29 June 2005

Not my axe to grind, but...


As I am sure everyone can agree, there are some ideas out there that just seem crazy. One such idea is this one, which proposes that we organize an array of orbital bodies around our home planet to help combat global warming. Now, as an semi-avid amateur astronomer, this idea fills me with horror, as I would not be able to enjoy the night sky with this big structure brightening the night from horizon to horizon. However, there is a bigger issue here, that I am going to attempt to tackle: Global Warming.


Now, I will say straight away that I am not an environmental scientist, nor a specialist of any kind in this field. However, in my undergrad days, during, I believe, this class, taught by the best prof. I have ever encountered (see left), I was given a different view of the issue. One which I seldom see mentioned in the media, or by "green" groups, but I do find in academic settings. So, I will do my best to reproduce, below, the lesson my favorite prof imparted, with help from data I culled from the web.

-First, we must ask ourselves if global warming is actually happenning. To do this, let us not simply look at a small data set (geologically speaking), but at as broad an overview as possible.



This graph, which I grabbed from the University of Leeds, does indeed show that during recent, "modern" history, there has indeed been an upward trend in average global temperature. In fact, the science academies of the G8 nations issued a joint statement, including the National Academy of Sciences, via the Royal Society of the UK, stressing that the "scientific understanding of climate change is now sufficiently clear to justify nations taking prompt action," including, "Acknowledg[ing] that the threat of climate change is clear and increasing."

Ok, so if there is an upward trend in temperatures, can a reason be discerned? Greenhouse gases seem to be a likely suspect. Ozone depletion also looks like a possible cause. In general, though, these causes supposedly all add up to the warming process known as the greenhouse effect. This effect has many in the scientific community worried, enough so for some very dire warnings regarding the results of this warning to be issued, and also some creative solutions, such as the one I mentioned above.

Oh, but wait, I said we should look at as broad a data set as possible, didn't I? Well, the the Intergovernmental Panel on Climate Change (IPCC) report that the science academies used as their primary reference uses data from as far back as 1861, and makes statements regarding global climate ranging as far back as 1000 years ago. Certainly that is a good data set? Let us take a longer view of Earth's temperature history, to be certain:
Wow, that first graph shows that before the mid-to-late 1800's, there was a global event going on known as the Little Ice Age. That's right, we are still just coming out of that. Prior to that, it looks as if there was another temperature shift known as the Medieval Warm Period, and it sure looks like it was just as warm as, if not warmer, than where we are going. Looking even farther back, as the second graph shows, there was another cool era, preceeded by another warm period known as the Holocene Maximum - again, quite a warm spell, during the period of about 7,000 to 5,000 years ago.

Those are quite some variations. Well before the industrial age, too. I wonder what could have caused all those climatic shifts? Perhaps if we look farther back, we will see a pattern, and that might give us a clue:


Wow, stretching the timeline out like that makes it appear that there is indeed a rough pattern. Since nothing in the nature seems to fit a perfectly cyclic pattern, let's assume this does conform to a pattern. If this is so, then there should be an identifiable cause.

Perhaps, just as expanding our scope of observation for time helped us see a possible pattern, expanding our view of the system involved will help us see a cause. After all, Earth is part of a much larger system:
In this system, Earth behaves in predictable, cyclic ways - hence why I first heard about this in a physics class. For a quick summary of how Earth's orbital behavior might affect global climate, look here. But, to give my own summary, Earth's varying inclination towards the sun, its orbital eccentricity, and the movement of its rotational axis - known as precession, all play into how the larger solar system affects Earth's climatic system. Integrating these various effects into a predictable cycle gives something known as Milankovitch cycles. Wow, these predicted cycles fit pretty decently into the known, larger data set. But it doesn't account for everything, including the current warming trend, which, in all fairness, is still such a relatively small event that it would not really show up on such a long-scale cycle.

So are there any "larger system" explinations that might also account for the current warming trend? Well, first, let us determine where our heat is coming from. Ok, that was a little obvious. Does our primary heat source have any known variations? Why yes, it does, and they can give us some additional insight as well:
(Thanks again, NASA)

The number of sunspots produced by the sun give us a good measure of its activity, which directly relates to its thermal output. So we can use the sunspot numbers to track the approximate thermal output of our sun. It appears to track with our known data, too! The dip in sunspot sightings, known as the Maunder Minimum, correlates quite well with that Little Ice Age we discussed before! And since sunspots follow a fairly predictable cycle, and we currently are on an upswing, both per theory and observation, that might account for our current warming trend.

So, we have established that a longer view of Earth's timeline and a larger sytemic view give us some significant, and possibly suprising, insights. So, let's look at where this view points us. One study, J Imbrie, J Z Imbrie (1980). "Modeling the Climatic Response to Orbital Variations". Science 207 (1980/02/29), which takes into account these views, states, "Ignoring anthropogenic and other possible sources of variation acting at frequencies higher than one cycle per 19,000 years, this model predicts that the long-term cooling trend which began some 6,000 years ago will continue for the next 23,000 years."

What?!? So we are actually, potentially headed into a cooling period, and right now are only in a "local" warm period?! Ack. Perhaps this global warming thing is a -GOOD- idea.

In all seriousness, I am not suggesting that CFCs, ozone depletion, burning dirty coal, and the like are a good thing. Pollution does damage, hurts crops, hurts people. The lack of ozone has been linked to cancer (ask folks in South America). However, tying these to global warming to try and prove how bad they are just seems silly. There are plenty of VALID reasons to worry about these things without playing chicken little and crying, "The sky is falling, the sk... errr, the sea is rising, the sea is rising!" Earth, and its climate, is not a steady state system. Temperatures change, climates shift. What we should be worrying about is how to adapt, not how to maintain the climate how it is. We can't. It is a system filled with amazingly huge energies, one which we might cause a slight perturbation in now and then, but one which we will very likely not be able to affect to any great extent.

So, I would caution anyone who take the global warming arguement seriously. It does not consider the entire realm of data or the whole system involved. It is, therefore, in my very humble opinion, BAD SCIENCE. Stay skeptical, and remember, nature is almost always cyclical.
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4 Comments:

At 6/30/2005, Blogger WillyShake said...

This is an OUTSTANDING posting--you should consider writing it up in (short) article form and sending it over to Tech Central Station!

 
At 6/30/2005, Blogger PigBoatSailor said...

*blush*

Aww, gee....

I will admit, it took some degree of self-restraint not to just title it, "Global Warming = Big Myth"

 
At 7/01/2005, Blogger Alex Nunez said...

Ouch.

PBS, my brain hurts now.

 
At 7/02/2005, Blogger Xopher said...

Excellent post. I wonder about accuracy of the data, seems like a small spread. Maybe you can cover that in your full write up. :)

Ozone and health effects of pollution are the real reason, just like you said. More Nukes!

 

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