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Comment by raarts | Hacker News Reader

Well, I'm with you on sea level rise. I live in The Netherlands. Big part of our country is below sea level, millions of people actually. Recently Deltares, the body that advises the government on the height of our dikes released a 187-page report on sea level rise. Using the newest methods, they found that sea level has been rising at a constant rate (1.8mm/yr) for > 125 years now, and the sea level rise is NOT accelerating. I trust these people, since they are responsible for millions of lives.

Of course IPCC climate models are projecting acceleration, but those are just models. And past sea level rise acceleration projections have obviously been wrong so far.

I clearly remember over the course of my life reading about climate catastrophes, scientists being in consensus about it, it never came true, and I don't believe it now.

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You need to read the report more closely. First, it describes only the Dutch sea level rise, not the global sea level. Second, the most important reason that the sea level rise is that "the Netherlands is located in one of the least affected areas [of sea level rise] in the world. 9cm/century [of sea level rise] has not influenced the Netherlands, but has been observed around the equator" [1, from the summary]

[1] The report is here (in Dutch) https://www.deltares.nl/app/uploads/2019/03/faq-zeespiegelmo...

Yes, I've had that comment more often. My standard answer is that if sea level rise is accelerating somewhere on the planet, it should be accelerating everywhere. The sea level rise itself may differ per location, but logic dictates that an acceleration should be visible everywhere.

Note that sea level rise differs across the globe for many reasons, land sinking being one of them. For example, sea levels are dropping in Sweden, because the land is rising.

> if sea level rise is accelerating somewhere on the planet, it should be accelerating everywhere.

If you mean "accelerating upwards" then it is completely wrong. Sea level gets lower near large icebergs (e.g. the arctic). As the ice from the pole melts, the gravitational pull of the ice mass decreases and water is displaced to areas further from the pole.

As for your Sweden comment, I don't see how it is relevant. Please explain

I said 'sea level rise', not 'sea level'.

Sweden was just an example of a place where sea level is dropping.

Maybe I'm confused with what you're saying, please correct me where I misinterpret what you mean.

On a global scale, the sea-level is rising [1] and the sea-level increase is itself increasing (i.e. accelerating). This can also be seen in [1]. That does NOT mean that the change is uniform over the globe. You can check your locale here [2] (and confirm that Sweden's sea level is getting lower, the Netherlands slightly rising).

Globally, sea level rise IS accelerating [3].

Coming back to your claim that "if sea level rise is accelerating somewhere on the planet, it should be accelerating everywhere". Please explain why there could not be some (the Netherlands? hypothetical?) place where the the sea level rise does not increase even if more water is added to the system? This IS possible but the water must go somewhere else, i.e. the acceleration will be stronger in other regions (for example, Manilla).

[1] https://climate.nasa.gov/vital-signs/sea-level/

[2] https://tidesandcurrents.noaa.gov/sltrends/sltrends.html

[3] https://www.nasa.gov/feature/goddard/2018/new-study-finds-se...

You are confusing 'sea level rise increasing' with 'sea level rise increase acceleration'. Of course when a lot of water enters the ocean sea level rises everywhere. The amount to which it rises may not be the same everywhere, for example due to gravity differences. But as far as the 'acceleration of sea level rise' is concerned, that has to be visible everywhere.

An example. Suppose due to melting ice sea level rises 1 mm at the Dutch coast. Let's entertain the possibility that in Australia this results in 1,1 mm. Let's say this happens every year. Eventually this correlation will break, but for the sake of argument let's assume it doesn't. Now, when ice starts melting faster and faster, the sea level rise at the Dutch coast grows to 1.5 mm each year. This is sea level rise accelerating. Now, it is very unlikely that the rise in Australia stays at 1.1 mm each year and will not accelerate. That is why I say that if sea level rise is accelerating, it should show up every where. Hence if the rise isn't accelerating on the Dutch coast, it isn't accelerating anywhere.

Sea level rise isn't the same everywhere, but acceleration of that yearly rise should show up everywhere in some form.

Thank you for expanding on your thoughts. I now understand what you mean, however, I do believe you are wrong. Look at source [3] above. Sea level rise is accelerating globally. The effects are different locally.

A later study by (former IPCC) Dr Judith Curry has gone more into this [1]. And the report I referenced was even later. The comments on that page BTW make abundantly clear that scientists do not agree at all that the sea level rise is accelerating, and even if it is, if it's more than a minute amount. Most of the rise graphs focus around satellite measurement starting from 1993 which seem to show 3mm/year rise, and attaching these number to the graphs of sea level tide gauges is heavily disputed as scientific heresy. Additionally to get to that 3mm the satellite measurements had to be corrected, an action which was explicitly rejected by the recent Deltares report I referenced. So, whatever people may think, acceleration is not a fact, and even the scientists that believe it, think it's very small. It's the alarmist media that blow it up to huge proportions.

As a side note: I have been following climate news closely since a year now, and I have to say, I'm noticing strange patterns, in for example picking starting dates for graphs. Read for a recent example this article[2]. And I have noticed many occurrences of this, including from Goddard (part of NASA), NOAA, but also other institutions. This makes me suspicious.

In my own country the Dutch Royal Meteorological Institute, was accused of erroneously changing past temperature data - supposedly to correct for changed sensor setups, to make heatwaves in the first half of the 20th century disappear. I read that report, and it was very careful, and very thorough. But the Meteorological Institute refused to discuss it. It's these things that make me very suspicious. There are more examples, but I won't make this overly long.

So I would recommend looking really critically at any climate news, since in my experience most scientists do not agree on a lot of issues, despite claims to the contrary, and the subject is very heavily politicized.

[1] https://judithcurry.com/2018/11/27/special-report-on-sea-lev... [2] http://coyoteblog.com/coyote_blog/2019/10/illustrating-the-c...

The climate news needs to be looked at with extreme caution, I agree. Newspapers tend to spin scientific reports in a specific direction (both "alarmist" and "denyist"). However, in general the scientific literature is very cautious, and presents models, measurements and conclusions along with their uncertainties and assumptions. The interpretation of these uncertainties and assumptions is often lost in translation when presented to the general public, which is a shame and should not be endorsed. From a PR perspective, it may be nice if the Meteorological institute(s) would give some public interview or explanation when doubts are cast on their work. The discussions get political really quickly, which leads to a blurring of the lines between what the facts are and what (politicians) suggest the solutions should be to curb carbon emissions. This needs to end. Unfortunately, we are still in the situation where people outright deny the human role in climate change and politicians on the "denier" side of the spectrum abuse this to continuously cast doubt on whether any action is required at all.

That being said, you claim: "the satellite measurements had to be corrected, an action which was explicitly rejected by the recent Deltares report I referenced" but I couldn't find it in the report. The report (section 6.9) says [rough translation]: "The trend between satellite measurements and tide gauges [in the Netherlands] shows some agreement, along with their standard errors." and later "[..] satellite data are a less suitable source of deriving sea level rise". Note that this last quote should be interpreted in the Dutch sea level context, not the global context.

> It's the alarmist media that blow it up to huge proportions.

Agreed. That needs to stop.

> I'm noticing strange patterns, in for example picking starting dates for graphs

This, if true, is bad and needs to stop. It is the same behavior as the "deniers" have used for years (for example, the "no warming since 1998" meme).

I just noticed that you linked the summary of the report, the actual report is here: https://www.deltares.nl/app/uploads/2019/03/Zeespiegelmonito...

The researchers state (page 68 - my translation): "We don't see the worldwide acceleration observed by Nerem et al. (2018), within the 1993-2017 record. A correction for the eruption of the Pinatubo and El Niño – Southern Oscillation (ENSO) was needed to find that acceleration. These corrections we do not apply in the sea level monitor."

I must say I'm currently on the fence about the role of CO2 in global warming. I've read enough to confidently say that the consensus claimed by the media is not there, so I'm not done reading yet.

It was my mistake to link to the summary, I was actually referring to the full report in the comments before.

As for your quote, it needs to be read in the context of the full paragraph. Its written sloppily, but a better phrasing would be: "We don't see the worldwide acceleration observed by Nerem et al. (2018) in the Netherlands' coast area, within the 1993-2017 record". I.e. they are saying the global trend is not the same as the local (Dutch) trend. Perfectly reasonable.

> I must say I'm currently on the fence about the role of CO2 in global warming.

Well, I could imagine your doubts about sea level rise because they are difficult and uncertain. But there is absolutely no scientific doubt about the role of CO2 in global warming. In fact, CO2 as a control knob of the climate is the only way to explain climatic variations observed in (at least) the past 500 million years. What is uncertain is the predictions because they are influenced by action taken to curb emissions etc.

There is a great video series on YouTube by "potholer54" that shows the scientific evidence for it better than I can. The first video is only 10 minutes and addresses the general points rather well. https://www.youtube.com/watch?v=52KLGqDSAjo&list=PL82yk73N8e...

> CO2 as a control knob of the climate is the only way to explain climatic variations observed in (at least) the past 500 million years

I think you may now be stretching it: https://miro.medium.com/max/1320/0*3Vm0copgT8K-pcRm.gif No relation between temperature and CO2 levels.

Also, it's rather unlikely that for a system as complex as the climate there would be only one control knob.

I've seen all of potholer54's videos.

1) Your meme-image does not show there is no relation. In fact, the source of one of the lines in the image is by Berner [1] which states (p. 201): "This means that over the long term there is indeed a correlation between CO2 and paleotemperature, as manifested by the atmospheric greenhouse effect." The source of your image directly contradicts your claim.

2) RE "unlikely that [...] there would be only one control knob": I never said there was only one. I said it was a control knob. And it is in fact the most important one (but not the only one) [2].

3) RE "I've seen all of potholer54's videos.": I think you need to watch them again.

[1] "Geocarb III: A Revised Model of Atmospheric CO2 over Phanerozoic Time ", http://www.ajsonline.org/content/301/2/182

[2] "Atmospheric CO2: Principal Control Knob Governing Earth’s Temperature", https://science.sciencemag.org/content/330/6002/356

[3] As a side note: your image has no x- and y-axis scales. If you want to spread misleading images, at least use a better version (for instance, https://abruptearthchanges.files.wordpress.com/2019/07/no-lo...)

The only thing you can say about the correlation in Geocarb II (my graph) and Geocarb III (your graph) is that 500 million years ago CO2 was 6000ppm and temperature 25ºC. Today CO2 is 410ppm, and temp 16ºC. That's it. So you could say there's a long term trend. But both graphs show wildly diverging lines between those points, in fact it was only during a few percent of the total time that the temperature rose when CO2 levels rose. This does not look like CO2 is mainly controlling the climate at all. So there is my problem.

There are more problems, like the multiple periods of warming and cooling in the last 1000 years, that were just as bad or worse as what we're in now, but without human CO2. Like the fact that in the past CO2 followed temperature instead of preceding it (and the Milankovitch 'explanation' is not convincing at all), and like the fact that in recent years records are being shattered for cold weather all over the globe. And the media doesn't report about that.

This thing about the climate is that everybody tells me to educate myself, and when I did, it only raised more questions.

I am glad you're willing to educate yourself. I hope to give you at least a starting point and will try to address the points you made.

1) Regarding the correlations: The reason why you don't "see" the correlation (i.e. the lines don't perfectly overlap) if you plot CO2 and average global temperature is because there are other effects that obscure the correlation. For example, on the scales of 500 million years, the power coming from the sun (solar luminosity) has increased [1]. Milankovitch cycles are also important over longer timescales. Albedo changes of Earth's surface, etc. I have already cited the principle control knob paper. If you don't agree with the results, we can discuss that but, if so, please give some arguments instead of "I don't believe it".

2) "CO2 lags temperature": this is true in some cases. Vostok ice core is often cited and indeed the authors point to a ~1000 year difference between CO2 and temperature [2]. A more recent analysis [3] goes into more detail on a global sample. They find that on average, CO2 leads temperature but in the southern hemisphere, temperature leads CO2. This lag can be explained by ocean circulation changes.

3) "multiple periods of warming and cooling in the last 1000 years, that were just as bad or worse as what we're in now": A landmark paper was released this year reconstructing the global temperatures in the last 2000 years [4] and they concluded the current warming is global and warmer than ever. Other warm periods in the last 2000 years were simply a) not as warm AND/OR b) not global. One image says it all [5].

4) Record cold not reported? I get a lot of search results from mainstream outlets when searching [6]. Of course, one cold/warm year does not disprove/prove global warming, but you know that. Also, weather and climate are different but you also know that. Popsci did an article explaining how this cold can be interpreted [7].

[1] For a short explanation, see Wikipedia: https://en.wikipedia.org/wiki/Solar_luminosity

[2] "CO2‐climate relationship as deduced from the Vostok ice core: a re‐examination based on new measurements and on a re‐evaluation of the air dating", https://onlinelibrary.wiley.com/doi/abs/10.1034/j.1600-0889....

[3] "Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation", https://www.nature.com/articles/nature10915

[4] "No evidence for globally coherent warm and cold periods over the preindustrial Common Era", https://www.nature.com/articles/s41586-019-1401-2"

[5] Image from [4] https://media.springernature.com/full/springer-static/image/...

[6] https://duckduckgo.com/?q=record+cold+2019

[7] https://www.popsci.com/cold-weather-climate-change/

> I trust [Deltares], since they are responsible for millions of lives.

OK, so do so.

https://www.deltares.nl/en/blog/the-battle-of-engineers-agai...

> Climate change is happening right now and at a frightening speed, especially in the Arctic. To underpin the need for action, I share three wake-up calls...

> We can’t afford to ignore the warning signs. The longer we wait, the harder it will be to get climate change under control. After long negotiations, world leaders have agreed on action at the Paris climate summit. Now it’s up to the engineers to develop ambitious plans and innovative solutions.

You are quoting a blog entry from 2016. The report I was referring to was from march 2019. They debunked their own blogpost.

In another comment, someone pointed out issues with your understanding of that report, which you replied to with basically "well I don't believe that part". As such, I'm not inclined to credit your claim they "debunked" this. You're welcome to cite an updated statement or blog post saying so, though.

This is just a bizarre exchange, (which I'm obviously changing to make people look silly, but I'll assume it reflects things accurately):

raarts: the official report by people with the expertise to measure this says X.

itcrowd: yea but here's someone's personal opinion from some blog hosted by that organization

raarts: sure, but that's an old blog post, and also it's just a blog post?

ceejayoz: I found some other post you made so I don't have to care what the official report says. I can assume you are lying because it is convenient. In the meantime, I won't hold any posts I agree with to any such standard.

Except the official report doesn't say what's being claimed here. If they've decided climate change is debunked, that'd be worthy of at least a new blog post.

It's pointed out at https://news.ycombinator.com/item?id=21313203 that /u/raarts misread that section.

For others who arrived here, it was not 'pointed out' that I read it wrong, it was suggested that I read it wrong. The discussion continued from there, and I think I explained my point quite clearly, and I definitely did not read it wrong. I still maintain sea level rise is not accelerating and my logic behind that was not proven wrong. Instead my discussion partner started pointing to other sources.

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