Projects

My project folder has gotten unwieldy, so some things will show up here from there. The project folder (ok, it's now a shelf or two of bookcase) started when I realized that I had far more ideas than time to complete them. So I started making notes on the ideas so that at least I wouldn't forget what they were. But I'd also clear the brain a little to have room for new ideas. Some of those ideas have been published in the scientific literature, and some have sat quietly for upwards of 20 years.

A different sort of 'project' that will show up is where I'll suggest that you try something, or challenge you to answer something. In the former case, I probably know the answer and give some fair pointers to how to finish it. In the latter, I may not have the answer either; but it is a good question to have one for. Maybe some would be publishable in the scientific literature.

Probably a number of these will lend themselves to science fair projects.

Where I mention a project in a science note (like, say, the simplest meaningful climate model note) it may well also be that I don't expect you to take my word for things. If I'm talking science, you can do things yourself and come up with the same answer. I think it's a good thing to take the time and wrestle some with the guts of a problem. You'll understand a lot more that way (certainly I do). Plus, maybe I made a mistake and you can be the one to point it out. (In science this is normal and welcome. But you do have to provide more than 'ha ha, you're sooo wrong'.)

Climate is always changing

The subject line is a comment that surface surprisingly often in the literature of folks who want to deny that climate is changing, or if it isn't, that any of it is due to human activity, or if it is, then it will be good for us. Whatever. The science of interest here is the notion of climate change, how fast, how much, how often, and the like. The human side of concern ... we'll get to a bit of that as well.

As we look through the period where we have thermometers (the last 100 or so years) recording temperatures, we see that there are indeed changes from year to year (though a year is too short really to call climate) and decade to decade (a better period to average over). But this includes the period of significant human activity (the now 6+ billion of us), so doesn't necessarily tell us a lot about what the climate does without human effects.

For longer range, say the last 600-2000 years, we have climate proxies that tell us about climate without being thermometers. Tree rings and ice cores are two such sources of proxies. When we look here, we see that climate does change decade to decade, century to century, and even millennium to millenium. The changes are small, tenths of a degree for the global average (and the longer a period you average over, the smaller the changes). But they're observable and present.

Even longer term, we still have ice cores (to 800,000 years ago), and then also start looking at marine sediments (to about 100,000,000 years ago). We see here that climate still changes, even on 10,000 to 10,000,000 year time scales. A very large change, 5 C or so global average, is associated with the northern hemisphere ice age cycle. About as much is associated with the start of the Antarctic ice cap about 35 million years ago.

The exact causes for the changes are a subject of study with some good answers and some not as confident. They include carbon dioxide (greenhouse gas) changes, orbital variations (the earth's orbit isn't exactly constant), continental drift, and land surface changes.

So what do we need to consider as humans with human interests regarding climate? As scientists, we want to understand everything, through all of time. But as citizens thinking about policy, we can look at a few things. One thing is, although there have been large changes to climate before, humans weren't around for it, certainly not 6+ billion of us, many living in large cities near the ocean. Another is, these large climate changes were also associated with large extinctions. We might not want to cause climate change sufficient to drive a large extinction. During the glacial to interglacial warming 10-18,000 years ago, global human population was likely only a few million, and were largely nomadic. So when climate got bad in one area, they simply moved (or died). Today, with 6+ billion people occupying the earth in stationary cities, it'd be difficult to move out of the way if climate got bad where you were.

Perhaps the strongest indicator of our time scale of concern is human life. If change were to be small over 70 years, we might not be concerned as little would be different between our birth and death. More quickly, we might want to ensure that there was reasonable stability between the time our kids were born and the time they reached adulthood, 20ish years. Given the two, 'a few decades' becomes our time range. Cities also point us towards the few decade time scale -- it is on this scale that urban infrastructures are built and rebuilt. If changes are slow enough that 'all' we have to do it rebuild the city further inland over the next 50 years, for instance, then relatively simple practices could get us there (but this would require some consideration on how to carry it out, as people who live now in the area marked not to be rebuilt might object!).

So, while I'm very interested as a scientist in, for instance, the 100,000 year cycles of the ice ages (my first scientific paper was on it), it's just too slow to be a concern to me as a citizen. As a citizen, I'd as soon that scientists did understand the 100,000 year cycle -- the more that is understood, the more likely that good estimates can be made of the futures. But the estimates that matter are those for the next few decades to maybe a century or two.

Climate confusion

Part 3 with Dave's comments

Thirdly you have global warming, and then you have "Man Made global warming" and people start getting defensive if all of a sudden you start blaming them for the impeding end of the world unless "we all change the way we live and our lives now and this is how you do it".
Fourthly you see it in mainstream media now all too much: Everything and anything that is out of the ordinary now has some relationship to global warming, no matter how ridiculous.
So here I sit with 27,000 scientists saying one thing and another 27,000 scoffing at the huliboo. Who do I believe? I have seen calm rational debate from both sides. We've had global warming before. It would seem hard to argue that man hasn't had some effect but to what degree?

Agreed about the media thing. It's one of the things which irritates the scientists who are trying to communicate accurate, careful, correct information. People hear wild claims in the media, and then when we discuss what we really know and how well, we don't get believed (since we're not as extreme as the media reports, it's no story). ('we' by the way doesn't exactly include me. I haven't talked to the media for a long time, and it wasn't about this. Still, I do know folks who get quoted.)

One thing for you to do, with the 27,000 on either side of you, is to start looking at what they're scientists of. It turns out that the 27k saying that climate is changing and part of the reason is human activity are climate scientists, while the 27k disagreeing are doctors, chemists, nuclear physicists, ... But do the checking yourself. There's a petition, for instance, with over 17,000 signers, but very few of them are in climate sciences (but check me on that). If your mechanic says your car needs a new belt, as do the several other mechanics you take the car to, while a bunch of doctors you know say that it doesn't, do you get the belt or not? I get the belt. Being knowledgeable (about something) isn't sufficient; you have to be knowledgeable about the thing at hand.

A different thing, if you encounter folks trying to stampede you into particular actions (whether to avert climate change, or to ignore it) is to put a focus on Where's the science? If they're going on about how if you don't do everything they say 'we're all gonna die', or if they go on about if we do do anything 'we'll all be unemployed', well, no science to either claim. Move on. This is amazingly (depressingly) effective at screening out the stampeders. The very few comments in the vein of 'this is what we understand, therefore the following action would be a good idea' you can study and decide whether you agree.

I do a number of things that are advised for climate change reduction/prevention/etc., not because of any stampeder, but because it saves me money to drive a more efficient car, have a better-insulated house, etc. If it happens that also this does good for the environment, great.

Introducing the Atmosphere

A while back I introduced the ocean. a bit. Time for the atmosphere, which turns out to be much simpler than the ocean, or maybe that just is a matter of being more subtle.

In the ocean, we have names for areas bounded (usually) by land. This doesn't work for the atmosphere, since it covers the whole earth. It does turn out, however, that the circulation itself (as for the Southern Ocean) helps divide the atmosphere. For a first approximation, little air crosses the equator. (Some does, to be sure.) So we can divide the atmosphere to northern and southern hemisphere circulations. Even though the two hemispheres are greatly different in their amounts and distribution of land and ocean, it turns out that their major circulation is quite similar.

In both hemispheres, air rises from the equator, move towards higher latitude at elevation (5-15 km, 3-9 miles up) and then sinks to the surface around 30 degrees latitude (north or south). The surface circulation is from that sinking latitude back towards the equator. This is the Hadley cell. There's a similar cell between about 60 degrees latitude and the pole, called the Ferrel cell. In between the two is not so much a cell as a storm zone.

A couple of questions I haven't seen firmly answered (I do have leads on a couple of papers, but haven't read them yet) are: Why are the circulations so similar between the hemispheres? Why are there 3 zones of circulation instead of 2, 4, 5, 75, ...?

In the vertical ... how high is up? :-) There's actually a way of approaching this by way of a different question:

What is the atmosphere made of? If we sample air all around the world, and through all levels of the atmosphere, we discover a few striking things. First, only 3 gases account for almost the entire atmosphere -- Nitrogen (N2), Oxygen (O2), and Argon (Ar). They are, in order, 78%, 21%, and 1% of the atmosphere in terms of counting molecules, and 76%, 23%, and 1% by mass. Note that these figures have been rounded, but also note that they do add to 100%. A further feature is that this proportion is constant throughout the atmosphere -- until you get to about 100 km (about 60 miles) up. Above that point heavier gases separate from lighter ones.

So that's our answer to 'how high is up?' -- about 100 km.

But back to the matter of what the atmosphere is made of. We've all heard about water (H2O), Carbon dioxide (CO2), and Ozone (O3) and how important they are. They are indeed important. But, added up through the atmosphere, they account for only about 0.24% of the molecules. Considering all gases, only about 1 in 400 molecules is not one of the big 3 of Nitrogen, Oxygen, or Argon.

Yet it is these other, rare, molecules which account for almost all the interesting processes in the atmosphere! This includes rain, hurricanes, the fact that the earth is not frozen, protecting surface life from solar ultraviolet, constructing the stratosphere, ...

Ok, the stratosphere brings us back to the vertical structure of the atmosphere. Starting from the surface, we have the troposphere. Here's where almost all the weather happens, and temperatures generally decrease with height. (So it's usually cooler in the mountains than the flat land around them.) In the stratosphere, temperatures are constant or increasing with height. Above this is the mesosphere, where temperatures go back to decreasing with height. The top of the mesosphere is that 100 km (or so) boundary. Above this, things get very different, and usually are studied by people who aren't meteorologists or climatologists. (Aeronomers, chemists, physicists instead.)

The stratosphere being a warm place, compared to the air above or below it, is because of the ozone absorbing ultraviolet. Without the ozone (and the chemistry that maintains that molecule), there's nothing to be absorbing energy to warm the layer. At most, ozone is about 12 parts per million of the molecules in that layer (0.0012 % !)

Since my first cut is always to take a look at the largest scale things, the most common, and such, we're already done. 3 molecules make up almost all of the atmosphere (N2, O2, Ar), there are 3 circulation zones between equator and pole in each hemisphere, there are 3 layers in the vertical, and the atmosphere goes up about 100 km.

To understand most of what's interesting, we have to get much more subtle. Always a fun and interesting thing to find that understanding some very small part of a big system will let us understand a lot about that large system.

The question place #1

I'll put this up as a collecting spot for questions. If you have questions about science, drop them here. Some I'll be able to answer in new posts, some, maybe readers here will be able to make progress with.