Retired software engineer. "What is that?", you may ask. It's someone who has time to blog about the weather...
By: Bogon , 11:06 AM GMT on September 14, 2009
The wrangle about global warming and climate change is a hot topic :o) at Weather Underground and in the world at large. Much of what I hear seems calculated to generate more heat than light. That bugs me. So I'm going to set aside woolly worms and blob watching for a minute and uncork a rant. Here it comes.
Global Warming versus Climate Change
There are two terms that are commonly bandied about in this debate; I want to take a look at them first. Perhaps later we can think about data. People on every side of the debate marshal data in support of their positions: charts, graphs, satellite photos, orbit calculations and so on. People on one side generally seek to question, undermine and refute the other side's data. One thing I think we can agree on, because we have a lot of data from impeccable sources gathered over many generations, is that it's a good idea to consider what you're talking about before you open your mouth.
So what do we mean when we say "climate change"?
Well, climate is about weather patterns averaged over time. I don't believe there is an official definition of how much time, exactly, it takes to characterize climate. For an individual human being a hundred years is a long time. For a society or nation a thousand years is a long time. To span all of human history, you'd have to reckon on the order of ten thousand years. Much longer than that, and you're talking about geologic time. For the purposes of this discussion I doubt that it's useful to try to define climate over millions or billions of years. Obviously weather patterns change grossly over the eons. The sun's output fluctuates; the earth's orbit weaves and wobbles; continents drift to and fro. Ice ages came and went while the human species evolved. Let's pick a thousand years as a ballpark upper limit on time span over which we may integrate weather to determine climate. That's longer than a lifetime, shorter than a geological epoch. I want to be able to say, for example, that it's subtropical in Miami and snows a lot in Buffalo. It is reasonable to make that kind of assertion based on observations recorded over the last several hundred years. We want to talk about what is 'normal' for an area. If it suddenly starts to snow a lot in Miami, then we might wish to consider whether Miami's climate is changing.
How do we draw the line? How do we decide whether weather at a particular location is normal or not? Ultimately it's a judgment call, guided by experience. You look at the record. Here's where it gets tricky: there is no unified comprehensive data set. There are shiny new records and moldy old records. There are discontinuous records collected by diverse people with different skills and motivations using various instruments and methodologies. All these data have to be collated and interpreted. Sometimes interpretation might be as simple as reading a newspaper. Or it might entail minute observation of tree rings, ice cores, or layers of sediment. When it comes to finding evidence of past climate, the definition of 'record' may be rather broad, depending on how much energy and ingenuity you can bring to bear.
Is the climate changing? You bet. It changes all the time. We have historical records of climate change. The sun, the driving force behind weather, is a dynamic star with oscillations and cycles occurring on different time scales. The earth's motion around the sun is chaotic. The interaction of the oceans and atmosphere in response to solar forcing is likewise unpredictable. We humans recognize patterns in the chaos because that is what we do. We are built for pattern recognition.
What is "global warming"?
We're talking about a worldwide increase in temperature. More specifically, in the context of the current debate the temperature increase is assumed to occur as a result of human activity.
Is global warming happening? Absolutely. Humans generate heat. They emit greenhouse gases. They change earth's albedo. The more humans there are (There are a lot! Humans are far and away the most numerous large animal on the planet.) and the more their technology advances, the more capable they are of changing their environment. Can they warm the world enough to noticeably alter the climate where you live? Probably. If not now, then soon. During my lifetime the population of the world has doubled. I can feel my elbow room shrinking. I believe that there is ample evidence that humans are affecting the climate. Your mileage may vary.
Of course, nature still holds the high cards in the climate game. It's possible that a cooling sun, or a changing orbit, or some other massive natural effect will completely overwhelm the human blip. But will it? We don't know.
Compared to the time scales over which we measure climate, we, as individuals, are ephemeral. We expect climate change to occur slowly. The globe girdling technology we use to collect, analyze and model climate data is new. We haven't had time to accumulate a thousand-year series of satellite photos. (I can remember a time before satellites. There was only the moon... then there was sputnik!) Since we don't possess detailed information about great climate-changing events, we can't really say how finely balanced the earth's climate system is. We understand that some kinds of changes are self-reinforcing. Take cooling, for instance. As the earth cools, snow and ice cover more and more of its surface. Snow and ice are white and reflect most of the sunlight falling on them. The planet's albedo increases. Instead of warming the earth, the reflected radiation escapes back into space. As a result the earth gets colder and colder. Cyberneticists call this positive feedback. If cooling goes on long enough, eventually conditions reach a tipping point, and everything changes. That is how an ice age can get started. Climatologists conjecture that there may be a tipping point for warming as well. Melting ice and snow uncover darker soil or ocean underneath, decreasing the earth's albedo, leading to additional warming, which melts more snow etc. Eventually all the ice melts, the level of the oceans rises hundreds of feet, and the weather is comparatively warm even at the poles. Both scenarios, global hot and global cold, have happened before. There is evidence that sometimes the climate can tip from one state to another within a short time, climatologically speaking, perhaps on the order of a century.
So what's all the fuss about?
We know that climate change can and does occur. We know that humans contribute to global warming. Why all the controversy?
The major sticking point, the unanswered question, is: what are we going to do about it?
A. Some people think it is criminally irresponsible to run what amounts to an uncontrolled experiment on our one and only habitable planet. They think the future of the human race (and every other terrestrial species) is at stake. They believe we should all do whatever it takes to keep the planet healthy. They counsel prudence and good stewardship. They would turn over to their children a world in as good shape, or better, than the one they inherited from their ancestors.
B. Some people seem to think that the earth can handle whatever abuse we dish out. Or they imagine that dealing with the results of unsustainable growth will be somebody else's problem. They want business as usual.
C. Some people are betting on technology. They suppose that either breakthroughs in clean technology will come in time to save the world, or that by the time this planet is too stressed to support Life As We Know It, cheap and reliable space travel will enable them to move across the high frontier. They can't be bothered to pick up their trash.
D. Some people don't think about this issue at all. They're just here for the pizza.
There you have it. If you put representatives of each of these groups into a room, you have a recipe for an argument. It's like a rule, a perverse aspect of human nature, that the dispute seems more important than the outcome. The result is that we all fiddle, metaphorically speaking, while Rome burns.
I have classified this opus as a rant, and I have done so because it makes things easier for me. I can spout my observations and opinions without supplying references or documentation. I can lay out what was on my mind full speed ahead (and damn the torpedoes!) with no lengthy explanation or background. What you see is what you get.
This entry was created in a text editor, then pasted into WU's blog window. I'm going to make a second pass through the text to add hypertext linkage in lieu of the aforementioned conscientious references, bibliography etc. Most of the links will be served from Wikipedia. Please don't construe this as an endorsement of Wikipedia, but the folks there do supply references, bibliography, sources and cross-references if you want them. You can free associate across the internet or visit the library to satisfy your curiosity, if any.
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