07-16-2009, 04:49 PM
Hi,
If the decrease in the density of the waters of the North Atlantic is sufficiently slow, then the Atlantic currents will not be greatly effected, and (ignoring other factors) heating will continue, possibly to the desert planet stage. Whether this scenario occurs depends on many factors and relationships, such as how fast the ice will melt, how fast the layers of different density and temperature will mix, etc. etc.
If the decrease in the density of the North Atlantic is sufficiently fast, then the Atlantic currents *may* stop (again, a complex problem in itself). If these currents stop, the higher latitudes will become cold. This will reduce the absolute water content of the air at those latitudes. If that reduction is sufficient to offset the increased CO2, then a positive feedback cooling cycle can start which will lead to a snow ball planet.
The point is that a cause (say CO2) has many different effects. Some of these effects form feedback loops, both positive and negative. So the effects then become causes in their own right.
Now, one might say, "If increased CO2 levels lead to either a desert planet or a snowball, why does it matter which? Either way we need to control it." But the point that's missed there is that it can lead to either extreme, or any point in between. If, as some climatologists think, earth's natural progression should be taking us into the next ice age, then artificial global warming might be a good thing. That may be, probably is, highly unlikely. But on the basis of what we've got and what we know, it cannot be ignored.
--Pete
Quote:Ignorant question: since all we want to know is how an increase in CO2 (without any other major global changes - like earthquakes or what not) affects global temperatures why wouldn't modeling what happened since the industrial revolution be sufficient? Has that ever happened before?Leaving out earthquakes, volcanic eruptions, meteor strikes, global war, etc., is fine. These things are not directly related although they can have their effects. But you can't leave out things like the melting of the polar icecaps, the loss of snow cover, the melting of the tundra, etc., because these are related effects. As a simple example (partially repeated from a previous post): CO2 warms the earth; the warmth causes the polar ice caps to melt; the melt is mostly fresh water which decreases the density of the North Atlantic; at this point we have a bifurcation in the model.
If the decrease in the density of the waters of the North Atlantic is sufficiently slow, then the Atlantic currents will not be greatly effected, and (ignoring other factors) heating will continue, possibly to the desert planet stage. Whether this scenario occurs depends on many factors and relationships, such as how fast the ice will melt, how fast the layers of different density and temperature will mix, etc. etc.
If the decrease in the density of the North Atlantic is sufficiently fast, then the Atlantic currents *may* stop (again, a complex problem in itself). If these currents stop, the higher latitudes will become cold. This will reduce the absolute water content of the air at those latitudes. If that reduction is sufficient to offset the increased CO2, then a positive feedback cooling cycle can start which will lead to a snow ball planet.
The point is that a cause (say CO2) has many different effects. Some of these effects form feedback loops, both positive and negative. So the effects then become causes in their own right.
Now, one might say, "If increased CO2 levels lead to either a desert planet or a snowball, why does it matter which? Either way we need to control it." But the point that's missed there is that it can lead to either extreme, or any point in between. If, as some climatologists think, earth's natural progression should be taking us into the next ice age, then artificial global warming might be a good thing. That may be, probably is, highly unlikely. But on the basis of what we've got and what we know, it cannot be ignored.
--Pete
How big was the aquarium in Noah's ark?