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Comment by zests | Hacker News Reader

Think about it. Cows release carbon based green house gasses. Where does that carbon originally come from? Plants absorbing carbon based green house gasses. I'm not saying that they cancel out, but there must be some consumption of carbon from the atmosphere in order for cows to produce carbon.

If you're an environmentalist trying to convince people to support your cause, you aren't going to talk about the carbon that raising cows removes from the air. You're only going to mention the carbon that gets put back in the atmosphere. That way, the problem seems like a bigger deal. This is not a slight on environmentalists -- its just politics.

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If we were just talking about the CO2 exhaled by cows I would agree. Plants consume CO2 to grow, cows release a lot of that CO2 back into the atmosphere. It's a closed loop (if we ignore all the energy we spent on farming).

The problem is that cows also release a lot of methane. Methane is carbon based (CH4), but it acts very different from CO2. It decays faster, but it a much more potent greenhouse gas than CO2. It's around 80 times more potent in the first 20 years, or 25 times more potent in the first 100 years. So having plants absorb CO2 only for cows to turn it into methane is pretty bad on the timescales we care about.

It's not necessarily the biggest of the problems with cattle, but it's worth preventing on its own.

Note conversion of C02 into methane.

If methane has bigger effect than the same amount of coal within C02 then your argument fails.

> While CO2 persists in the atmosphere for centuries, or even millennia, methane warms the planet on steroids for a decade or two before decaying to CO2.

> In those short decades, methane warms the planet by 86 times as much as CO2, according to the Intergovernmental Panel on Climate Change.

https://www.scientificamerican.com/article/how-bad-of-a-gree...

A somewhat surprising corollary: if you have methane and you can burn it, it's better to do that than vent it directly.

(Of course, better still to leave it in the ground, if that's where your methane is coming from...)

Natural gas burns cleanly and is very effective at heating homes and water. While there are problems with leakage, it's a huge step up from burning coal & oil.

@nightski Yes, natural gas is about half as bad as burning oil and one third as bad as coal in terms of energy output per tonne of CO2 emitted.

Although methane is usually the largest component, natural gas is typically a mixture of methane, propane and butane. So not quite the came as cow burps.

Not quite. For a power plant the rate is ~0.059 tons CO2 per MMBtu of natural gas, coal is ~0.105 tons per MMBtu (different for bit, sub, etc.), and oil is around ~0.081 (although, like coal, it varies).

Now, in a power plant context, modern gas plants are going to be more efficient and have better heat rates than their coal and oil equivalents, so you do generally need less total MMBtu input to get an equivalent amount of generation out. But if you’re burning the same amount in terms of energy content, the difference when it comes to only CO2 is not as large as you’re saying.

Do you find it strange that an article about methane does not mention what percentage of the greenhouse gas effect that methane accounts for? I'd ask everyone to read this article, write down what percentage you think methane accounts for and then read the wikipedia page on greenhouse gasses.

This is to say nothing other than that more nuance is needed when discussing the environment. It is important to reduce our emissions.

https://en.wikipedia.org/wiki/Greenhouse_effect#Greenhouse_g... https://en.wikipedia.org/wiki/Methane_emissions#List_of_emis...

This is what I don't understand about companies planting trees to offset their fossil fuel CO2. Our problems are heavily caused by carbon being dug out of the ground and released. A tree just means that the carbon will be released at a later date

It's mostly feel-good greenwashing, as far as I can tell.

Bill Gates recommends a company for doing offsetting that actually pulls carbon out of the air and sequesters it underground, removing it from the carbon cycle: https://climeworks.com/subscriptions

It appears to cost ~$1/kg, but I'm guessing that will come down substantially if they're able to scale it up.

Well, a tree removes quite a lot carbon for quite a long time. Just let it grow for a century or so.

Good point. Not sure if they're allowed to grow for that long, I think some options are on timberland. But if they are, it seems like a reasonable short-term help.

In order to be usable, you 10+ years anyway. And in case you don't burn the wood, the CO2 stays out of the CO2 cycle for even more years anyway.

And by planting the right kind of trees, we could even go a long way to repair and safe our forests which are suffering from climate change and monocultures.

We also need to be restoring all the tree cover that we’ve been removing. Trees do more than just storing carbon. They provide us with oxygen, hold top soil together, provide natural habitat for various wild life, cool an area enough to attract rain clouds, and much more.

Though, replacing the cover isn’t enough and more needs to be done - such as reducing greenhouse gas emission and removal of greenhouse gasses ( by using Carbon Capture Systems, for example).

I think the assumption is that:

1. the tree will eventually be replaced by another tree, but more trees are being planted overall than are dying, so their numbers go up

2. the time dimension matters a lot. i.e. sequestering lots of CO2 inside trees now is still useful even if it gets released later because by then maybe technology will have improved to be less fossil fuel dependent.

And the carbon in methane degrades back into water and CO2. It's part of the water cycle.

Fossil fuels are the problem.

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