9 ms·

Please don't take this as a denial of climate change, it is an honest question. How do scientists learn the levels of ozone, aerosols, green house gases, and th

Please don't take this as a denial of climate change, it is an honest question. How do scientists learn the levels of ozone, aerosols, green house gases, and the other data points going so far back at a global scale? Is the data from before the latter half of the 20th century spotty? If so, why is it considered good enough to use in a context of scientific research where quality and correctness of data is paramount?

ahallock 11y ago
The fact that you have to have a disclaimer up front makes me sad.
- reitanqild 11y ago
  Me to. Way too many people, on both sides, will attack anyone who comes across as unsupportive. Especially when it happens on HN and other sites that I come to to learn and discuss.
- talmand 11y ago
  It's a serious problem in multiple areas in society these days; the inability to ask simple questions that may go against the "accepted" narrative without being personally attacked. Science, religion, politics, sports, it's everywhere. It's a seriously sad state of affairs, but nothing new really, if you think about it. The reach of modern communications has inflated the problem in my opinion.
  - npsimons 11y ago
    Here's the thing: honest enquiry is something that should be encouraged. Sea-lioning[1], JAQing off[2] and Gish gallops[3] should not. When you are buried to your eyeballs in bullshit, it's hard to see who is really someone willing learn, and who is just shoveling on more. [1] - http://simplikation.com/why-sealioning-is-bad/ http://simplikation.com/why-sealioning-is-bad/ [2] - http://rationalwiki.org/wiki/Just_asking_questions http://rationalwiki.org/wiki/Just_asking_questions [3] - http://rationalwiki.org/wiki/Gish_Gallop http://rationalwiki.org/wiki/Gish_Gallop
    - Uhhrrr 11y ago
      The problems are 1) You can't tell whether someone is "just asking questions" in good faith or not. 2) Dismissing a horde of people all raising the same problems with one's beliefs as "sealions" is a tempting shortcut to actually examining one's beliefs, which might in fact be wrong.
    - EdiX 11y ago
      It boggles my mind that people use the term sealioning unironically. How can it possibly be that a sensible person thinks it's ok to make a hateful statement in a public place and when someone asks clarification about it they are the harassers?! You are not a priest preaching to the ignorant congregation, if you don't want to deal with the bullshit get off the fucking podium.
      - cactusface 11y ago
        Here's my sealion of a question. What parts of climate change research are actually backed up by the scientific method (experiments with falsifiable hypotheses and all that) and what parts are more akin to natural history or something else? To clarify, I believe humans caused the problem (it appears that stating this makes people like you more, which is weird, but ok) but I cringe every time I hear the word science attached to the debate. Is it like a social science? I think someone told me that we know for sure that greenhouse gas emissions cause ozone depletion but I can't remember anymore. What is the actual hard science here?
        EdiX 11y ago
        >What parts of climate change research are actually backed up by the scientific method (experiments with falsifiable hypotheses and all that) and what parts are more akin to natural history or something else? I do not generally get involved in the climate change debate because it has multiple problems: it happens on scales (both time and space) that humans have difficulty observing, it is about a system with lots of feedback that could very well behave chaotically, direct observations of the phenomenon are limited compared to its timescale, experts of the subject are operating under perverse incentives, it is highly politicized and almost everything that's easy to read about the subject is blatant propaganda (see all the climate change denialist posted in this thread as well as the OP). Your question is hard to answer because it assumes there is a shared and agreed upon definition of the word "science" that can be used to determine with certainty wethere something is science or not. > Is it like a social science? I think someone told me that we know for sure that greenhouse gas emissions cause ozone depletion but I can't remember anymore. What is the actual hard science here? I think it is in better shape than the average social science, the greenhouse effect and the ozone depletion are two separate phenomena, this [1] is the experiment that explains how the greenhouse effect works, the wikipedia page about ozone depletion explains the chemical reactions that lead to that. [1] https://en.wikipedia.org/wiki/Svante_Arrhenius#Greenhouse_effect https://en.wikipedia.org/wiki/Svante_Arrhenius#Greenhouse_ef...
twohlix_ 11y ago
They don't for aerosols/ozone past the 50s I dont think. But carbon/methane/NO/etc... they get from ice samples that have trapped air bubbles from quite a long time ago. They also take a ton of samples from ice cores and the data is reproducible both in the north and south poles. I believe temperature is also learned from the ice samples.
adaml_623 11y ago
Ice cores. Google it.
ageofwant 11y ago
Its either directly measured or inferred. Ice cores, lake bottom cores, old wood cores. The error bars are wider for some, I'm sure, but that's accounted for in the models, to degrees of course.
paulhauggis 11y ago
I also question how we know the difference between nature/cycles and man-made pollution. Here is a good example: https://en.wikipedia.org/wiki/Little_Ice_Age https://en.wikipedia.org/wiki/Little_Ice_Age "Several causes have been proposed: cyclical lows in solar radiation, heightened volcanic activity, changes in the ocean circulation, an inherent variability in global climate, or decreases in the human population." It seems we don't even know how the little ice age happened. How do we know these same forces aren't changing our environment now? We've been having all these strange temperatures lately and also this: http://www.independent.co.uk/life-style/gadgets-and-tech/news/huge-solar-storm-hits-earth-power-grid-and-gps-could-be-disrupted-but-auroras-might-be-seen-10338332.html http://www.independent.co.uk/life-style/gadgets-and-tech/new... The problem is that it's too political now. When claimed scientists are coming out and saying the science is "settled", I know we have a problem. Science is never really settled.
- paulhauggis 11y ago
  I bring up some simple questions and I am immediately silenced. I guess I didn't realize HN was anti-science and anti-intellectual.
  - jessaustin 11y ago
    http://www.paulgraham.com/say.html http://www.paulgraham.com/say.html
    - davidgerard 11y ago
      That essay is not, however, an invitation to the Galileo gambit.
      - jessaustin 11y ago
        Given that the essay links approvingly to Crichton's Aliens Cause Global Warming address, I think you might understand it better if you read the whole thing again.
  - 11y ago
hackuser 11y ago
Good question. I know of one way, which is to look at sedement and other physical evidence that is laid down gradually over time. For example, tree rings (of trees hundreds or thousands of years old, or maybe even petrified trees) and ice cores (for example, from Antartica; the chemical composition of the ice and the air trapped in it depends on the prevailing environment). As I understand it, your question has received much attention over the years and these techniques are mature and well-developed. To understand these issues and much more, I highly recommend spend a little time on the IPCC reports: https://news.ycombinator.com/item?id=9772353 https://news.ycombinator.com/item?id=9772353
vilda 11y ago
They use so-called "proxy data". You measure something else that has been accumulated and preserved over time and that somehow correlates. You have to create a model, fit it so it correlates with recent measures and you are done. Level of oxygen for example can be estimated from layers of ice. Mann used tree slice(s) for temperature estimation. There's a lot of problems with proxy data and their models and there is a lot of space for scientific misdemeanor. Some journals recently started to require a full disclosure of all data and models on which they base their claims, which - surprisingly - isn't always the case. As more data is gathered over time some models need to be adjusted. How much they need to be adjusted reflects quality of the model.

ahallock 11y ago

The fact that you have to have a disclaimer up front makes me sad.

reitanqild 11y ago
Me to. Way too many people, on both sides, will attack anyone who comes across as unsupportive. Especially when it happens on HN and other sites that I come to to learn and discuss.
talmand 11y ago
It's a serious problem in multiple areas in society these days; the inability to ask simple questions that may go against the "accepted" narrative without being personally attacked. Science, religion, politics, sports, it's everywhere. It's a seriously sad state of affairs, but nothing new really, if you think about it. The reach of modern communications has inflated the problem in my opinion.
- npsimons 11y ago
  Here's the thing: honest enquiry is something that should be encouraged. Sea-lioning[1], JAQing off[2] and Gish gallops[3] should not. When you are buried to your eyeballs in bullshit, it's hard to see who is really someone willing learn, and who is just shoveling on more. [1] - http://simplikation.com/why-sealioning-is-bad/ http://simplikation.com/why-sealioning-is-bad/ [2] - http://rationalwiki.org/wiki/Just_asking_questions http://rationalwiki.org/wiki/Just_asking_questions [3] - http://rationalwiki.org/wiki/Gish_Gallop http://rationalwiki.org/wiki/Gish_Gallop
  - Uhhrrr 11y ago
    The problems are 1) You can't tell whether someone is "just asking questions" in good faith or not. 2) Dismissing a horde of people all raising the same problems with one's beliefs as "sealions" is a tempting shortcut to actually examining one's beliefs, which might in fact be wrong.
  - EdiX 11y ago
    It boggles my mind that people use the term sealioning unironically. How can it possibly be that a sensible person thinks it's ok to make a hateful statement in a public place and when someone asks clarification about it they are the harassers?! You are not a priest preaching to the ignorant congregation, if you don't want to deal with the bullshit get off the fucking podium.
    - cactusface 11y ago
      Here's my sealion of a question. What parts of climate change research are actually backed up by the scientific method (experiments with falsifiable hypotheses and all that) and what parts are more akin to natural history or something else? To clarify, I believe humans caused the problem (it appears that stating this makes people like you more, which is weird, but ok) but I cringe every time I hear the word science attached to the debate. Is it like a social science? I think someone told me that we know for sure that greenhouse gas emissions cause ozone depletion but I can't remember anymore. What is the actual hard science here?
      - EdiX 11y ago
        >What parts of climate change research are actually backed up by the scientific method (experiments with falsifiable hypotheses and all that) and what parts are more akin to natural history or something else? I do not generally get involved in the climate change debate because it has multiple problems: it happens on scales (both time and space) that humans have difficulty observing, it is about a system with lots of feedback that could very well behave chaotically, direct observations of the phenomenon are limited compared to its timescale, experts of the subject are operating under perverse incentives, it is highly politicized and almost everything that's easy to read about the subject is blatant propaganda (see all the climate change denialist posted in this thread as well as the OP). Your question is hard to answer because it assumes there is a shared and agreed upon definition of the word "science" that can be used to determine with certainty wethere something is science or not. > Is it like a social science? I think someone told me that we know for sure that greenhouse gas emissions cause ozone depletion but I can't remember anymore. What is the actual hard science here? I think it is in better shape than the average social science, the greenhouse effect and the ozone depletion are two separate phenomena, this [1] is the experiment that explains how the greenhouse effect works, the wikipedia page about ozone depletion explains the chemical reactions that lead to that. [1] https://en.wikipedia.org/wiki/Svante_Arrhenius#Greenhouse_effect https://en.wikipedia.org/wiki/Svante_Arrhenius#Greenhouse_ef...

twohlix_ 11y ago

They don't for aerosols/ozone past the 50s I dont think. But carbon/methane/NO/etc... they get from ice samples that have trapped air bubbles from quite a long time ago. They also take a ton of samples from ice cores and the data is reproducible both in the north and south poles. I believe temperature is also learned from the ice samples.

adaml_623 11y ago

Ice cores. Google it.

ageofwant 11y ago

Its either directly measured or inferred. Ice cores, lake bottom cores, old wood cores. The error bars are wider for some, I'm sure, but that's accounted for in the models, to degrees of course.

paulhauggis 11y ago

I also question how we know the difference between nature/cycles and man-made pollution. Here is a good example: https://en.wikipedia.org/wiki/Little_Ice_Age https://en.wikipedia.org/wiki/Little_Ice_Age "Several causes have been proposed: cyclical lows in solar radiation, heightened volcanic activity, changes in the ocean circulation, an inherent variability in global climate, or decreases in the human population." It seems we don't even know how the little ice age happened. How do we know these same forces aren't changing our environment now? We've been having all these strange temperatures lately and also this: http://www.independent.co.uk/life-style/gadgets-and-tech/news/huge-solar-storm-hits-earth-power-grid-and-gps-could-be-disrupted-but-auroras-might-be-seen-10338332.html http://www.independent.co.uk/life-style/gadgets-and-tech/new... The problem is that it's too political now. When claimed scientists are coming out and saying the science is "settled", I know we have a problem. Science is never really settled.

paulhauggis 11y ago
I bring up some simple questions and I am immediately silenced. I guess I didn't realize HN was anti-science and anti-intellectual.
- jessaustin 11y ago
  http://www.paulgraham.com/say.html http://www.paulgraham.com/say.html
  - davidgerard 11y ago
    That essay is not, however, an invitation to the Galileo gambit.
    - jessaustin 11y ago
      Given that the essay links approvingly to Crichton's Aliens Cause Global Warming address, I think you might understand it better if you read the whole thing again.
- 11y ago

hackuser 11y ago

Good question. I know of one way, which is to look at sedement and other physical evidence that is laid down gradually over time. For example, tree rings (of trees hundreds or thousands of years old, or maybe even petrified trees) and ice cores (for example, from Antartica; the chemical composition of the ice and the air trapped in it depends on the prevailing environment). As I understand it, your question has received much attention over the years and these techniques are mature and well-developed. To understand these issues and much more, I highly recommend spend a little time on the IPCC reports: https://news.ycombinator.com/item?id=9772353 https://news.ycombinator.com/item?id=9772353

vilda 11y ago

They use so-called "proxy data". You measure something else that has been accumulated and preserved over time and that somehow correlates. You have to create a model, fit it so it correlates with recent measures and you are done. Level of oxygen for example can be estimated from layers of ice. Mann used tree slice(s) for temperature estimation. There's a lot of problems with proxy data and their models and there is a lot of space for scientific misdemeanor. Some journals recently started to require a full disclosure of all data and models on which they base their claims, which - surprisingly - isn't always the case. As more data is gathered over time some models need to be adjusted. How much they need to be adjusted reflects quality of the model.