There have been some developments in these areas since then. #1 seems to have fallen out of favor, but it still gets dredged up once in a while. #2 has been refined to declare that the myth was invented by Al Gore (see the "ManBearPig" episode of South Park) to get attention, or by the Weather Channel to garner ratings. #3 is expanded to include every possible natural phenomenon that can influence the climate - trees that emit greenhouse gases, volcanoes, solar cycles, solar flares - and to seize on them as being the major, or even the sole, causes of climate change. #4...well, #4 is openly stated in an article in this year's Old Farmer's Almanac (which has been running annual articles by climate change deniers for the past few years). George Will tiptoes up to the point of saying it in his "Last Word" piece "Inconvenient Kyoto Truths" in this week's Newsweek:
1. Climate change? What "climate change"?
2. It's all a myth. Not happening.
3. And we had nothing to do with it, so there's no point in changing what we're doing.
4. Besides, people pay good money to travel to the tropics each year. Now they don't have to travel so far!
Was life better when ice a mile thick covered Chicago? Was it worse when Greenland was so warm that Vikings farmed there? Are we sure the climate at this particular moment is exactly right, and that it must be preserved, no matter the cost?There is a concept of a "tipping point", a point beyond which a system will begin to change at an accelerating rate without further input. Imagine putting a wooden board on a table so that it is hanging off a little. You can push that board out a little bit, and a little bit more, and a little bit more, and nothing much will happen - up to a point. Push the board just far enough and the mass of the board hanging off the table will equal the mass on the table - but the board will stay in place. A little bit further and it will begin to tip, but a degree of friction at the point of contact will keep the board from slipping off the table. A little bit more and the board will slip off the table. You can probably catch it, and drag it back, and reset the arrangement, if you're fast enough. Do that, because we'll be needing it in the next paragraph.
Now this time, line wineglasses up along the board. What happens when we reach the tipping point? Can you reset the wineglasses that smashed on the floor?
Reset the board, replace the broken wineglasses. Now add marbles, toy cars, cubes of Jell-O, a television or two, and a pack of marmosets. What happens when we reach the tipping point?
None of that has anything to do with what I'm about to say next.
I have a degree in Physics. I even did some time in graduate school. I was there to study Non-Linear Dynamics, the Physics of complex systems, known in popular literature as "Chaos Physics". I planned to have a Ph.D. by age 27 and use it to write books explaining complex Physics to the common layman. Things didn't exactly go as planned.
If you're interested in Chaos Physics, the best introduction I know of is James Gleick's book Chaos: Making a New Science. He's not a scientist, but he wrote the book after interviewing and working with a lot of people who are. In one of the earlier chapters he talks about the discovery that models of the interactions of air, land, and water that form the systems that determine our weather are irreducibly complex. That is, no matter how far down you measure data to determine the starting point for your models, there's always a level of precision below that that has an important effect. This is what's known as "sensitive dependence on initial conditions": start your calculations off using data that is precise to three decimal places, run your model for a certain period of time, and you will get one result. Start the same calculation using data with four decimal points of precision and run the model for the same amount of time, and you will get a different result. The longer you run your models - which are iterative models, where the results of cycle 1 become the inputs for cycle 2, and the results for cycle 2 become the inputs for cycle 3, and so on - the farther apart the final results will be. There is no practical level of precision that can be used to determine the inputs for meteorological models that can give results that are even marginally approximate for more than about three days out. Which is why I scream at the TV every time the weatherman gives a 5-day, or 7-day, or even 10-day forecast.
(One of the fun things with these equations is that if you start off with the right inputs you can create some really dramatic results. For example, there are lots of ways of throwing the system into a self-reinforcing Ice Age, and there are lots of ways of producing a permanent Greenhouse Effect. There are lots of ways that temperatures can flip-flop...well, chaotically. The inputs for these results are not always what you would expect.)
So, given that, is prediction hopeless when it comes to weather, especially long-term trends?
Well, to an arbitrary level of precision, yes. But meteorologists can look at trends, and records, and can compare where we are to where we've been. And computers can run thousands and hundreds of thousands of models of how the global climate will behave based on the best data available, with slight variations taken into account. These models can have their results polled and analyzed. If 99,999 out of 100,000 simulations say you're screwed, then you're probably screwed.
And that's the sort of analysis that went into the report that was presented last Friday, the same report that is saying that human activities are connected to Global Warming. The report that is being dismissed by non-scientists on the "Right" as being "not science." (Who would know better what is not science than a non-scientist?) But, really, did anyone expect them to admit that they have been wrong all along, that their delays in taking action prior to this point may have taken us beyond the point of no return?
That tipping point that I mentioned? The thought experiment involving the board, and the table, and the wine glasses, and the marmosets?
Icebergs are calving at rates not seen before. The ice caps are melting faster and faster. Things aren't just getting worse, the rate at which things are getting worse is accelerating. And human activities are pushing on the board, pushing it towards the edge of the table.
I think we passed that tipping point some time ago.
So we can try to save what wine glasses and marbles and Jell-O cubes and marmosets we can. Others will smash to the ground, beyond the point of repair. Maybe things have gone far enough that we can't stop the process.
Hang on. It's gonna be a hell of a ride.