Friday, August 18, 2006

Glacial Cycles and Global Warming

One of the chief statements I have seen that has been coming from disbelievers in Global Warming comes from the fact that science is ever learning. It is still figuring out how things work with respect to climate and over time has made significant progress. However, as things are learned, they are often brought out and trumpeted as the new and all important fact. This is a consequence of the funding models for science these days.

During the 1970s and up through 1980, climatologists discovered one of the elements that enduce effects on the climate. When something has an effect, it's called, in the climate world, 'forcing'. In this case, it was the orbital forcing and the cycles that come about from the fact that the Earth's orbit changes a small amount, in relative terms, over time in a cyclical manner. These are called the Milankovitch Cycles. During the 1970s, this was developed into its current form, more or less.

As a theory, it's not without it's own issues, to be sure. Check the wikipedia entry for more. However, it does seem to have an impact on the climate of the world and does seem to correspond to the observed glacial cycles of the Pleistocene (the last geological epoch) which is the easiest to document due to its recent geological time frame.

However, during the 1970s, recieved press. People heard of it. Scientists trumpeted the coming of the ice. Or at least the popular science press did and it made a definite impression. Now fast forward. The 1990s and late 1980s people began to discover that people can effect the atmosphere pretty significantly. One of the most famous was the ozone hole caused by CFCs over Antarctica. At about the same time, we discovered that the CO2 that we have been pumping into the atmosphere was having a nontrivial effect on the climate and would have a lot more to come. The science then was pretty raw, very new, and rather fanastic at the time. The popular press took up the call and blew the horn.

Now fast forward to the present day.

The same people that heard about the coming ice age in 6k years via the Milankovitch Cycles are now scoffing at the current Global Warming. They say, "We've heard this all before but it was global cooling, not warming." Pravda! Yet, there was a good reason and this argument as put forth is inane and disingenus at best.

Science makes forward progress. As we learn, we find things are more important than we originally assumed. Theories grow, change, and are discarded. The fact that they found the 'key' to the glacial cycles at an earlier time does not preclude the fact that we, as a species, are changing the carbon cycle to such an extent that it has having an impact on the global climate. We learned something new. We found a new layer on top of the previously discovered one.

We have since tested that theory. It appears to be correct in theory, the computational models, and in the field. It's effects outstrip that of the Milankovitch Cycle. It's effects are longer lasting than a single Milankovitch Cycle, or even two for that matter. It appears that it will take 50,000 years or more, if we were to stop cold turkey now, for the carbon cycle to have returned to its 'previous' state. That's not going to happen, frankly, because we're not stopping cold turkey any time soon.

It's not to say that this is the only effect going on. It appears that there is another layer to the climatological onion: global dimming and it has its own effects as well. They're nontrivial. I am not sure if there are any atmospheric models that take it into account. I speak from ignorance here. They very well may. However, when it comes into play, if it has not already, I am sure that the scoff-sciences will mock this one too. Even though there's a lot of data here that support it (Evaporation rates and the unique circumstances that grounded all the planes on 9/11 that allowed for a measurement of the differences in temperature and other data during those days when very little flew).

Just remember, like children, we're still learning. Even when we think we have things figured out, we still have more of that climate onion to peel. That doesn't mean that the the previous discoveries were incorrect, just incomplete. That doesn't mean that the current theories and models are wrong, just that there may be more to it. It also means that as our knowledge gets more complete, the understanding and predictive power of the information will get better. It may well be that we have crossed a observational threshold since we are able to model backwards since the 1600s to the present accurately that we can comfortably say we're close to an accurate enough theory that we can make relatively good predictions about the future.

So, as a favour, please, don't use such stupid arguments anymore, it only demeans you.


No comments: