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(New Scientist)   Another study shows that precise climate predictions are about as accurate as your local weatherman 's predictions of tomorrow's weather   (environment.newscientist.com) divider line 89
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700 clicks; posted to Geek » on 26 Oct 2007 at 11:48 AM (6 years ago)   |  Favorite    |   share:  Share on Twitter share via Email Share on Facebook   more»



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2007-10-26 11:34:14 AM
The reason lies with feedbacks in the climate system. For example, as the temperature increases, less snow will be present at the poles. Less snow means less sunlight reflected back into space, which means more warming.

These positive feedbacks accelerate global warming and also introduce uncertainty into estimates of climate sensitivity, say Gerard Roe and Marcia Baker of the University of Washington in Seattle.

As far as I can tell, there's nothing new here. All they appear to have to say is that global warming could be much worse than has been anticipated.

/digging for actual study instead of this empty blurb
 
2007-10-26 11:36:41 AM

Meanwhile

Planet's CO2 Production Surges
http://sciencenow.sciencemag.org/cgi/content/full/2007/1022/1

An international team of scientists has taken another look at how rapidly Earth's atmosphere is absorbing carbon dioxide (CO2)--the biggest greenhouse gas in terms of volume--and the news is not good: A high-flying world economy is pumping out the gas at an unprecedented rate. Current CO2 production is outstripping the best estimates used by modelers to predict future climate trends.
 
2007-10-26 11:52:43 AM
Chaos theory.

/that is all
 
2007-10-26 11:56:31 AM

OK, this headline and summary misrepresent the argument presented in this article

http://www.eci.ox.ac.uk/publications/downloads/frame07-sensitivity.pdf

This sensitivity of the results to prior assumptions shows that the real problem with the upper bound on climate sensitivity is not that it is high (in which case we could hope that more data will bring it down), but that it is controversial: Opaque decisions about statistical methods, which no data can ever resolve, have a substantial impact on headline results. All this would be very bad news if avoiding dangerous anthropogenic interference in the climate system required us to specify today a stabilization concentration of carbon dioxide (or equivalent) for which the risk of a dangerous level of warming is acceptably low. Fortunately, we do not need to.

In a nutshell, they are arguing that there are uncertainties about the worst climate change scenarios, but that doesn't change the fact that we need to reduce or CO2 emissions.
 
2007-10-26 12:00:49 PM
Conservationismistism is the tinfoil loinclothe ecologists wear to keep bees out of their mango-chutney.
 
2007-10-26 12:03:34 PM
Another study shows that precise climate predictions are about as accurate as the precise predictions your local weatherman 's predictions of tomorrow's weather

So pretty damn good, eh? Meterologist next-day forecasts are generally considered in the 90% range for accuracy. It's longer thna three-five days where it starts to get wooly.
 
2007-10-26 12:04:42 PM
I work in the predicting-the-future biz, so I am getting a kick out of these replies.

I loved the "35 point" refutation of Gore's film in one of yesterday's threads. Basically, it claimed that everything is due to natural cycles, and we are merely lucky enough to be living at a time when a couple of dozen of these cycles are peaking, or vallying. Yeah, that's the ticket.
 
2007-10-26 12:13:31 PM
pontechango: OK, this headline and summary misrepresent the argument presented in this article

Expect similar spins on it to echo around the blogopshere and AM radio for weeks at least.

It (the headline) also misrepresents the rational basis for mitigation decision making. One has to not only consider the probability of a negative consequence, but also the severity. As a gross oversimplification, take the example of Russian Roulette. The probability of shooting yourself is only 16.67%, but the severity of the consequence is tremendous. So even if someone offers you $1,000 on an 83.3% bet (fantastic odds by most standards), you're probably not likely to take it.

Similarly, even if the most severe consequences of increased emission are not easily determined to have a high probability, that is not a sufficient argument against the cost of mitigation, as the cost of being wrong is tremendous.
 
2007-10-26 12:14:56 PM
tbn0.google.com


Okay, maybe now I'll start recycling...
 
2007-10-26 12:18:17 PM
Jon Snow: It (the headline) also misrepresents the rational basis for mitigation decision making. One has to not only consider the probability of a negative consequence, but also the severity. As a gross oversimplification, take the example of Russian Roulette. The probability of shooting yourself is only 16.67%, but the severity of the consequence is tremendous. So even if someone offers you $1,000 on an 83.3% bet (fantastic odds by most standards), you're probably not likely to take it.

That's an excellent analogy. I'm going to have to pilfer it. :-)
 
2007-10-26 12:22:28 PM
Jon Snow: and continuing with that analogy w/respect to this study, it's kind of like somebody saying they can't remember whether they put two bullets in the chamber or one, therefore the exact probability of you getting shot is uncertain and, therefore, you should spin the barrel and take a shot.
 
2007-10-26 12:25:33 PM
JosephFinn: Another study shows that precise climate predictions are about as accurate as the precise predictions your local weatherman 's predictions of tomorrow's weather

So pretty damn good, eh? Meterologist next-day forecasts are generally considered in the 90% range for accuracy. It's longer thna three-five days where it starts to get wooly.


You just have to learn how to use black and white, all or nothing thinking.

Things are either 100% accurate, or they're completely inaccurate, you see. So since your local weatherman is sometimes wrong, all of his predictions are useless. Same thing with Wikipedia articles, or with scientific theories (which might change one day, or which are based on data, some part of which might turn out to be inaccurate).
 
2007-10-26 12:26:14 PM
of course saying that it is like "Russian Roulette" makes it seem like there is a chance that YOU WILL DIE as a result of climate changes.

which is very very unlikely.
 
2007-10-26 12:31:58 PM
Pro Zack: of course saying that it is like "Russian Roulette" makes it seem like there is a chance that YOU WILL DIE as a result of climate changes.

which is very very unlikely.


Old people. Chicago. Summer *and* winter. Coming and going.
 
2007-10-26 12:32:55 PM
LowbrowDeluxe:
Old people. Chicago. Summer *and* winter. Coming and going.


Except of course, I forget, the sick, weak, and old don't matter because they might have died anyway. Screw 'em. We're all healthy and young, nothing bad will ever happen to us.
 
2007-10-26 12:34:20 PM
LowbrowDeluxe

OH MY FARKING GOD!!!! Old people are dyeing? Everybody panic.
 
2007-10-26 12:35:17 PM
Sick people die, too. We're going to hell in a handbasket.
 
2007-10-26 12:38:31 PM
OH MY FARKING GOD!!!! Old people are dyeing? Everybody panic

/FTFM
 
2007-10-26 12:42:49 PM
Pro Zack: of course saying that it is like "Russian Roulette" makes it seem like there is a chance that YOU WILL DIE as a result of climate changes.

Why stop there? Saying that the climate is like a gun makes it seem like there is a chance that the earth will shoot a projectile into outer space. In other words, it's just an analogy for a highly hazardous outcome associated with a low probability. Sorry if you don't understand analogies.
 
2007-10-26 12:43:07 PM
chris20202:
Things are either 100% accurate, or they're completely inaccurate, you see. So since your local weatherman is sometimes wrong, all of his predictions are useless. Same thing with Wikipedia articles, or with scientific theories (which might change one day, or which are based on data, some part of which might turn out to be inaccurate).

Well said, my friend.
 
2007-10-26 12:45:59 PM
pontechango: highly hazardous outcome associated with a low probability

I am looking forward to your analysis of how global warming is highly hazardous.
 
2007-10-26 12:51:06 PM
Pro Zack: of course saying that it is like "Russian Roulette" makes it seem like there is a chance that YOU WILL DIE as a result of climate changes.

which is very very unlikely.


BTW, the major problem with climate change mitigation is that most people can not conceive of long-term risks. Are bodies are hard-wired to think in terms of short-term, fight or flight risks. It's an evolutionary adaptation and it blinkers our rationality in terms of larger, trans-generational decisions, especially for an era in which instant gratification is encouraged.
 
2007-10-26 12:54:33 PM
Pro Zack: I am looking forward to your analysis of how global warming is highly hazardous.

It's the consensus of the largest scientific body on the planet.
 
2007-10-26 01:05:00 PM
http://www.gtp89.dial.pipex.com/19.pdf

General conclusions include the following [19.3].

• Some observed key impacts have been at least partly attributed to anthropogenic climate change. Among these are increases in human mortality, loss of glaciers, and increases in the frequency and/or intensity of extreme events.

• Global mean temperature changes of up to 2°C above 1990-2000 levels (see Box 19.2) would exacerbate current key impacts, such as those listed above (high confidence), and trigger others, such as reduced food security in many lowlatitude nations (medium confidence). At the same time, some systems, such as global agricultural productivity, could benefit (low/medium confidence).

• Global mean temperature changes of 2 to 4°C above 1990-2000 levels would result in an increasing number of key impacts at all scales (high confidence), such as widespread loss of biodiversity, decreasing global agricultural productivity and commitment to widespread deglaciation of Greenland (high confidence) and West Antarctic (medium confidence) ice sheets.

• Global mean temperature changes greater than 4°C above 1990-2000 levels would lead to major increases in vulnerability (very high confidence), exceeding the adaptive capacity of many systems (very high confidence).

• Regions that are already at high risk from observed climate variability and climate change are more likely to be adversely affected in the near future by projected changes in climate and increases in the magnitude and/or frequency of already damaging extreme events.
 
2007-10-26 01:17:25 PM
Well, tomorrow's forecasts are extremely accurate. It is only morons who dwell on one missed forecast yet ignore the other 10 that were dead-on.
 
2007-10-26 01:47:36 PM
"It now appears that the estimates will never get much better. The reason lies with feedbacks in the climate system. For example, as the temperature increases, less snow will be present at the poles. Less snow means less sunlight reflected back into space, which means more warming."

It now appears that the estimates will never get much better. The reason lies with feedbacks in the climate system. For example, as the temperature increases, more water will evaporate into the sky. More cloud cover means more sunlight reflected back into space, which means less warming.
 
2007-10-26 01:52:36 PM
Can someone explain how throwing your hands in the air saying that we cannot come up with a repeatable experiment, and being able to state the results to within a statistical margin, part of the proving process of science. Isn't one of the tenants of proving scientific theory the ability to reproduce your work within a statistical error?

Until they can create some system to prove their hypothesis it is an unproven scientific theory and not fact. Or are we to take these theories on faith.
 
2007-10-26 01:57:41 PM
Jon Snow: pontechango: OK, this headline and summary misrepresent the argument presented in this article

Expect similar spins on it to echo around the blogopshere and AM radio for weeks at least.

It (the headline) also misrepresents the rational basis for mitigation decision making. One has to not only consider the probability of a negative consequence, but also the severity. As a gross oversimplification, take the example of Russian Roulette. The probability of shooting yourself is only 16.67%, but the severity of the consequence is tremendous. So even if someone offers you $1,000 on an 83.3% bet (fantastic odds by most standards), you're probably not likely to take it.

Similarly, even if the most severe consequences of increased emission are not easily determined to have a high probability, that is not a sufficient argument against the cost of mitigation, as the cost of being wrong is tremendous.



hmm... probability and magnitude... i seem to recognize those concepts...

oh right, it's the cornerstone of risk assessment in almost every aspect of the professional world.

very astute point.
 
2007-10-26 01:59:27 PM
Pro Zack: of course saying that it is like "Russian Roulette" makes it seem like there is a chance that YOU WILL DIE as a result of climate changes.

which is very very unlikely.



the victims of earth's previous planetary mass-extinctions would like to have a word with you
 
2007-10-26 02:01:06 PM
Tommy Moo: For example, as the temperature increases, more water will evaporate into the sky. More cloud cover means more sunlight reflected back into space, which means less warming.

Water vapor is also a greenhouse gas, so more water vapor means more warming. And clouds aren't as dependable for their albedo as ice sheets.
 
2007-10-26 02:04:23 PM
What we don't know could fill a book, but who would write it?
 
2007-10-26 02:11:12 PM
pontechango: Tommy Moo: For example, as the temperature increases, more water will evaporate into the sky. More cloud cover means more sunlight reflected back into space, which means less warming.

Water vapor is also a greenhouse gas, so more water vapor means more warming. And clouds aren't as dependable for their albedo as ice sheets.


While this is true, it is also true that the reason it doesn't snow very much in the anarctic is because it is too cold to support enough water vapor. It also doesn't snow that much in the high arctic during the coldest part of winter. I'm not willing to make a prediction, because I'm one who thinks the world's weather is mostly driven by ocean currents. I don't think we can predict what affect warming will have on snowfall - but I do believe the ice in the high elevations of Greenland is increasing due to increased snowfall.

The scenario I'm most curious about is if the conveyor belt shuts down (as it did in the last glaciation) (and as it partially did during the "little ice age" from 1500 to 1850) leads to very large snowfalls in certain areas. I personally believe that a permanent, very strong low pressure will set up over the Great Lakes and in the winter there will be more snow fall than can melt in the summer. The Great Lakes are there because that was the thickest part of the ice sheet, which was probably(?) caused by said permanent low pressure.

So, that said, global warming will either lead to a complete melting of the ice, and a drowning of islands and coastal areas; or it will lead to another ice age. Take your pick.
 
2007-10-26 02:15:20 PM
It's interesting to note that the conclusion that the study's authors reached was not that we do not have enough information to make a decision to begin mitigation, but rather that the inherent uncertainty linked to climate sensitivity means that further delay is impractical, and that we need to take action now.

Scientific American has a much more clearly written report on the study and has comments from its author, other scientists, and economists.
 
2007-10-26 02:20:09 PM
Jon Snow: It's interesting to note that the conclusion that the study's authors reached was not that we do not have enough information to make a decision to begin mitigation, but rather that the inherent uncertainty linked to climate sensitivity means that further delay is impractical, and that we need to take action now.

Umm.. that's what I said, but you said it better. :-)
 
2007-10-26 02:27:54 PM
dhudd: The scenario I'm most curious about is if the conveyor belt shuts down...

snip

...or it will lead to another ice age.


That almost assuredly would not happen this century, even in the most grim emissions scenarios. We've got some time to avoid the kind of melting necessary for something that drastic. And although it might not seem like it from what one reads on Fark, in the real world, it's pretty much a given that emissions reductions are inevitable.
 
2007-10-26 02:28:38 PM
The way I understand it, daily forecasts are made by looking at the current conditions, comparing them to similar conditions in the past, then checking those past occurances to see what they produced (e.g., 90% of the time they produced rain, etc.)

If that's correct, then it does seem a bit of a stretch to say we're heading toward [ice age/global warming] when we cannot compare the current conditions to anything that would lead us to such a conclusion.

Having said that, it seems to me that taking care of the planet by reducing the the poisons or other destructive elements would be something that every wants, no matter what the implied consequences are supposed to be. Even if we dispute the exact effects, I think it's a given that they can't be good.
 
2007-10-26 02:31:35 PM
pontechango-

Didn't mean to be redundant, but I was struck by the difference in clarity between the SciAm and New Scientist reports.

BTW- I also like the number of bullets addition to the analogy. I am going to have to work that into the analogy in the future.
 
2007-10-26 02:32:28 PM
Jon Snow: dhudd: The scenario I'm most curious about is if the conveyor belt shuts down...

snip

...or it will lead to another ice age.

That almost assuredly would not happen this century, even in the most grim emissions scenarios. We've got some time to avoid the kind of melting necessary for something that drastic. And although it might not seem like it from what one reads on Fark, in the real world, it's pretty much a given that emissions reductions are inevitable.


Frankly, I disagree about the "we have time". So much methane is going to be released from the melting permafrost that it's a foregone conclusion. I just don't want to predict what's going to happen next.
 
2007-10-26 02:32:56 PM
buenohead: Having said that, it seems to me that taking care of the planet by reducing the the poisons or other destructive elements would be something that every wants, no matter what the implied consequences are supposed to be. Even if we dispute the exact effects, I think it's a given that they can't be good.

You'd think that wouldn't you? But when doing something about it means fewer profits or any sort of lifestyle sacrifice, turns out you'd be thinking wrong.
 
2007-10-26 02:39:21 PM
Another global warming denier that needs to be educated on the error of their ways.
 
2007-10-26 02:42:11 PM
Saiga410:

Can someone explain how throwing your hands in the air saying that we cannot come up with a repeatable experiment, and being able to state the results to within a statistical margin, part of the proving process of science. Isn't one of the tenants of proving scientific theory the ability to reproduce your work within a statistical error?

Until they can create some system to prove their hypothesis it is an unproven scientific theory and not fact. Or are we to take these theories on faith.


A doctor cannot *prove* that you will die young if you switch to an all-cheeseburger and soda diet.

He can show the effects of salt, fat and coke on countless lab animals of all types under different conditions.

He can predict that you will get fat, that your blood pressure will go through the roof, and that you will become diabetic.

These things might happen over time, but he has not yet *proven* that you're going to croak early. He cannot point to a calendar and say "this is when you will be at 400 pounds, and over here is where your blood pressure will be at such and such level. The heart attack happens the following tuesday."

You might be lucky... There might be genetic factors he doesn't know about, maybe your mental state is unusually stress-free, who knows.

But the doctor is not "just taking it on faith" that it will cause health problems, and he's not flying blind about their progression, and he can give you answers within a statistical margin.

Same goes for an engineer. He can test materiels, run simulations, stuff like that, but he can't *prove* whether a dam will fail or not until it's built.

And so with climate change. We can pin it down to within certain ranges. These ranges get stated in the papers. If you look at the IPCC report they tell you the confidence levels on each prediciton.
 
2007-10-26 02:43:42 PM
Jon Snow: Didn't mean to be redundant, but I was struck by the difference in clarity between the SciAm and New Scientist reports.

Agreed. I never put much stock in New Scientist. The Nature Podcast (new window) is where it's at.
 
2007-10-26 02:46:44 PM
dhudd: Frankly, I disagree about the "we have time". So much methane is going to be released from the melting permafrost that it's a foregone conclusion. I just don't want to predict what's going to happen next.

There is nothing to indicate that we have already crossed some sort of threshold guaranteeing the collapse of Greenland's ice sheet. Concluding that it's too late is honestly not any more help than concluding that nothing is happening. We have the technology, the time, and the money to actually keep this from becoming a complete catastrophe. There's no reason to throw in the towel.
 
2007-10-26 02:48:52 PM
pontechango: Agreed. I never put much stock in New Scientist. The Nature Podcast (new window) is where it's at.

I've seen the site but never actually listened to one. It seems like there's never enough time...
 
2007-10-26 02:57:49 PM
Interesting.

Also interesting is the latest to come from the scientific community at the UN.

Seeing as we are just days away from dogs and cats living together in harmony, what pray tell is the immediate solution? How should it be implemented and how enforced?
 
2007-10-26 03:01:09 PM
You know, the weatherman is right about 95% of the time. We just take that for granted and notice when they're hilariously off the mark.
 
2007-10-26 03:03:44 PM
Tommy Moo: More cloud cover means more sunlight reflected back into space, which means less warming.

You know, Venus has a hell of a lot of cloud cover. That must be why its surface is so cool.

/who's up for a refreshing dip in a lake of molten lead?
 
2007-10-26 03:15:32 PM
pontechango: Pro Zack: I am looking forward to your analysis of how global warming is highly hazardous.

It's the consensus of the largest scientific body on the planet.


...and that's the part where I jump off.

I can't take something too seriously when the scientists say "well, we can't prove it, but we all pretty much agree, so let's just call it good enough."

Science != consensus.

Yep, you guys might be right. How about we engage in some standard of proof and properly constructed theories and not guesswork?

Caloric fluid, anyone?
 
2007-10-26 03:17:20 PM
Jon Snow: dhudd: Frankly, I disagree about the "we have time". So much methane is going to be released from the melting permafrost that it's a foregone conclusion. I just don't want to predict what's going to happen next.

There is nothing to indicate that we have already crossed some sort of threshold guaranteeing the collapse of Greenland's ice sheet. Concluding that it's too late is honestly not any more help than concluding that nothing is happening. We have the technology, the time, and the money to actually keep this from becoming a complete catastrophe. There's no reason to throw in the towel.


You are aware of what is going on in Siberia vis-avis the release of methane?
 
2007-10-26 03:37:59 PM
The Fark headline is, as usual, totally wrong.

The study doesn't show that you can't estimate climate sensitivity. They try to show that you can't rule out very high sensitivities.

And even that is predicated on some strong assumptions. Specifically, they assume that there is normally distributed uncertainty in determining the feedback strength, and show this implies (through feedback-sensitivity nonlinearity) a long tail to the climate sensitivity distribution.

But this begs the question! It just shifts the argument from "does climate sensitivity have a long tail" to "is feedback strength normally distributed"?

If you could actually measure feedback strength, then you could argue that your observation error is normal: most observation errors are. But you can't measure feedback strength! What you measure are things like temperature, ocean heat uptake, and other physical observables. Those are all related nonlinearly to the feedback strength. Then, following their own argument (normal errors in feedback mean non-normal uncertainty in sensitivity), you can argue that normal errors in temperature observations should imply non-normal uncertainty in feedback strength: invalidating their assumption. Their entire argument hinges on that very strong assumption!

It has already been shown that adding multiple observational constraints has the power to eliminate a lot of the "long tail" (i.e. help to rule out very high sensitivities); James Annan in particular has argued this for a long time, and there are several papers where adding extra constraints, such as ocean heat uptake, cuts off a lot of the tail. (Tomassini et. al this year in J. Climate is the most recent I've seen.)

Since it is directly demonstrable that observational constraints can seriously reduce the probability of high sensitivities, their whole argument is suspect. While there is still a "long tail" in climate sensitivity, you can still get rid of a lot of it - and that is what is policy-relevant.
 
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