- cross-posted to:
- science@lemmy.world
- cross-posted to:
- science@lemmy.world
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Successive Canadian gov’ts playing with CO² forest and harvesting data to make it seem like those gov’ts are acting responsibly - an “assumption” that the 2023 fire season blew out of the water - should piss us all off.
Gov’ts are supposed to serve us, not themselves or their corporate overlords.
Maybe it’s time we the people should use the next big fire season for a mass BBQ.
https://www.frontiersin.org/articles/10.3389/ffgc.2023.1297301/full
We found that between 2005 and 2021, forestry in Canada represented a net source of carbon (annual mean = 90.8 Mt. CO2e), and that total area logged was a significant predictor of net forestry emissions. In contrast, Canada’s NIR reported a small net carbon sink during the same time period (annual mean = −4.7 Mt. CO2e).
We show this discrepancy can be explained by Canada’s GHG reporting approach that claims GHG emissions from wildfires are natural, but GHG removals from forests at the age of commercial maturity, despite being primarily natural disturbance origin, are anthropogenic. This reporting approach may lead to climate mitigation policies that are ineffectual or detrimental to reducing net carbon in the global atmosphere.
I’m going to have to read this report. How does that work? There’s no way cutting down a tree, shipping it and processing it requires a tree-worth of fuel. Yeah, you could let the forest keep growing, but from what I’ve heard it slows down pretty good at a certain point, and eventually starts decaying as well. Maybe way more of it is going to paper than I would have expected?
There’s no way cutting down a tree, shipping it and processing it requires a tree-worth of fuel.
Let’s fact check that:
(TLDR: it seems you’re right)
(Note on gross vehicle weights. I found everything from 80,000 kg at the high end in Canada and 80,000 pounds consistently in the US. That wide range, especially the huge difference between Canada and USA, makes me somewhat suspicious of the following calculations. But I think it still works out in favour of the original assertion.)
1 m³ of diesel contains 38.68 GJ of energy.. That means 38.68 MJ/litre.
Air dried logs (20%) moisture have 14.7 GJ per tonne. That’s 14.7 MJ/kg.
Ballpark empty weight of a semi truck and trailer is 35,000 pounds (15,876 kg).
Canadian maximum weight limit for semis is 80,000 kg. I’ve seen numbers varying from about 35,000 kg to 80,000 kg, depending on jurisdiction, trailer configuration, and permits, so I’ll use the biggest number.
That leaves an estimated payload of about 64,000 kg. That amount of wood contains about 940,800 MJ of energy.
Average fuel efficiency is 39.5 L/100 km as of 1999. That’s 1,527.86 MJ.
The payload contains over 600 times the energy required to haul it 100 km. Obviously, there are considerations of actual distance, round trips, logging equipment hauling and use, etc. The numbers can change dramatically based on actual payloads, too, but it seems the lumber has “energy to spare” so to speak.
the metric of concern here isn’t GJ, but tonnes of carbon emitted.
“They did the math”. Thanks!
I’d be a bit more conservative with some of those numbers. I don’t actually know how much they let the logs dry; it could be they’re usually shipped green to avoid damage to them at the site of felling. Furthermore, 1,000km might be a more typical distance for wood to be shipped in Canada, since most of the forest is way up north, far from population centers. We’ve still got comfortably an order of magnitude, though.
Cutting the logs down to size probably takes negligible energy by comparison, and is going to be electricity-based at this point anyway. I’d also have used carbon mass rather than energy, but that’s actually going to work in our favour, because petroleum gets a lot of it’s energy from the hydrogen within it as well, while wood is effectively carbon+water for plant biology reasons.
Oh yeah, it has a lot of holes! Despite the effort I put in, I should have called it what it is: back of the envelope analysis. The only reason I did it was to satisfy my curiosity regarding the initial statement, then felt compelled to share it. :)
I doubt they let the logs dry at all, but the only caloric content I could find for logs assumed air-dried to 20%. I don’t know enough to consider other methodologies like carbon content, etc.
My 100 km was intended as a rate of energy consumption, not an actual hauling distance, but I didn’t make that clear.
This is the best summary I could come up with:
Canada’s forestry sector is responsible for far more greenhouse gas emissions than show up in official tallies, potentially leading to policies that aren’t in line with the country’s climate goals, a new study suggests.
The debate over how much carbon is being absorbed or lost by Canada’s forestry sector comes down to the way the federal government does its emissions accounting, said Anthony Taylor, an associate professor of forest management at the University of New Brunswick and one of the study’s co-authors.
The “inclusion of that sink is what’s causing the biggest difference between what Canada is currently reporting as the emissions from the forestry sector versus what we found in this study,” Taylor said.
The study adds to a growing body of research and reports calling into question the way forestry sector emissions are calculated, and the way the industry is managed.
“These methodologies are built on authoritative information that is accepted by subject matter experts and based on mature science,” said Cecelia Parsons, a ministry spokesperson.
He was co-author of a recent study published in the scientific journal Nature that estimated global wood harvests will add 3.5 to 4.2 billion metric tons of greenhouse gases to the atmosphere annually over the coming decades.
The original article contains 948 words, the summary contains 205 words. Saved 78%. I’m a bot and I’m open source!
