What kinds of possible evidence would you expect to see if such positive feedbacks can happen?
I’m not sure what you mean by “can happen,” since in some sense lots of things “can happen.”
Anyway, it’s not a full answer to your question, but the gold standard for substantiating the water vapor feedback hypothesis would be if the proponents of that hypothesis made specific interesting and accurate predictions about future events.
To paraphrase Eliezer, ceteris paribus and without anything unknown at work, water vapor is a greenhouse gas and ought to make the Earth hotter. Also, ceteris paribus and without anything unknown at work, a hotter Earth ought to lead to more water vapor in the air.
I disagree, and perhaps an anlogy would help: All things being equal, cooler weather can be expected to lead to more snow cover. And all things being equal, more snow cover can be expected to result in cooler surface temperatures because of effects on the Earth’s albedo. So should we worry that the next big volcano will trigger an ice age?
The answer is “no,” and I think the mistake here is two-fold. First, rough reasoning gets exponentially rougher as you travel along a chain of deduction. Second, we can’t ignore the fact that the Earth’s climate is a complicated system which has been around for a long time. The normal assumption should be that if you push on such a system, then it will probably push back at you.
the gold standard for substantiating the water vapor feedback hypothesis would be if the proponents of that hypothesis made specific interesting and accurate predictions about future events.
No, that is evidence of authority. The gold standard would be if the assumptions that led to the hypothesis also led to specific interesting and accurate predictions about future events (and don’t lead to inaccurate predictions).
But when will it push back at you? Before or after it has triggered a mass extinction event?
There is evidence that there have been multiple mass extinction events in the planet’s history, some of which may have been caused by the earth getting too hot or too cold.
Could you give me an example or two of such mass extinction events which may have been caused by temperature changes? I would like to think about your point in context.
A system can have a balance between positive and negative feeback. If it has a mix of both, there’s amplification, not necessarily a runaway. (The balance between solar input and radiation to space, among other things provides negative feedback)
Moreover, it isn’t even just a multiplication problem. There are different styles of feedback—proportional, integral, differential—and those latter two can come with different time scales
It’s obvious that pushing the same direction for a hundred years can be much bigger a deal than pushing a hundred times as hard in the same direction for a day, but it’s also true of a hundred-times-as-strong push lasting for, say, two years. Or, depending on the different feedbacks, the hundred times as hard for a day could have a bigger effect.
What kinds of possible evidence would you expect to see if such positive feedbacks can happen?
I’m not sure what you mean by “can happen,” since in some sense lots of things “can happen.”
Sorry for the ambiguity. I should have reflected your wording more closely and written “What kinds of possible evidence would you expect to see if the climate operates by positive feedback in this way?” Part of the purpose of the question was to determine what you meant when you chose that wording.
Anyway, it’s not a full answer to your question, but the gold standard for substantiating the water vapor feedback hypothesis would be if the proponents of that hypothesis made specific interesting and accurate predictions about future events.
Since the effects are alleged to take place over decades, asking to see this evidence now is asking for impossible evidence.
I disagree, and perhaps an anlogy would help: All things being equal, cooler weather can be expected to lead to more snow cover. And all things being equal, more snow cover can be expected to result in cooler surface temperatures because of effects on the Earth’s albedo. So should we worry that the next big volcano will trigger an ice age?
A priori, yes we should. However, we would be justified in decreasing our concern if either (1) additional theoretical consideration show that, in fact, according to our best theory, that loop probably wouldn’t occur, or (2) despite our best theory, we’ve observed many big volcanoes erupt without setting off such loops.
Let us suppose that (2) is the case. Then this would decrease our confidence in our best climatological theory. However, if that same theory asserts that X will probably cause Y, where X is not very similar to something that we’ve observed in the past (so, not a big volcano eruption), then our best bet is still that Y will follow X, even though our theory blew it on the consequences of the volcano eruption. Our confidence in Y will go down, but it will exceed our confidence in ~Y. (Otherwise, the theory wouldn’t be our “best”.)
(To the best of my knowledge, our theories don’t mispredict the consequences of volcanoes, though, for all I know, that could be only because volcanoes were part of the input data used in the theories’ construction.)
The normal assumption should be that if you push on such a system, then it will probably push back at you.
This sounds like you want to construct a climate theory by taking an a priori first-principles theory and adding an ad hoc “push back” mechanism, according to which the current equilibrium is assumed to be more stable than the first principles would justify. It’s fine to believe in such a mechanism, even if you can’t justify it from first principles, provided that you have direct empirical evidence for it. In which case, great, add that evidence to the pile of all the other evidence that we use to justify beliefs about the climate, and let’s see how it all adds up.
Since the effects are alleged to take place over decades, asking to see this evidence now is asking for impossible evidence.
I’m not sure what you mean by “decades,” since the warmists have had well over 20 years now. Anyway, the warming which took place during the 1990s was alleged to have been the result of CO2 emissions, agreed? And do you agree that some of these computer climate simulations have been used to make shorter-term predictions?
A priori, yes we should.
Well, do you agree that there many different possible feedback loops one could postulate?
It’s fine to believe in such a mechanism, even if you can’t justify it from first principles, provided that you have direct empirical evidence for it.
I’m not sure whether you would classify it as a first principle or as empirical evidence . . . it’s just common sense.
I’m not sure what you mean by “can happen,” since in some sense lots of things “can happen.”
Anyway, it’s not a full answer to your question, but the gold standard for substantiating the water vapor feedback hypothesis would be if the proponents of that hypothesis made specific interesting and accurate predictions about future events.
I disagree, and perhaps an anlogy would help: All things being equal, cooler weather can be expected to lead to more snow cover. And all things being equal, more snow cover can be expected to result in cooler surface temperatures because of effects on the Earth’s albedo. So should we worry that the next big volcano will trigger an ice age?
The answer is “no,” and I think the mistake here is two-fold. First, rough reasoning gets exponentially rougher as you travel along a chain of deduction. Second, we can’t ignore the fact that the Earth’s climate is a complicated system which has been around for a long time. The normal assumption should be that if you push on such a system, then it will probably push back at you.
No, that is evidence of authority. The gold standard would be if the assumptions that led to the hypothesis also led to specific interesting and accurate predictions about future events (and don’t lead to inaccurate predictions).
I agree . . . as a practical matter there might not be much difference, but I agree.
But when will it push back at you? Before or after it has triggered a mass extinction event?
There is evidence that there have been multiple mass extinction events in the planet’s history, some of which may have been caused by the earth getting too hot or too cold.
Could you give me an example or two of such mass extinction events which may have been caused by temperature changes? I would like to think about your point in context.
A system can have a balance between positive and negative feeback. If it has a mix of both, there’s amplification, not necessarily a runaway. (The balance between solar input and radiation to space, among other things provides negative feedback)
Moreover, it isn’t even just a multiplication problem. There are different styles of feedback—proportional, integral, differential—and those latter two can come with different time scales
It’s obvious that pushing the same direction for a hundred years can be much bigger a deal than pushing a hundred times as hard in the same direction for a day, but it’s also true of a hundred-times-as-strong push lasting for, say, two years. Or, depending on the different feedbacks, the hundred times as hard for a day could have a bigger effect.
And all of that is without going nonlinear!
I’m not sure of that. If negative feedback dominates and overwhelms any positive feedback, then how would you get amplification?
Anyway, the burden is on the proponents of CAGW to demonstrate amplification. So far they have not done so.
Sorry for the ambiguity. I should have reflected your wording more closely and written “What kinds of possible evidence would you expect to see if the climate operates by positive feedback in this way?” Part of the purpose of the question was to determine what you meant when you chose that wording.
Since the effects are alleged to take place over decades, asking to see this evidence now is asking for impossible evidence.
A priori, yes we should. However, we would be justified in decreasing our concern if either (1) additional theoretical consideration show that, in fact, according to our best theory, that loop probably wouldn’t occur, or (2) despite our best theory, we’ve observed many big volcanoes erupt without setting off such loops.
Let us suppose that (2) is the case. Then this would decrease our confidence in our best climatological theory. However, if that same theory asserts that X will probably cause Y, where X is not very similar to something that we’ve observed in the past (so, not a big volcano eruption), then our best bet is still that Y will follow X, even though our theory blew it on the consequences of the volcano eruption. Our confidence in Y will go down, but it will exceed our confidence in ~Y. (Otherwise, the theory wouldn’t be our “best”.)
(To the best of my knowledge, our theories don’t mispredict the consequences of volcanoes, though, for all I know, that could be only because volcanoes were part of the input data used in the theories’ construction.)
This sounds like you want to construct a climate theory by taking an a priori first-principles theory and adding an ad hoc “push back” mechanism, according to which the current equilibrium is assumed to be more stable than the first principles would justify. It’s fine to believe in such a mechanism, even if you can’t justify it from first principles, provided that you have direct empirical evidence for it. In which case, great, add that evidence to the pile of all the other evidence that we use to justify beliefs about the climate, and let’s see how it all adds up.
I’m not sure what you mean by “decades,” since the warmists have had well over 20 years now. Anyway, the warming which took place during the 1990s was alleged to have been the result of CO2 emissions, agreed? And do you agree that some of these computer climate simulations have been used to make shorter-term predictions?
Well, do you agree that there many different possible feedback loops one could postulate?
I’m not sure whether you would classify it as a first principle or as empirical evidence . . . it’s just common sense.