5 ms·

There is definitely no shortage of doomsday climate models. CREDIBLE models is a different story. Look back at ones from 20+ years ago to see what they predic

by skrowl 9y ago

There is definitely no shortage of doomsday climate models. CREDIBLE models is a different story. Look back at ones from 20+ years ago to see what they predicted would be happening by now. It's pretty funny actually.

jjoonathan 9y ago
The models from 20 years ago overshot by several confidence intervals because they underestimated mixing the deep ocean. "The barrel is bigger than we expected" doesn't make the rising water in the barrel any less concerning, but it's not the triumph of foresight that you seem to imply.
- Banthum 9y ago
  Grandparent didn't imply it was a triumph of foresight, but rather a failure of foresight. I think that's what he's saying - a general point that people's understanding of climate (and thus predictions about it) are poorer than commonly believed.
  - marvin 9y ago
    Well, one day we might realize that we underestimated some critical aspect of climate change. Having overestimated it in the past is not an argument for relaxing today, and is certainly not a laughing matter.
johndevor 9y ago
Are there any models that predict accurately backwards?
- jjoonathan 9y ago
  All of them, because that's how you build models? Or do you mean something different?
  - herbst 9y ago
    Pretty sure he ment modern models that prove to be more right than others using past data. Interesting question imo
    - antishatter 9y ago
      I mean per the other response that is how you build models like this aka yes, all of them. Source: Am a Statistician edit: that doesn't mean they are correct going forward necessarily and most of the doomsday models I've seen are simulations that run thousands of times and a very small number of the simulations predict doom and a very small number predict no effects. The average of these expiriments is often the most likely scenario but doesn't really make headlines.
ioioio8908 9y ago
So will the models of today be as "off" in 20 years? We've come a long way in being able to collect and rapidly analyze large data sets. Doesn't seem like a proposition that holds.
sulam 9y ago
I don't need models when I have the historical record. The historical record says mean sea level is going to be hundreds of _meters_ above current levels in the not-too-distant future.
- pdeuchler 9y ago
  This is why people don't listen to the scientists, because absurd FUD like this gets spread and it discredits the entire movement. Even the most doomsday predictions are on the order of inches, maybe over a foot in the next 50 years. Such a rise would still be incredibly devastating, don't get me wrong, but it would take about a hundred years of a completely runaway warming cycle to raise the seas a single meter, much less hundreds.
  - sulam 9y ago
    I'm quite serious about the historical record. This is not FUD, this is data. The historical record shows that the last time atmospheric CO2 concentration was at the level we are at currently, several things were true. 1) temperatures were 4-5C higher. 2) there was no permanent surface ice anywhere on the planet as far as they can tell. 3) mean eustatic sea level was anywhere from 50 to 200m above current levels. http://onlinelibrary.wiley.com/doi/10.1029/2008PA001615/full http://onlinelibrary.wiley.com/doi/10.1029/2008PA001615/full Keep in mind, it's not just melting you need to figure in, there's also the thermal expansion of water. Also models do not currently project the Antarctic losing all of its ice, yet this is what the historical record suggests is likely. The models also do not account or undercount the contribution of non-anthropogenic forcing factors such as the one this article refers to -- they assume that _we_ are the main feedback loop, and yet there is evidence that we have entered a regime where we could reduce emissions to zero and the non-anthropogenic feedback would continue to add CO2 and methane to the atmosphere at a rate equal to or exceeding our current emissions. I believe the main reason you aren't hearing things like this is because scientists are picking their most defensible claims because they know that they will be hounded by climate change deniers. They are not talking about their worst fears, for worry of being labeled FUD.
    - 9y ago

by skrowl 9y ago

jjoonathan 9y ago

The models from 20 years ago overshot by several confidence intervals because they underestimated mixing the deep ocean. "The barrel is bigger than we expected" doesn't make the rising water in the barrel any less concerning, but it's not the triumph of foresight that you seem to imply.

Banthum 9y ago
Grandparent didn't imply it was a triumph of foresight, but rather a failure of foresight. I think that's what he's saying - a general point that people's understanding of climate (and thus predictions about it) are poorer than commonly believed.
- marvin 9y ago
  Well, one day we might realize that we underestimated some critical aspect of climate change. Having overestimated it in the past is not an argument for relaxing today, and is certainly not a laughing matter.

johndevor 9y ago

Are there any models that predict accurately backwards?

jjoonathan 9y ago
All of them, because that's how you build models? Or do you mean something different?
- herbst 9y ago
  Pretty sure he ment modern models that prove to be more right than others using past data. Interesting question imo
  - antishatter 9y ago
    I mean per the other response that is how you build models like this aka yes, all of them. Source: Am a Statistician edit: that doesn't mean they are correct going forward necessarily and most of the doomsday models I've seen are simulations that run thousands of times and a very small number of the simulations predict doom and a very small number predict no effects. The average of these expiriments is often the most likely scenario but doesn't really make headlines.

ioioio8908 9y ago

So will the models of today be as "off" in 20 years? We've come a long way in being able to collect and rapidly analyze large data sets. Doesn't seem like a proposition that holds.

sulam 9y ago

I don't need models when I have the historical record. The historical record says mean sea level is going to be hundreds of _meters_ above current levels in the not-too-distant future.

pdeuchler 9y ago
This is why people don't listen to the scientists, because absurd FUD like this gets spread and it discredits the entire movement. Even the most doomsday predictions are on the order of inches, maybe over a foot in the next 50 years. Such a rise would still be incredibly devastating, don't get me wrong, but it would take about a hundred years of a completely runaway warming cycle to raise the seas a single meter, much less hundreds.
- sulam 9y ago
  I'm quite serious about the historical record. This is not FUD, this is data. The historical record shows that the last time atmospheric CO2 concentration was at the level we are at currently, several things were true. 1) temperatures were 4-5C higher. 2) there was no permanent surface ice anywhere on the planet as far as they can tell. 3) mean eustatic sea level was anywhere from 50 to 200m above current levels. http://onlinelibrary.wiley.com/doi/10.1029/2008PA001615/full http://onlinelibrary.wiley.com/doi/10.1029/2008PA001615/full Keep in mind, it's not just melting you need to figure in, there's also the thermal expansion of water. Also models do not currently project the Antarctic losing all of its ice, yet this is what the historical record suggests is likely. The models also do not account or undercount the contribution of non-anthropogenic forcing factors such as the one this article refers to -- they assume that _we_ are the main feedback loop, and yet there is evidence that we have entered a regime where we could reduce emissions to zero and the non-anthropogenic feedback would continue to add CO2 and methane to the atmosphere at a rate equal to or exceeding our current emissions. I believe the main reason you aren't hearing things like this is because scientists are picking their most defensible claims because they know that they will be hounded by climate change deniers. They are not talking about their worst fears, for worry of being labeled FUD.
  - 9y ago