[Bonjoy]

It’s very useful. Now that I realise how much CO2 I have saved by not having another 6 children, I’m pretty much free to have any carbon footprint I want, it’s a carbon free bonanza.

Well yes. In a world where one side excuses their family size on the basis of what type of milk they drink, and the other half excuses their lifestyle on the basis that they're a genetic dead end, then we're all fucked. But at least everyone's got someone else to blame.

[Bonjoy]

each child adds about 9441 metric tons of carbon dioxide to the carbon legacy of an average female, which is 5.7 times her lifetime emissions

I don’t feel I need to explore the methodology here because this so is clearly not a useful answer to any sensible question.

Not useful or not likely to be accurate? It's very useful if accurate... The problem is that it's not likely to be accurate if we assume that we get anywhere near net zero goals!

Not accurate as you say, not useful because it doesn't the define the period that the 9441 tonnes is emitted over (200, 300, 500 years?) and then it arbitrarily applies all those emissions back into the 50 year lifespan of the orginator as a yearly number.   Why not just divide by the total emission period?

Define useful.
Your argument looks like conflation of accuracy and usefulness. You're suggesting zero utility, which suggests usefulness is binary, which it might be, but it depends what 'use' you are making of something.

[abarro81]

If you just think of these as being arbitrary units encapsulating the total impact of a decision then it may make more sense, rather than fixating on the "per year" aspect of the unit chosen

not useful because it doesn't the define the period that the 9441 tonnes is emitted over (200, 300, 500 years?)

I've not checked but presumably they just worked out whatever figure you trend towards over time, it will presumably be asymptotic to some value.

and then it arbitrarily applies all those emissions back into the 50 year lifespan of the orginator as a yearly number.

See my post. We can divide all our numbers by 50 or not. Who cares! It's the same - it's an arbitrary decision that it doesn't affect the result at all. I don't think you've really read my posts - just think of this as arbitrary units covering a total impact from a single decision, you're getting hung up on the conversion to "per year of life left" but it doesn't change anything.

Why not just divide by the total emission period?

As above. Because then you'd need to divide your other impacts by that period to allow for comparison - you're just saying divide by 500 (actually probably infiity) instead of 50. It doesn't change the ratios. Dividing only one thing by that figure is terrible idea since it doesn't answer the question of "what overall impact does choice X have" (and would be rejected by any sensible reviewer!). Again - see my post. Whether we use "CO2e total" or "CO2e per year life remaining" makes no difference to the conclusions.

[petejh]

It’s very useful. Now that I realise how much CO2 I have saved by not having another 6 children, I’m pretty much free to have any carbon footprint I want, it’s a carbon free bonanza.

I didn't realise you a were multi-millionaire who could do whatever you please without limitations on your lifestyle.

You wouldn't *save* a gram of CO2 emissions by not having another 6 kids. You'd just not be contributing *additional* CO2 to what you were contributing with n-6 kids. Personal lifestyle choice innit.

[petejh]

And Barrows it doesn't change anything about the calculation of total impact. But the time period does change everything. Because the problem to be solved is time limited - we have around 20-30 years to really make big reductions in CO2 emissions, or the climate will warm by more than 2 degrees. See 'usefulness versus accuracy'.
Accurate = the maths of 'one fewer child' is the same over whatever time period. Usefulness = we need the biggest reduction in the shortest time (within boundaries - world war would be shit).

Which conveniently brings us back to why the choice to have 'one fewer child' is so useful! Because it's the largest reduction of CO2 in the shortest time, all else being equal (e.g. continuing to eat sausages).

[andy moles]

You could carbon offset your child by murdering someone else.

Maybe you could even make them carbon negative if the person you murder is a frequent-flyer carnivore who drives an SUV and intends to have lots of children 

[petejh]

See 'effective altruism' and why means might not justify ends. Sam Bankman Fraud etc.

[andy moles]

Damn, thought I was onto something 

[IanP]

Why not just divide by the total emission period?

As above. Because then you'd need to divide your other impacts by that period to allow for comparison - you're just saying divide by 500 (actually probably infiity) instead of 50. It doesn't change the ratios. Dividing only one thing by that figure is terrible idea since it doesn't answer the question of "what overall impact does choice X have" (and would be rejected by any sensible reviewer!). Again - see my post. Whether we use "CO2e total" or "CO2e per year life remaining" makes no difference to the conclusions.

I have read your comments , not really sure what you don't understand.

You say 'Dividing only one thing by that figure is terrible idea' which is exactly what is been done - dividing future emissions from the future across a much shorter period and then trying to compare that number to actual emission reduction for an actual single year.  As you say a terrible idea and I agree  .

[abarro81]

I don't know how to explain it more clearly, but I'll give it one more go.

Starting Q: "What is the impact of choices X, Y and Z on total future emissions?"
Method:
1. Work out total future emissions arising as a result of choice X/Y/Z (using an assumption of, say, 50 yrs of life for the person under consideration)
2. Either present those figures ("CO2e total"), or adjust to a more relatable metric/unit e.g. "CO2e per year of life remaining for the person making the choice" by dividing the total values by your assumption for remaining lifespan. Since you get the same ratio either way, it doesn't really matter what you choose. You can even use arbitrary units to make it easier for people to understand. Whichever you choose it allows you to sensibly compare total impact on emissions for those choices. Inconveniently, since it seems to confuse people, when expressed in a per-year-of-life-remaining sense this figure for, say, going vegan is the same as the figure for the metric of "direct impact next year" - but that's not what we're trying to measure here, we're trying to measure total impact. If you want to measure direct impact next year then you take a different approach. You may think that measuring direct impact next year on emissions is more interesting, but it's not if you want to understand the total impact on emissions of a given choice (by definition!).

Obviously future emissions are not the same as immediate emissions given the imperative to act now. Again, to solve this you could use some kind of weighting factor (in addition to the learning rate/deflator that should account for emissions changing over time) - a bit like a discount rate (this might be a good way to address Pete's comment). But you would just be weighting emissions to come to a "total impact" figure that's more accurate

[shurt]

I find Dave's responses to people on social media pretty weird. As has just been said, arguing that McDonald's is totally fine for the environment and that mass global meat production and consumption is having no effect on the planet is crazy.

Eating less meat (ideally going plant based) is a common thread on pretty much everything I've either watched or read about reducing the planets temperature. The % of US agricultural land that's used for beef alone is startling, can't remember the stat exactly but it's over 80% I think (pls shoot me down if wrong).

Personally I think Dave's experiment is well gash.

Not shooting you down as such but that number seemed very off to me and wanted to check for my own knowledge... Googling '% of USA farmland used for cattle' gave me the number 40% still pretty high but slightly different ball park.

I know this has now moved on to Co2 and kids but wanted to clarify my dreadful stat errors. I was quoting something very badly I'd read which I found crazy. Over 30% of all crops grown in the US are to feed cattle. Less than 20% for veg for humans. Yes it was US based but a la Andy Popp I've been off meat for years due to farming conditions and now environmental reasons. I never ate meat again after watching the doc Land of Hope and Glory about the UK meat industry.

Yes we need to reduce Co2 but Methane is a massive issue too and meat production is a huge contributor to the gas which is up to 80 times worse (especially in the short term) than Co2. It's complicated but as many have said we've only got 20-30 years until it's all lost, there's not enough being done. The future feels grim, especially for my two kids.

That's right nail me up on a Co2 crafted cross. In my defense I haven't been on a plane for a fair few years and find it hard to justify...

[User deactivated.]

The UK's birth rate is circa 1.5 per woman. This is problematic because it is too low. Damned if.you do, damned if you don't.

[petejh]

Yes we need to reduce Co2 but Methane is a massive issue too and meat production is a huge contributor to the gas which is up to 80 times worse (especially in the short term) than Co2.

Methane (and other gasses) has been taken into account in the calcs used for the main 4 lifestyle impacts of not eating meat, having one fewer children, not driving, taking one fewer trans-atlantic flight.  It's why the metric used is tons of CO2e (for CO2 equivalent), not CO2.

[teestub]

The UK's birth rate is circa 1.5 per woman. This is problematic because it is too low. Damned if.you do, damned if you don't.

Too low in what terms? It’s normally people like Musk and Bezos who complain about this as they need a bigger population to but their shit to support our current economic model!

[IanP]

I don't know how to explain it more clearly, but I'll give it one more go.

You really don't need to.  I understand what you're trying to say, just don't agree with your conclusions.  Similarly I could try to explain my position  again but I'm on my phone and I'm sure it wouldn't change your views either 😃.

[Will Hunt]

Life is a pyramid scheme, Stubbs. Gotta keep pumping out the kids so there's somebody to pay our triple-locked pensions when we're old...

[abarro81]

I don't know how to explain it more clearly, but I'll give it one more go.

You really don't need to.  I understand what you're trying to say, just don't agree with your conclusions.  Similarly I could try to explain my position  again but I'm on my phone and I'm sure it wouldn't change your views either 😃.

My conclusions about what? I really can't see what in my last post you could possibly disagree with? Quote it back to me with an explanation...
I really hope you don't work in analysis in any way!

[IanP]

I don't know how to explain it more clearly, but I'll give it one more go.

Starting Q: "What is the impact of choices X, Y and Z on total future emissions?"
Method:
1. Work out total future emissions arising as a result of choice X/Y/Z (using an assumption of, say, 50 yrs of life for the person under consideration)
2. Either present those figures ("CO2e total"), or adjust to a more relatable metric/unit e.g. "CO2e per year of life remaining for the person making the choice" by dividing the total values by your assumption for remaining lifespan. Since you get the same ratio either way, it doesn't really matter what you choose. You can even use arbitrary units to make it easier for people to understand. Whichever you choose it allows you to sensibly compare total impact on emissions for those choices.

I'm not sure anyone really wants to carry this on or that you really want to understand my argument but here goes.

I don't agree that dividing the CO2e total by the lifespan simply doesn't matter - why does that make the figure more relatable as opposed to more confusing?  CO2 emissions that happen in the future happen in the future - if you want to place the CO2e total in context then give the total and period over which the total is calculated.  Assuming the calculation is for an infinite converging series you could for example give the time period over which 90% of the emissions occur or give actual CO2e number for the lifespan of the individual (i.e. actual emissions) and divide by the 50 to give the impact over the persons lifespan, then give the post lifespan CO2e total.  If you want more context  then what are the average CO2 emissions per year for years 50-100, 100-200 etc?

To me stating  "CO2e per year of life remaining for the person making the choice" is not simply an abstract choice it is a contextually disingenuous way of presenting the data.

The original statement:

'We recommend four widely applicable high-impact (i.e. low emissions) actions with the potential to contribute to systemic change and substantially reduce annual personal emissions: having one fewer child (an average for developed countries of 58.6 tonnes CO2-equivalent (tCO2e) emission reductions per year), living car-free (2.4 tCO2e saved per year), avoiding airplane travel (1.6 tCO2e saved per roundtrip transatlantic flight) and eating a plant-based diet (0.8 tCO2e saved per year)'

Questions:

If I avoid car travel will I save on average 2.4 tCO2e next year - yes
If I avoid car travel for the next 50 years will I save on average 120 tCO2e - possibly depending on what happens to CO2 emissions from car travel over the next 50 years but it is relatively sensible estimate of the potential scale of the number.

If I don't have a child now will I save on average 58.6 tCO2e next year - no, nowhere near the actual number will be much smaller.
If I don't have a child now will I save over the next 50 years on average 2930 tCO2e - no, nowhere near  the actual number will be much smaller.

[Moo]

After carefully reading all of the posts and examining the data on this thread I have concluded that Dave Mac is a silly sausage.

[Wellsy]

After carefully reading all of the posts and examining the data on this thread I have concluded that Dave Mac is a silly sausage.

A silly vegan sausage or meat sausage?

[shurt]

After carefully reading all of the posts and examining the data on this thread I have concluded that Dave Mac is a silly sausage.

Agreed.

The man speaketh once more...

https://www.instagram.com/p/ClI7KMLIvHI/?igshid=YmMyMTA2M2Y=

[andy popp]

Why does he insist on calling this an experiment when it's clearly no such thing.

[andy moles]

I'd be a bit concerned for his wellbeing right now. A dark and rainy month of eating nothing but McDonald's burgers while seemingly spiralling into a social media vortex of his own creation. 

(edit: typo)

[abarro81]

Why does he insist on calling this an experiment when it's clearly no such thing.

Why is it not? If I tried doing 6 hrs aerocap a week I'd call it an experiment with my training... Obviously an n=1 one, but there's only one n I care about! "Experiment" seems fine, possibly as shorthand for "experiment on myself"; something like "study" would seem more weird

[andy popp]

Study would be just as weird. But it doesn't meet the threshold for experiment in anything but the most colloquial sense. It's one thing to tell your mates you're experimenting by doing X hours of aerocap, but another for a well-known climber (and well-known in part for his highly scientific approach to sports performance) with a large following to publicly promote this as an "experiment" on social media.

That said, I really don't care (that much) what he calls it.