Climate Change - The Scientific Debate (Vol. II)

[ludo]

robinessex said:

durbster said:

wc98 said:

durbster said:

This sounds very much like, "I don't understand it therefore nobody does".

The climate has behaved pretty much exactly as we expected it to. Clear proof that we do understand it.

that is b/s.

Do you dispute the fact that the temperature has risen as expected from the increase in CO2?

Yes. bks. Prove that beyond doubt, please. ...

Nothing can be proven beyond unreasonable doubt.

[durbster]

robinessex said:

durbster said:

wc98 said:

durbster said:

Do you dispute the fact that the temperature has risen as expected from the increase in CO2?

that's it ? nothing on yet another settled science area not being settled at all ?

Using the fact that science is constantly refined over time as evidence against the underlying theory is illogical. There are no scientific theories that can be considered proven, according to that logic, so it's pointless responding to it.

So yep, that's it. And the answer?

Can you re-type that in English so we can all understand it

We are still discovering new things about evolution.
That does not mean that the theory of evolution is wrong.

[wc98]

durbster said:

We are still discovering new things about evolution.
That does not mean that the theory of evolution is wrong.

do you agree we don't understand the theory of evolution completely and might make new discoveries that render the current theory incorrect ?

[ludo]

wc98 said:

do you agree we don't understand the theory of evolution completely and might make new discoveries that render the current theory incorrect ?

can you suggest a branch of scientific research where that is not the case.

All science is provisional and subject to revision.

ETA: can you suggest what a new discovery that would render the theory of evolution substantially incorrect would look like?

[Kawasicki]

ludo said:

Kawasicki said:

Yeah, loads more.

Any consensus estimate on something as simple and incredibly important as predicting the start of the next ice age? Your assertion was that we understand our climate, the answer should be easy then.

Stay focused!

Except it isn't simple, is it? It depends on many things, one of which is the composition of the atmosphere, and we are constantly altering that. We can't predict fossil fuel emissions as they depend on political and economic considerations.

ETA: it also isn't that important either AFAICS. DO any of the estimates suggest an ice age is imminant (withing, say the next 1,000 years)?

Edited by ludo on Thursday 28th March 16:48

Durbster is confident that we understand how our climate functions...

Kawasicki said:

durbster said:

wc98 said:

durbster said:

This sounds very much like, "I don't understand it therefore nobody does".

The climate has behaved pretty much exactly as we expected it to. Clear proof that we do understand it.

that is b/s.

[Kawasicki]

LoonyTunes said:

What???

Why are you talking in riddles? Just post your actual point, including the science behind it, so that it can be debated FFS.

Global cooling when it occurs is due to aerosols and dangerous feedbacks.
Global warming when it occurs is due to CO2 forcing and dangerous feedbacks.

The scientific theories behind both of these scenarios is well understood. I can point you to hundreds of peer reviewed papers to support these basic theories, if you deny the science.

[grumbledoak]

This floated across my twitter feed,

from https://twitter.com/TADinKaty/status/1111836398024...

I haven't checked the numbers, but the links are there if you want to.
It looks like every "put it in perspective" chart I've ever seen.
Where is the obvious cause for alarm?

[ludo]

Kawasicki said:

ludo said:

Kawasicki said:

Yeah, loads more.

Any consensus estimate on something as simple and incredibly important as predicting the start of the next ice age? Your assertion was that we understand our climate, the answer should be easy then.

Stay focused!

Except it isn't simple, is it? It depends on many things, one of which is the composition of the atmosphere, and we are constantly altering that. We can't predict fossil fuel emissions as they depend on political and economic considerations.

ETA: it also isn't that important either AFAICS. DO any of the estimates suggest an ice age is imminant (withing, say the next 1,000 years)?

Edited by ludo on Thursday 28th March 16:48

Durbster is confident that we understand how our climate functions...

Understanding is not binary. Pretending it is is a shabby rhetorical ploy.

I note you do not address the substantive points that I made. Plus ca change...

[ludo]

grumbledoak said:

This floated across my twitter feed,

from https://twitter.com/TADinKaty/status/1111836398024...

I haven't checked the numbers, but the links are there if you want to.
It looks like every "put it in perspective" chart I've ever seen.
Where is the obvious cause for alarm?

LOL, playing with axes to mislead the reviewer is a very old trick and ought not to fool anybody. DenialDepot has parodied this behaviour on several occasions, but blogs seem to never tire of it.

In this case, using the seasonal cycle to define the axes is obviously disingenuous. It is basically implying that we don't need to worry about climate change until it is of similar proportions to the seasonal cycle (i.e. > 20C for the U.K.). It ought to be obvious to anyone that climate change that made our summers like our winters would have a very significant effect on agriculture and the economy.

ETA: also one wonders why they chose US temperatures rather than global ones...

[grumbledoak]

ludo said:

LOL, playing with axes to mislead the reviewer is a very old trick and ought not to fool anybody. DenialDepot has parodied this behaviour on several occasions, but blogs seem to never tire of it.

Are you suggesting that a plot of only the moving average and the CO2 would show similar slopes? That looks unlikely.

[ludo]

grumbledoak said:

Are you suggesting that a plot of only the moving average and the CO2 would show similar slopes? That looks unlikely.

For a start, equilibrium temperature is related logarithmically to CO2 concentrations. I'd use annual anomalies if I were going to do a comparison (usual way to eliminate the annual cycle). There is also the fact that CO2 isn't the only thing that affects the climate (and nobody claims otherwise), so other forcings need to be considered as well.

However, the slopes are arbitrary, depending on the units of measurement (or equivalently the scaling of the two axes). The only thing you can really tell from a diagram is the corellation (and we all know what that isn't ;o). A better approach is physics.

I don't know about post-industrial climate, but for paleoclimate there is an approximately linear relationship between temperature and CO2, but that is not straight-forward to interpret as CO2 causes changes in temperature and temperature causes changes in CO2 (it can be both a forcing and a feedback).

ETA: a bit of googling shows you can indeed get a good corellation between CO2 and GMST anomalies



but I'd prefer an approach that had a bit more physics, starting with considering the other forcings.

Edited by ludo on Saturday 30th March 08:52

[PRTVR]

ludo said:

LOL, playing with axes to mislead the reviewer is a very old trick and ought not to fool anybody. DenialDepot has parodied this behaviour on several occasions, but blogs seem to never tire of it.

In this case, using the seasonal cycle to define the axes is obviously disingenuous. It is basically implying that we don't need to worry about climate change until it is of similar proportions to the seasonal cycle (i.e. > 20C for the U.K.). It ought to be obvious to anyone that climate change that made our summers like our winters would have a very significant effect on agriculture and the economy.

ETA: also one wonders why they chose US temperatures rather than global ones...

The global temperature is a man made figure, it exists only in a computer program, it serves no function in the real world, the temperatures from America should reflect the global figure should they not as it is a large land mass?

[ludo]

PRTVR said:

ludo said:

LOL, playing with axes to mislead the reviewer is a very old trick and ought not to fool anybody. DenialDepot has parodied this behaviour on several occasions, but blogs seem to never tire of it.

In this case, using the seasonal cycle to define the axes is obviously disingenuous. It is basically implying that we don't need to worry about climate change until it is of similar proportions to the seasonal cycle (i.e. > 20C for the U.K.). It ought to be obvious to anyone that climate change that made our summers like our winters would have a very significant effect on agriculture and the economy.

ETA: also one wonders why they chose US temperatures rather than global ones...

The global temperature is a man made figure, it exists only in a computer program, it serves no function in the real world, the temperatures from America should reflect the global figure should they not as it is a large land mass?

Right, the surface area of the Earth is 510.1 million km², that of the US is 9.834 million km², so that is less than 2% of the globe. It is also 2% that is strongly affected by ENSO on one side and the gulfstream on the other. So no, one would not expect America to reflect the global figure very strongly.

There is also the fact that the average temperature of the US is calculated in exactly the same way as the global mean temperature, so if one is a man made figure that exists only in a computer program, so is the other! The temperature given in weather forecasts is also calculated using a computer, and initialised from station data in the same way, and yet they are useful enough for the commercial world to pay for them.

[grumbledoak]

ludo said:

For a start, equilibrium temperature is related logarithmically to CO2 concentrations. I'd use annual anomalies if I were going to do a comparison (usual way to eliminate the annual cycle). There is also the fact that CO2 isn't the only thing that affects the climate (and nobody claims otherwise), so other forcings need to be considered as well.

However, the slopes are arbitrary, depending on the units of measurement (or equivalently the scaling of the two axes). The only thing you can really tell from a diagram is the corellation (and we all know what that isn't ;o). A better approach is physics.

I don't know about post-industrial climate, but for paleoclimate there is an approximately linear relationship between temperature and CO2, but that is not straight-forward to interpret as CO2 causes changes in temperature and temperature causes changes in CO2 (it can be both a forcing and a feedback).

So a plot of annual average temp vs log CO2 would be interesting. Yes, the slopes are unimportant, as are the actual values. The correlation interests me. As such I'm not sure of the relevance of paleoclimate or even the other forcings. I'm more interested in the "CO2 causing global thermal armageddon and it's all your fault" claims.

Some sort of clear correlation in the raw data would be nice to see, but if such a thing was ever published I missed it.

[ludo]

grumbledoak said:

So a plot of annual average temp vs log CO2 would be interesting. Yes, the slopes are unimportant, as are the actual values. The correlation interests me. As such I'm not sure of the relevance of paleoclimate or even the other forcings. I'm more interested in the "CO2 causing global thermal armageddon and it's all your fault" claims.

Some sort of clear correlation in the raw data would be nice to see, but if such a thing was ever published I missed it.

I edited my early post to add this:

ludo said:

ETA: a bit of googling shows you can indeed get a good corellation between CO2 and GMST anomalies



but I'd prefer an approach that had a bit more physics, starting with considering the other forcings.

"CO2 causing global thermal armageddon and it's all your fault" - could we leave the hyperbolic straw men for the political debate please? It really just gets in the way of discussing the science in an objective manner.

[grumbledoak]

ludo said:

ETA: a bit of googling shows you can indeed get a good corellation between CO2 and GMST anomalies

Looks ok for Mauna Loa since 1950, less convincing the Antarctica data. I note that's a linear plot though. And it's only two locations, quite far apart for splicing datasets.

I'm sure the modelling approaches are fascinating to study, but between the complexity, the proprietary code, the known omissions, and the use of fitting, they struggle to convince.

[ludo]

grumbledoak said:

ludo said:

ETA: a bit of googling shows you can indeed get a good corellation between CO2 and GMST anomalies

Looks ok for Mauna Loa since 1950, less convincing the Antarctica data. I note that's a linear plot though. And it's only two locations, quite far apart for splicing datasets.

I'm sure the modelling approaches are fascinating to study, but between the complexity, the proprietary code, the known omissions, and the use of fitting, they struggle to convince.

(i) as I said, CO2 is not the only forcing, so you would only expect there to be a strong correllation over a period where CO2 forcing was dominant.

(ii) Yes, I pointed that out earlier and gave you a link to a better approach that takes the logarithmic nature of CO2 radiative forcing into account

ludo said:

but I'd prefer an approach that had a bit more physics, starting with considering the other forcings.

(iii) CO2 is well mixed in the atmosphere, so as long as you are measuring the bulk atmosphere (i.e. not influenced by local source and sinks), such as Mauna Loa, then you get more or less the same result (to within 10ppm or so) wherever you measure it.,

(iv) I can tell you didn't bother to follow the link, because it is a simple model, not a complex one, and the code is not proprietary (as pointed out in the article) and anyone can reproduce the results if they have the skills.

ETA: (iv 1/2) and if you mean General Circulation Models, then (a) of course they are complex, the global circulation is complex, what do you expect? and (b) plenty of GCMs are open source and you can download them an compile them if you want, but oddly enough no climate skeptic seems to have bothered.

(v) all models have omissions, models are simplifications of the real world, and thus omissions are inevitable.

(vi) the model isn't "fitted", it is a Bayesian model, and considers the posterior distribution over parameters

(vii) "they struggle to convince." as I said before, nothing can be proven beyond unreasonable doubt, and nobody can be convinced if they are unwilling to listen (or in this case, click on a link and read the article)

Apart from that, your comment was fine.

Edited by ludo on Saturday 30th March 10:56

[ludo]

grumbledoak said:

... but between the complexity, the proprietary code, the known omissions...

I have to say, this is quite funny, objecting to the models being both too complex and too simple in the same sentence! LOL.

[anonymous-user]

ludo said:

grumbledoak said:

... but between the complexity, the proprietary code, the known omissions...

I have to say, this is quite funny, objecting to the models being both too complex and too simple in the same sentence! LOL.

Isn’t this the point? The deniers can always find a reason (if they look hard enough) or don’t understand, to reject the models.

They’re wrong
They’re just guesses
They’ve been tampered with so you can’t trust them
They don’t take clouds into account

Of course none of this is correct but it’s all about confirmation bias and getting the science from advocacy blogs.

ETA clouds.

Edited by anonymous-user on Saturday 30th March 11:37

[grumbledoak]

ludo said:

I have to say, this is quite funny, objecting to the models being both too complex and too simple in the same sentence! LOL.

Fine, I'll clarify. It is tedious to write everything out longhand though. The omissions of known major factors like clouds while ramping minor, possibly immeasurably small, effects such as CO2 reduces the credibility of the models, while the complexity is an issue for anyone who is supposed to be doing other things. Quite different objections, but complementary rather than opposing.