Johnny Ball's environmental science claims

[asthmatic camel]

There is a limit:

We can only burn it as fast as we can find it, and practically speaking since carbon fuels are a valuable commodity we can only burn it as fast as we can find a use for it (e.g. when we need to drive to the shops or turn the heating on).

But the point is, unlike our wood-burning ancestors - the carbon in our fuel was captured a long time ago, so unless we use it all up (unlikely in the near future), there's no theoretical limit on how much we can burn.

In the bad old days if you chopped down the entire forest then by definition you couldn't burn any more. Our ability to emit carbon was once limited by the land's ability to capture carbon. This is no longer the case.

Not really what I was saying. Oxygen is required to burn fuels, and there's only so much of it around. Use more than can be replenished and eventually nothing's going to burn. That's an upper limit, surely?

[Croydon Bob]

spiders

It'll be that Bagheera kiplingi that is to blame! The only methane-producing spider. Stamp them out and the planet will be safe. All we have to do is destroy the Central American rain forests and we're in the clear.

[salimfadhley]

Not really what I was saying. Oxygen is required to burn fuels, and there's only so much of it around. Use more than can be replenished and eventually nothing's going to burn. That's an upper limit, surely?

I suspect that if we were to vaporize our entire stock of carbon-based fuels in a single day it would hardly put a dent in the amount of Oxygen remaining in the atmosphere simply because the atmosphere is so huge compared to all of the man-made fuel stores which currently exist.

A dimly related thought: Pretty much all of the UK's coal reserves were laid down during the carboniferous period, which lasted approximately 1.7 million years. It was used up since the Industrial revolution began, approximately 0.0004 million years ago. Even allowing for a 50% margin of error this suggests we managed to burn most of the coal in England 2000 times quicker than it was ever captured.

( and that's probably an absurdly lowball estimate )

I think it also gives an indication of just how slow natural carbon capture is.

This also reminds me of a Christian fundamentalist I once met who claimed that there was no evidence for the fossil origins of mineral oil, and that to suggest that it's made from the decomposing remains of long-dead critters is all a big lie, hence so is peak-oil.

[Harryprice]

A dimly related thought: Pretty much all of the UK's coal reserves were laid down during the carboniferous period, which lasted approximately 1.7 million years.

Surely the Carboniferous lasted much longer than that, more like 60 million years.

It was used up since the Industrial revolution began, approximately 0.0004 million years ago. Even allowing for a 50% margin of error this suggests we managed to burn most of the coal in England 2000 times quicker than it was ever captured.

It wasn't all used by any means, it simply became uneconomic to mine. There's enough coal in the ground in the UK to power the country for decades. It's just too expensive to bother.
Having said that, at current global coal extraction rates we could reach a coal peak in a few decades, not long after the oil peak.

[salimfadhley]

Stupid me! I confused millions with billions, hence my calculations are at least a factor of 1000000 out.

And yes, we just hit "peak coal" sometime in the early 60s, possibly a long time before that. That doesn't mean that it's all gone, but that the easily extracted coal is gone.

Incidentally, from what I gather the most productive coal mines are "open-cast", where all you need to do is drive into a pit and dig the stuff up. I remember that British coal-pits were mostly deep-seam mines which were phenomenally expensive and dangerous things to operate. It's possible that these were never profitable without subsidy.

Sal

[asthmatic camel]

salim, the niggling doubts I have about the AGW circus centre on the widely accepted fact that atmospheric CO2 levels have been significantly higher in the past without triggering a runaway greenhouse effect. Let's say we extract as much fossil fuel as possible, given an estimate of 200 years' worth of reserves, (I pulled that figure out of my backside, so don't rely on it), how much difference would that really make to CO2 levels, and how much difference would it make in the long term?

My guess is not a great deal. I'd say it's far more likely that humanity will blow itself to bits in a fight for what's left before it kills the planet.

[Tony Williams]

salim, the niggling doubts I have about the AGW circus centre on the widely accepted fact that atmospheric CO2 levels have been significantly higher in the past without triggering a runaway greenhouse effect.

I highlighted a phrase which sounds an alarm bell with me, rather like "as everyone knows".

CO2 is one element in the greenhouse effect; there are several others (eg water vapour, methane, ozone, plus cloud cover) and the degree of the effect depends on the totality of all of them, not one individual element.

CO2 matters now because it is going up steadily, pushing up the totality with measurable results on global average temperatures. And we are responsible for that rise.

[asthmatic camel]

I'm certainly no expert, but isn't it the case that there is plenty of evidence which shows significantly higher CO2 levels in the past? Carbon isotopes in sediment, for example?

[Tony Williams]

I'm certainly no expert, but isn't it the case that there is plenty of evidence which shows significantly higher CO2 levels in the past? Carbon isotopes in sediment, for example?

Please see my previous answer.

Climate scientists have better access to the data than anyone else, and they are almost unanimous in their belief that human activities are causing the current warming trend, with rising CO2 production the main problem.

It doesn't actually matter what happened in the past - we know that at different times the poles have been tropical and at other times the entire planet has been frozen over. What matters is what's happening now, why it's happening, what the effects will be on humanity and what can be done about it. While there is much that is not yet known (particularly the effects on a regional basis) the basic science is regarded as solid.

[Croydon Bob]

I'm certainly no expert, but isn't it the case that there is plenty of evidence which shows significantly higher CO2 levels in the past? Carbon isotopes in sediment, for example?

My understanding is that you are correct. But what I don't understand is whether there were any mitigating circumstances (eg: higher volcanic activity would have been reflecting more heat away from the planet); and what effect this had on climate and temperature (eg: if it was "naturally" hotter and stormier then that still isn't good news for us).

The consensus position is that CO2 levels are now higher than they've been for over 400,000 years. A return to the atmosphere that suited dinosaurs and ferns isn't likely to be good news for mammals and flowering plants.

[FarSideOfTheMoon]

Incidentally, from what I gather the most productive coal mines are "open-cast", where all you need to do is drive into a pit and dig the stuff up. I remember that British coal-pits were mostly deep-seam mines which were phenomenally expensive and dangerous things to operate. It's possible that these were never profitable without subsidy.

Sal

They have some monster open cast pits in China. Seriously frightening stuff.

[Harryprice]

...we know that at different times the poles have been tropical ...

Do you have a link for that - I'd love to read it!

... and at other times the entire planet has been frozen over....

I think 'know' is a bit strong for the snowball Earth hypothesis.

Interesting article about ancient CO2 levels and temperatures here.

[asthmatic camel]

Harryprice, that's not the only contentious claim made. "we know that at different times the poles have been tropical and at other times the entire planet has been frozen over." We don't know anything of the sort. The Snowball Earth Hypothesis remains highly controversial.

ETA. Harry beat me to it.

[Admin]

Johnny Ball famously got slow-clapped off stage after an impromptu climate-change rant. One of the claims he made is something I've heard some (highly educated) colleagues independently repeating - specifically that the anthropogenic global-warming hypothesis must be false because:

"The amount of CO2 produced by man is tiny compared to the volume which is both produced and consumed by life on earth."

Well, I agree that life is probably carbon neutral overall as CO2 expired had to have been consumed in the first place; and the ultimate source of consumption is plant life which was built by extracting CO2 from the atmosphere etc.

But there's an argumentative fallacy being used here: the 'two wrongs make a right' fallacy. If life itself were indeed producing more (deleterious to the environment) CO2 than human activity, that fact still doesn't justify us doing nothing about our own contribution to rising CO2 levels in the atmosphere.

It's a bit like being caught shoplifting and claiming "but others do it as well". That doesn't matter: it doesn't justify what you (or we in the CO2 case) are doing wrong.

I think climate change is becoming a bit of a 'leveller' when it comes to skepticism and critical thinking. It's revealing some highly respected 'voices of reason' as not being quite as rational as we'd thought. Clive James, a few weeks ago, made some atrocious arguments for so-called 'climate change skepticism', and last week even James Randi did exactly the same thing. It really is not good enough for such people to be making arguments like, "I know nothing of the science of climate change, but..."

[salimfadhley]

But there's an argumentative fallacy being used here: the 'two wrongs make a right' fallacy. If life itself were indeed producing more (deleterious to the environment) CO2 than human activity, that fact still doesn't justify us doing nothing about our own contribution to rising CO2 levels in the atmosphere.

Especially when one of the "wrongs" really isn't a wrong!

The reason this fallacy is so effective is that it tricks listeners into comparing a very large (but carbon-neutral) system with a much smaller carbon positive system.

Another variant of this is:

"You say we need to cut down on flying, but aircraft produce less than 1% of artificial carbon-dioxide"

Practically speaking, almost any single industry you care to mention emits less than 1%, but since there are so many different kinds of industry they all add up.