appleman2006 wrote:And yet the guy portraying your side in Peter's example of a debate clearly admitted that the models do not hold up very well. Did he not?
I generally agree with Kerry (GuestE),
who said this:
GuestE: Let me just preface my answer here to your important question by saying that a lot of what we know about the climate system was predicted long before there was such a thing as a climate model. It's a mistake to think that everything we knew about climate or predictions about climate are based on complicated models. Having said that, we have built over the years a hierarchy of increasingly complex models that really are some of the most complicated pieces of software that the human race has ever constructed. They have their origins in models that were built for a much more pedestrian but important purpose, which is weather forecasting. And they are very complex. In the case of weather forecasting, arguably you can test them twice a day and see how well they are doing. With climate, it's much more difficult to test them because we don't have that many climate states. But we do experiments that are much along the lines of what you had just described as done with economic models. We try to hold certain variables constant, like sunlight. And vary another external factor, like carbon dioxide, to see how the system responds.
Christy (GuestC) emphasized that we cannot exactly calculate these things, though we do know the formulas (unlike economics):
GuestC: Uh, no, it isn't the same. Because there is a huge difference between climate modeling and economic modeling. We know the equations. You guys don't. Okay? And we actually know the equations we are trying to solve. And the problems come with actually trying to solve them. And arguably our computers aren't nearly powerful enough to really solve them exactly; and they won't be for generations, unless there is some unbelievable breakthrough in computation.
Kerry (GuestE) replied that may not be able to calculate these things exactly, but we don't need to either, because the predictions are robust even if the exact numbers change some. And you don't need really complicated models for much of this, simple models work just fine.
GuestE: Let me just preface my answer here to your important question by saying that a lot of what we know about the climate system was predicted long before there was such a thing as a climate model. It's a mistake to think that everything we knew about climate or predictions about climate are based on complicated models. Having said that, we have built over the years a hierarchy of increasingly complex models that really are some of the most complicated pieces of software that the human race has ever constructed. They have their origins in models that were built for a much more pedestrian but important purpose, which is weather forecasting. And they are very complex. In the case of weather forecasting, arguably you can test them twice a day and see how well they are doing. With climate, it's much more difficult to test them because we don't have that many climate states. But we do experiments that are much along the lines of what you had just described as done with economic models. We try to hold certain variables constant, like sunlight. And vary another external factor, like carbon dioxide, to see how the system responds.
Is it biblical? Is it Christlike? Is it loving? Is it true? How can I find out?