Even 50-year-old climate models correctly predicted global warming • Hacker News Board

Re: Even 50-year-old climate models correctly predicted global warming

#191

Post by jml7c5 » Thu, Dec 05, 2019, 2:55 AM UTC

jml7c5 wrote: post #29

I'm not sure if he'll pop in here, but one of the co-authors (Henri Drake) has a comment thread on /r/science if anyone wants to ask any questions: https://www.reddit.com/r/science/comments/e63ic5/of_17_clima... EDIT: Here is some of the code used in the paper: https://github.com/hausfath/OldModels Here is a blog post on the paper, written by one of the authors: http://www.realclimate.org/index.php/archives/2019/12/h…

A copy of the paper that's not trapped behind a paywall: https://pubs.giss.nasa.gov/abs/ha08910q.html

Re: Even 50-year-old climate models correctly predicted global warming

#192

Post by irq11 » Thu, Dec 05, 2019, 3:09 AM UTC

telotortium wrote: post #123

IanCal wrote: post #91

Earlier quoted context omitted.

Doesn't this partly fall into the weather Vs climate difference? I can't run fluid dynamics in my head but no matter how much you shake up the box once it's on the table I can say "I think the water/oil/honey will end up at the bottom". But also yes, it's complex, that's why independent groups dedicate huge amounts of time researching and building them and then models are compared against each other.

> Doesn't this partly fall into the weather Vs climate difference? I can't run fluid dynamics in my head but no matter how much you shake up the box once it's on the table I can say "I think the water/oil/honey will end up at the bottom". Not in the slightest. For example, the output of a numerically unstable [1] algorithm, run on 64-bit floats, can diverge arbitrarily from the output of the same algorithm run on rea…

This is not a rebuttal to the parent. They’re talking about stability of prediction of aggregate properties, and you’re fixating on numerical precision errors and algorithm bugs in particular implementations. The one has little to do with the other.

Numerical instability leads to obvious, wildly inconsistent errors. It isn’t subtle. Literally no climate simulations are going off the rails because of these kinds of first-year grad-student code problems.

Re: Even 50-year-old climate models correctly predicted global warming

#193

Post by jamez1 » Thu, Dec 05, 2019, 3:15 AM UTC

namirez wrote: post #73

ekianjo wrote: post #48

Where is the story hère though? So they looked retroactively and found some models in the past that fitted with current observations even though they had no clue that China would become such a powerful force in terms of CO2 emissions? If you run random models and wait long enough you will always be able to find at least one model that predicted the current observations. That does NOT mean the models were right, it me…

> even though they had no clue that China would become such a powerful force in terms of CO2 emissions I think you're making the same mistake that you're attributing to the story. It really doesn't matter what China does per se. The global energy consumption, roughly, follows a log-linear trend. If the energy comes from fossil fuels, the CO2 emissions would also follow the same trend [1]. It doesn't matter whether it…

There is no physical phenomenon that causes the log-linear trend, its just a model that happens to fit for a small select period of history. Moore's law isn't an actual law I hope you understand that..

Rising prosperity comes with rising energy consumption. If China didn't export so much it wouldn't be able to import the fuel that it used. Its dramatic rise was definitely not a given.

Re: Even 50-year-old climate models correctly predicted global warming

#194

Post by mturmon » Thu, Dec 05, 2019, 3:35 AM UTC

benmaraschino wrote: post #185

jointpdf wrote: post #172

Earlier quoted context omitted.

Simulation is one way to produce a numerical forecast, but the prediction of any forecast model would never be the result of a single simulation run. Model predictions are always (or should always) be reported as an expected value, or the average over many simulation runs. The expected value of a random variable (e.g. mode output) is probably the most fundamental concept in all of statistics/probability, and many min…

Agreed. The point of criticism that the authors didn’t include all relevant models is among the lowest of the low-hanging fruit I can imagine one picking. And while the process of peer review isn’t without its flaws, I can also imagine that fruit has long since been picked by the reviewers, who have far deeper knowledge of the published models than I or just about anyone else in this thread, save for the actual clima…

Thirded. The posting of climate-related stories on HN brings out a lot of un-informed skepticism. The resulting back-and-forth tends to crowd out everything else.

In many of these cases, it's clear that the commenters have done no background reading, and have no climate science background. Their comments thus consist of simple armchair speculation (your "lowest of the low-hanging fruit").

In these comments, I have found people with strong opinions on the lack of seriousness of climate science, who have no idea we have gravimetric measurements of ice sheet mass. This is a dataset going back almost 20 years that has revolutionized geoscience. HN commenters have expressed strong opinions about melting ice, with no knowledge of this data and what it means.

I have found people who think that climate science consists of having a stable of models each with a host of knobs, and the research method is to turn the knobs or choose new models until the results look dramatic enough to publish.

The gap between the firmness of these claims and the knowledge to back it up just boggles the mind.

The most basic step people could take to fix this is to read the executive summary of the IPCC AR5 report, or (even better/easier) the executive summary of the NCA (https://science2017.globalchange.gov). This report was specifically written by people who really know this stuff, for people like us.

Re: Even 50-year-old climate models correctly predicted global warming

#195

Post by virmundi » Thu, Dec 05, 2019, 3:43 AM UTC

refurb wrote: post #176

I’m confused as hell to be honest. A few years ago they said there was a global warming pause.[1]. They seemed so sure it was happening that Nature devoted a whole issue to it. Then they came back and said “actually it never happened”.[2] Shouldn’t it be pretty straightforward to tell whether there was warming or not? [1] https://www.nature.com/collections/sthnxgntvp [2] https://insideclimatenews.org/news/18122018/gl…

Not if they keep changing the data to fit a need. Check out Tony Heller https://www.youtube.com/playlist?list=UUprclkVrNPls7PR-nHhf1...

Re: Even 50-year-old climate models correctly predicted global warming

#196

Post by hatmatrix » Thu, Dec 05, 2019, 3:47 AM UTC

yters wrote: post #189

tzs wrote: post #101

Earlier quoted context omitted.

Those predictions were based upon projections that we would not address the growing levels of smog and other particulates, and the cooling effect from those would be larger than the warming effect from greenhouse gases. We did address smog. Without growing smog, those models predicted warming.

Would increasing particulates be an effective way to stop global warming?

That's one proposal for geoengineering (either sulfate particles in the stratosphere, or marine particles over the oceans). More for a "pause" or slow down rather than a solution to stop it.

Re: Even 50-year-old climate models correctly predicted global warming

#197

Post by mehrdadn » Thu, Dec 05, 2019, 3:48 AM UTC

DennisP wrote: post #158

ekianjo wrote: post #48

Where is the story hère though? So they looked retroactively and found some models in the past that fitted with current observations even though they had no clue that China would become such a powerful force in terms of CO2 emissions? If you run random models and wait long enough you will always be able to find at least one model that predicted the current observations. That does NOT mean the models were right, it me…

Whether or not China emitted lots of CO2 doesn't matter here. The old studies didn't predict how much CO2 the world would emit. They predicted how much the planet would warm, for various amounts of CO2 emissions. It turned out they were correct about that. Among the models this study looked at was Hansen's. That's the NASA scientist who testified about global warming to Congress in 1988. It'd be quite a coincidence i…

Thanks, I feel like I finally found a gem of a comment in the middle of all this heavy back and forth.

Re: Even 50-year-old climate models correctly predicted global warming

#198

Post by mistermann » Thu, Dec 05, 2019, 3:50 AM UTC

hcknwscommenter wrote: post #126

mistermann wrote: post #103

Earlier quoted context omitted.

> As noted in TFA, they looked at 17 forecasts from 14 models Pardon a little pedantry: >> The researchers compared annual average surface temperatures across the globe to the surface temperatures predicted in 17 forecasts. Those predictions were drawn from 14 separate computer models released between 1970 and 2001. In some cases, the studies and their computer codes were so old that the team had to extract data publ…

TFA article does say. They looked at 17 forecasts drawn from 14 models. You are the one who implicitly believes they are lying about that and only reporting 17 out of some huge unknown number. The reality is that the vast majority (>99%) of climate change research does not produce the type of forecast, or really any forecast at all, that one could do this analysis on. Therefore, the 17 forecast number is actually ver…

> TFA article does say.

It says something.

> They looked at 17 forecasts drawn from 14 models.

It does not say this. What you have written is your uncritical interpretation, what I wrote is a literal quotation, which allows for (satisfies) the conspiratorial possibility that I raised.

> You are the one who implicitly believes they are lying about that

You are speculating. Speculation is fine, but it's best to realize (and state explicitly) when you're doing it.

Know how I know you're speculating? Because while you only believe you can read my mind, I can actually do it, and I do not "believe they are lying". I was only pointing out that as written, they could be lying.

And I even told you the reason why I wrote that comment: "Articles written in this style provide rich fodder for conspiracy theorists..."

If you truly want to change minds, you might want to learn how the minds you want to change work. Go spend some serious time in conspiracy forums, I suspect you might learn something useful.

And rather than largely ignoring the actual words of someone who's trying to help out your cause, treating them as an enemy rather than someone who may have some insight you lack, it might be helpful to keep a more open mind. Perhaps if those with knowledge severely lacking in the mainstream discourse weren't rate limited, some here may find some new ideas to consider.

Re: Even 50-year-old climate models correctly predicted global warming

#199

Post by namirez » Thu, Dec 05, 2019, 3:54 AM UTC

jamez1 wrote: post #193

namirez wrote: post #73

Earlier quoted context omitted.

> even though they had no clue that China would become such a powerful force in terms of CO2 emissions I think you're making the same mistake that you're attributing to the story. It really doesn't matter what China does per se. The global energy consumption, roughly, follows a log-linear trend. If the energy comes from fossil fuels, the CO2 emissions would also follow the same trend [1]. It doesn't matter whether it…

There is no physical phenomenon that causes the log-linear trend, its just a model that happens to fit for a small select period of history. Moore's law isn't an actual law I hope you understand that.. Rising prosperity comes with rising energy consumption. If China didn't export so much it wouldn't be able to import the fuel that it used. Its dramatic rise was definitely not a given.

> There is no physical phenomenon that causes the log-linear trend, its just a model that happens to fit for a small select period of history.

Of course it's a model. Please look up the Kardashev scale and correlations that people have developed based on it [1]. The energy output is not necessarily coupled with the CO2 emission unless we burn fossil fuels to generate power.

[1] https://en.wikipedia.org/wiki/Kardashev_scale#Current_status...

Re: Even 50-year-old climate models correctly predicted global warming

#200

Post by pragmar » Thu, Dec 05, 2019, 3:54 AM UTC

yters wrote: post #189

tzs wrote: post #101

Earlier quoted context omitted.

Those predictions were based upon projections that we would not address the growing levels of smog and other particulates, and the cooling effect from those would be larger than the warming effect from greenhouse gases. We did address smog. Without growing smog, those models predicted warming.

Would increasing particulates be an effective way to stop global warming?

Definitely, there was an "albedo yachts" solution that was floated a while back. Basically kicking up mist from the oceans. It's all just theory, and the repercussions are probably not well understood, but the idea is out there and implementation would be relatively inexpensive.