question: Who's being ridiculous?