[thrw_skpt]

I see several things about the climate science that can be substantially improved.

* general discourse. Whenever someone raises some objection, the response is not a thoughtful argument, but many times a quick dismissal. you are certainly not one to do that, it is much appreciated

* unfalsifiability. scientific theories should be falsifiable. anything else is religion or politics. For example, what happens if there is a large volcano, or something like Saddam burning thousands of oil wells in Kuwait. I read somewhere that some climate models did check their predictions against the actual outcomes, and this is good. More evidence of this type would be great.

* model and data validation, audit and oversight. I am a quant working with both data and models in finance. I know about model uncertainty, and how messy is real world data. The regulators demand a lot of model testing, documentation, validation, ongoing monitoring, and audit. Our bible is the supervisory letter SR 11-7. Banks are investing billions in this and regulators hired hundreds of people to beef up their oversight. I don't see a similar scrutiny over the climate models that arguably are more important for the humanity

* all results in climate science can be spun to align to the climate change thesis. If there is a large uncertainty about the results, one picks the worse outcome and the result is presented as "new research show that the [melting of Antarctica, let's say] may be happening much faster than previously thought". Well, the same research show that the X thing may be also happening much slower, but who cares about that? If something completely new comes up (e.g. number of trees in the Amazon basin being off by a factor of 10), then more funding is needed.

* the 97% or so consensus of the climate scientists. My perception is that most of them know their own piece, and they are scrupulous, but can't conclude from their area of research one way or another about the whole global warming. They don't contradict it either, so if asked they say that global warming is most likely real. But that's not really a strong consensus, it's a polite agreement to not disagree. Here's a recent example on Hacker News: and antarctic ice researcher did an AMA on HN when his research regarding some Larsen C breakage made waves in the media [1]. The media spin was obviously that the world is getting warmer, and this is new evidence to support that. When someone on HN asked what we can do to stop further ice breaks, his answer was this: "Nothing! This is a completely natural process - ice builds up over time in the shelf and it has to be lost somehow. The calving of the iceberg is, in itself, not a result of human activity. If you mean more broadly how can we help prevent the loss of ice from Antarctica, then I'm not a climate policy expert". This gentleman is clearly a climate scientist, but he does not consider himself a "climate policy expert"

* Freeman Dyson [2] judges the climate models as having too much uncertainty: "The models solve the equations of fluid dynamics, and they do a very good job of describing the fluid motions of the atmosphere and the oceans. They do a very poor job of describing the clouds, the dust, the chemistry and the biology of fields and farms and forests. They do not begin to describe the real world we live in ..."

By the way, I'm not a shill of the oil/coal/car industry. I do have a STEM PhD from MIT, and I can continue with more scientific arguments, but this message is getting already too long. I'm using a throwaway account.

[1] https://news.ycombinator.com/item?id=13365211 [2] https://en.wikipedia.org/wiki/Freeman_Dyson#Climate_change

[Cretin2]

I think you need to understand magnitudes: "For example, what happens if there is a large volcano, or something like Saddam burning thousands of oil wells in Kuwait. I read somewhere that some climate models did check their predictions against the actual outcomes, and this is good. More evidence of this type would be great."

These are trivial in the global context.

Here's a good resource on the global carbon cycle: https://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_Cha...

and to my point from your other comment, this is from the link above: . Within a thousand years, the remaining atmospheric fraction of the CO2 emissions (see Section 6.3.2.4) is between 15 and 40%, depending on the amount of carbon released (Archer et al., 2009b).

The models are performing very well:

https://www.theguardian.com/environment/climate-consensus-97...

Looking to Freeman Dyson as a climate expert is bordering on wilful ignorance: https://www.inverse.com/article/7154-admitted-climate-change...

You really need to get your feet wet in this and read the actual research rather than look at people on the periphery that satisfy your biases.

[thrw_skpt]

I'm not sure why you rush to dimiss me like that. The question was "what would make you believe that AGW is real", and I mentioned that the climate models should be falsifiable. We know climate models cannot predict the weather beyond 2 weeks or so, but climate scientists claim that this is not their point. Fine, it's not their point. Then how do I know that this black box is correct, besides peer review? A model should state: X should happen (where X was not used in the calibration). Until yesterday I knew of only 2 such predictions: a periodic climatic phenomena similar to El Nino [1] (where the result is mixed) and the global temperature changes following the Pinatubo eruption [2] (where the result looks promising).

I didn't read your link where you say the models are performing very well, but I'll do it. Thanks.

Elsewhere in this thread, you resort to a bit of lower argumentation tactics ("supposed MIT PhD"). May I suggest you read Paul Graham's essey on desagreements [3] ? In return, here's a bit of mea culpa for my facile attack that the quoted very long life of the CO2 is only the result of a change of definition: while technically I was right, the definition change is one in good faith, and my critique was not.

[1] https://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch8s8-4... [2] https://www.giss.nasa.gov/research/briefs/hansen_02/ [3] http://www.paulgraham.com/disagree.html

[Cretin2]

"I'm not sure why you rush to dimiss me like that." Perhaps you should re-read how you dismissed what I put forward and you will understand the favor I returned with supporting evidence and perhaps too much snark.

This comment touches on the ENSO topic you are referencing to and discusses falsifiability: https://www.skepticalscience.com/argument.php?a=308#101174

I'd be interested to know what you're reading that brought you these arguments as they seem to be targeting them. So it is evident that they are being passed around circles of skeptics (not saying deniers).

There's a big difference between a climate model and a weather model and I believe you're familiar with the differences between long term changes (climate) and short term ones (weather). Just like we can't predict the interaction of every atom in a balloon yet we can predict how they will act as a whole when inflating one.

"In return, here's a bit of mea culpa for my facile attack that the quoted very long life of the CO2 is only the result of a change of definition: while technically I was right, the definition change is one in good faith, and my critique was not."

Thanks, I guess....but you are not technically right. You completely altered the state of my argument. I wasn't talking about the average. 15-40% (depending on the IPCC emissions projection) of CO2 remains in the atmosphere for upwards of 1,000 years. If our projections of climate change are correct we're in very big trouble as we've already locked in a significant amount of warming.

Additionally, you should be looking at AR5's physical science basis files, not AR4's if you want to be following the state of the science 4+ years ago instead of 10+.

[thrw_skpt]

I guess I skipped one or two steps in my mea culpa, so I'll cover them here.

You posted this link https://www.skepticalscience.com/co2-residence-time.htm

In this link, after a short introduction, we learn that there are about 750 GT of CO2 in the atmosphere, and about 200GT enter and leave the atmosphere each year, which is about 27%. CO2 molecules are indistinguishable from one another (leaving aside the trace amounts of molecules that contains isotopes different from C12 and O16). A molecule produced by human emissions does not look in any way different from another CO2 molecule. Moreover, in no time all the anthropogenic CO2 is equally mixed in the rest of the CO2 (by diffusion). Because of that the proportion of CO2 that stays in the atmosphere for a given time follows an exponential law with a decay coefficient of -log(1-0.27)=0.19 (see note). So out of all the CO2 in the atmosphere at a given time, only 83% stays there for 1 year, only 15% for 10 (uninterrupted) years, and only 5.6*10^(-9) after 100 years. And this is true both for all the original CO2 as for the anthropogenic CO2.

Now, if you change the definition of what it means for CO2 to remain in the atmosphere, then you get the long life you mentioned, but you do need to change that definition.

And this has nothing to do with averages vs medians or percentiles or other statistical concepts (which by the way, I am very familiar with).

(note) I'm skipping another step there, how to go from indistinguishability of CO2 to the exponential law, but if you want me, I can fill that in too.

[Cretin2]

Anthropogenic CO2. I thought that was apparent. Naturally emitted CO2 emissions are relatively constant and balanced over the last several hundred years, anthropogenic CO2 is not. Therefore as we continue to produce excess CO2 which cannot be absorbed by the system it results in excess CO2 which is not removed for upwards of 1000 years. We're removing sequestered CO2 and putting it in the atmosphere. It's not that complex.

From the same article I posted and you referenced:

"Dissolution of CO2 into the oceans is fast but the problem is that the top of the ocean is “getting full” and the bottleneck is thus the transfer of carbon from surface waters to the deep ocean. This transfer largely occurs by the slow ocean basin circulation and turn over (*3). This turnover takes 500-1000ish years. Therefore a time scale for CO2 warming potential out as far as 500 years is entirely reasonable."

You stated: "Because of that the proportion of CO2 that stays in the atmosphere for a given time follows an exponential law with a decay coefficient of -log(1-0.27)=0.19" this was not in the article. You're applying equations which are not appropriate to the system.

To repeat: https://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_Cha... rather than make up equations and argue with me about the minutia you really need to take some time and understand the physical science basis as explained by experts.

Within a thousand years, the remaining atmospheric fraction of the CO2 emissions (see Section 6.3.2.4) is between 15 and 40%, depending on the amount of carbon released (Archer et al., 2009b).

Again....I'd be interested to know what you're reading that brought you these arguments as they seem to be passed around circles of skeptics (not saying deniers).

[thrw_skpt]

> "You're applying equations which are not appropriate to the system."

Why are you saying this? Because it's not in the paper you linked? Are you sure that equation is not appropriate, and if so, because you know of an argument, or because you believe some expert?

On my side, I'm not reading things that circulate in some "circles". I'm just a guy who's curious about climate change, but who is not an expert. But I have a strong math and science background, and I can follow pretty much any scientific argument.

That being said, I'm faced with this conundrum: supposedly 97% of experts agree on a topic. The result of their agreement happens to be the result that brings in more funding for their research. There is an obvious conflict of interests. But this conflict in itself doesn't mean the consensus is wrong.

So, I'm trying to inform myself and reach a conclusion. I use both scientific reasoning and non-scientific heuristics.

Non-scientific heuristics are like this: Nate Silver (the guy behind the 538 blog) explains how he used statistics to get to the conclusion that climate change is real and is caused by the anthropogenic CO2. This sways me a bit towards believing the consensus. Freeman Dyson says the models fail to capture clouds. This sways me a bit in the opposite direction.

As for the scientific reasoning, it goes something like this. I get the general idea about CO2 absorbing the infrared radiation coming from the ground and therefore trapping some extra heat in the atmosphere. But CO2 is only 400 ppm, it's a very tiny part of the mass of the atmosphere. The youtube videos that you see with a bottle full of air and a bottle full of CO2 and how they heat up under a lamp are not very relevant. In the real world we are talking about an increase from 250 ppm to 400 ppm, not from 250 ppm to 100%. So the argument needs to be a bit more complex, and the IPCC report goes in more details. Following the details shows me they are thoughtful, and it's not junk science, so it swings me a bit towards the consensus.

But something is missing. Maybe you can fill it in, considering that you read a lot about these things. And it would honestly be appreciated (and by the way, you seem to be quite prejudiced against me, please give me a bit of benefit of the doubt).

Here's what's missing (imho). Bear with me, the story is a bit long. We are fortunate to live in a world with a lot of water. Water is special for a lot of reasons, but one absolutely remarkable property of water is that its specific heat exceeds by leaps and bounds the specific heat of any other substance that shows up in any abundance in our environment (e.g. at room temperature you need 4.2 Joules to warm up 1g of water by 1 deg Celsius, only 2.4 J for 1g of ethanol, and 1.0, 0.9 and 0.8 for air, O2 and CO2 respectively). But the truly astonishing number is the specific latent heat of vaporization for water, which is 2265 J/g. This exceeds any other specific latent heat for any other substance for any phase change by a very large amount (on a tangent note, this is what allows warm-bodied animals to keep their temperature constant, or put it another way, without this little curious property of water, humans would not exist).

There are about 750 GT of CO2 in the atmosphere (all gaseous) and about 13000 GT of water (both liquid and gas). Now the typical energy balance equation described in the IPCC report tells you how this water absorbs and re-emits radiation and in what spectrum and in what amount. But the missing piece is this: by far most of the radiation is absorbed and released by water upon the change of phase, i.e. when it evaporates from the oceans and then when it condenses in the clouds (before it falls downs as rains). When the water condenses in the clouds it must release that tremendous amount of energy I mentioned above (2.2 kJ per gram). It can do that in 2 ways: it heats the surrounding atmosphere (but that can't absorb much because of the other constants I mentioned, the 1.0 J/g/K for air, which is a puny number applied to a very rarefied substance) or it radiates. From the radiation, half points down, but half points up, towards space. To me this way of releasing energy in space should be by far and away the main way of the planet to get rid of extra heat.

Can you point me in the IPCC report where this heat enters in the heat balance of the atmosphere? I looked for it, and I didn't find it.

(PS I didn't read this thing anywhere, it's my own thinking)