1981 Paper's Predictions for Global Temperatures Spot-On 371
Layzej writes "The Register reports on a paper published in Science in 1981 projecting global mean temperatures up to the year 2100. 'When the 1981 paper was written, temperatures in the northern hemispheres were declining, and global mean temperatures were below their 1940 levels. Despite those facts, the paper's authors confidently predicted a rise in temperature due to increasing CO2 emissions.' The prediction turns out to be remarkably accurate — even a bit optimistic. The article concludes that the 1981 paper is 'a nice example of a statement based on theory that could be falsified and up to now has withstood the test.'"
What that really means? (Score:5, Interesting)
I am very far from being a specialist in this topic. The The Register article seems to imply that global warming must be true, given that there was ONE paper in 80s already anticipating it. That is not necessarily true. The prediction can be result of pure chance in a possibly erratic research study (I have no clue if that is the case or not). One could perhaps make an stronger statement in that direction if MANY papers anticipated global warming (possibly using different models).
Re:monkeys throwing darts... (Score:5, Interesting)
I'm not commenting on the climate one way or the other, but when you have dozens of different predictions over the years is it really surprising that a couple of them happened to hit the mark?
Well that's pretty much how science works. Lots of different people with different theories make different predictions based on those theories.
The guys that make accurate predictions the most are the ones whose theories scientists start to believe are true.
Shift to a productive debate... (Score:4, Interesting)
Prescient (Score:5, Interesting)
From the Hansen study:
"Political and economic forces affecting energy use and fuel choice make it unlikely that the CO2 issue will have a major impact on energy policies until convincing observations of the global warming are in hand."
Re:monkeys throwing darts... (Score:2, Interesting)
You're correct. What you describe is the mainstream tenured academic world, not capital-s Science. There are always some scientists out there working in the corner somewhere, unnoticed.
Test of Time (Score:5, Interesting)
"a nice example of a statement based on theory that could be falsified and up to now has withstood the test."
Just wait till we finally reach a double of atmospheric CO2 values, at which point we'll get to see if the predictions Svante Arrhenius made in the late 19th / early 20th century pan out.
If the quantity of carbonic acid in the air should sink to one-half its present percentage, the temperature would fall by about 4 degrees; a diminution to one-quarter would reduce the temperature by 8 degrees. On the other hand, any doubling of the percentage of carbon dioxide in the air would raise the temperature of the earth's surface by 4 degrees; and if the carbon dioxide were increased fourfold, the temperature would rise by 8 degrees.
Although the sea, by absorbing carbonic acid, acts as a regulator of huge capacity, which takes up about five-sixths of the produced carbonic acid, we yet recognize that the slight percentage of carbonic acid in the atmosphere may by the advances of industry be changed to a noticeable degree in the course of a few centuries.
A Pointless Anecdote (Score:5, Interesting)
So, being an avid Slashdotter, I was fairly in tune with the Global Warming debate and would often talk to my new friends about it. Every single one of them either didn't want to hear it or thought I was an idiot. They seemed to only listen when I would bring up news items lending credibility to the absence of climate change. Then they asserted there was climate change but it is natural and so on and so forth. To this day, my friend from Texas does not recycle in his home. His Korean wife has asked me not to discuss global warming around her and continually asserts it was proven wrong years ago. My friend from Texas, being quite a bit smarter now likes to talk about what we can do about it without him having to alter his lifestyle at all. The reason for it is unimportant to him, now he just accepts that it's happening for some reason and how can we put something in space that can block the sun partially while maintaining a synchronous orbit around the sun between it and Earth. It's not that that is a simpler solution than reducing your personal carbon footprint but instead it's one that doesn't require government intervention (which he views as the ultimate evil) and doesn't require him to change.
So what do you do when you read news about this, do you whip out your biggest "I told you so" font and e-mail it out to your friends until they get tired of it? I mean, I can't even politely offer to collect the cans and bottles from one of my friend's parties and take them to the local recycling center. He's almost proud of his freedom to be able to send it to the dump. So I have two options. One is silence and apathy and the other is not having any friends in this area. Silence and apathy it is.
Re:monkeys throwing darts... (Score:5, Interesting)
The idea here is, we have a rough idea of the major inputs and outputs, so scientists have to guess at the coefficients and constants. There are a number of them, positive and negative, so you can actually be wrong on every single one of them and still get the right answer. In this case, it appears he was off by 30%, which isn't a very good indication of predictive power. (Yes I know his prediction was under, but the goal here is accuracy, not who can predict the best disaster).
When I get home from work I'll have a chance to read the paper in more depth, to get a better idea of how random his guesses were. It is definitely true that in 1988 he thought his prediction was better.
Remarkably accurate for this ~this year only! (Score:2, Interesting)
Figure 6 predicts a 0.45 degrees Celsius rise from 1979 to 2012, which matches well with the Wood For Trees [woodfortrees.org] global temperature index. However, Figure 6 does not predict that all of that rise will occur prior to 1998, with a flat-to-falling trend since then. Indeed, since the model has an exponential behavior (due to feedback/"sensitivity", I'm guessing), it actually shows quite the opposite behavior, with very little rise early in the period, followed by a much greater (linearly-approximated) slope in the last decade. The conclusion is that this model got very lucky this year, and does not well reflect the underlying physics.
The greenhouse effect is real, the earth has warmed over the past 30 years (though not much, if at all, over the last 13), and human behavior may be contributing to this warming by contributing slightly to the greenhouse effect. However the model presented in this paper is not a good explanation for the details of this process, and therefore cannot be relied on to estimate the magnitude of AGW. It therefore has no value as a policy tool, never mind that it has nothing to say about the economic costs of proposed policy solutions (or even its hypothesized environmental impacts).