Slashdot Mirror
How Well Do Our Climate Models Match Our Observations?
bunratty writes "According to recent articles by Roy Spencer and John Christy, our climate models have done a poor job of predicting warming due to humans burning fossil fuels. They claim that we've observed only a fraction of the warming they predict. But when I look at the source they claim to use, the State of the Climate in 2012, I see that it shows a warming of 0.7 degrees Celsius worldwide since 1980, close to the 0.8 degrees Celsius warming predicted by the climate models. Take a look at the data for yourself. How well do our predictions match our observations?"
That's because you are looking at climate models calibrated against that data that you are comparing to. Circular logic.
If you look at the predictions from past IPCC reports, very few of their predicted temperature profiles match the later observed conditions. That is a failure of the models' predictive power. That doesn't mean there isn't warming, just that the Earth's climate is a more complex system than can be accurately simulated with modern computing hardware.
I can't speak to the accuracy of historic weather data or modern weather models, but I can say this:
Global Warming / Climate Change (pick one, please) alarmists do themselves an incredible amount of damage when they do the following:
1. Grossly exaggerate predictions and base everything on the worst case they can find.
2. Manipulate charts to make changes look far more significant than they really are.
3. Instantly ridicule anyone who disagrees with them on anything, even if that disagreement is valid.
Let's say for the sake of argument that all of the predictions from these weather models are 100% accurate, all of the research and data is correct, and that the climate is indeed warming because of CO2 emissions, and that the climate will warm 5 Celsius degrees in the next 200 years. Let's pretend that the science is completely perfect.
Even if all of that is true, you will find a lot of people who won't even bother listening because they remember crazy predictions like "New York city will be underwater in 20 years!" and "We're all going to be cannibals! Cannibals, I say!"
Do you see why so many people don't listen to those who are trying to push human-caused climate change?
Politics needs to be taken out of the equation. Completely. Everything needs to be 100% transparent. The science needs to be broken down in ways the average person can understand. Even if that happens, it will be decades before the damage the global warming alarmists have caused can be reversed.
Love sees no species.
Small fluctuations in local weather are much, much, much, much more chaotic than large fluctuations in global climate. This is hardly unique to atmospheric sciences.
Lets us an IT analogy, lets say you manage a large data center and your head of IT comes up and says something like this:
"Over the next 5 years, 15% of the hard drives in this data center will fail. We need to take these basic precautions."
Your response would be like:
"Why on earth should I trust your estimate for 5 years from today when you can't tell me exactly which servers will fail within the next 6 months!?"
And then you'd get angry at him 5 years down the road when only 14% of the drives failed and be all like:
"See! I told you there was nothing to worry about!"
I don't think it should be surprising if changes in climate affect the behavior of people in areas. If food becomes more plentiful I bet crime goes down. If food and water become more scarce I bet it goes up. If the weather patterns are changing surely some areas are going to get drier and some are going to get wetter. Also, as events become more extreme all the extreme weather events you sited are likely to happen more often too, don't you think? So you're right, global warming almost certainly is doing all those things.
I don't see why it's controversial to think that. Even if you don't think people have anything to do with changing climate all those effects are obvious outcomes of it changing, and I don't think many people actually doubt that it is changing.
Look back before that, the period from 1950-1974 (approximately). How well do the models match there?
Cherry picking is bad science. You have to look at the whole record from the start of the Industrial Age... and the models haven't been particularly good.
That's not an anti anthropogenic global warming statement, by the way. It's a "science is hard and you can't understand a subject after ten minutes of reading" statement.
#DeleteChrome
When it comes to modeling, "predicting" old data is actually an invaluable technique for developing useful models. For instance, if you're working with machine learning algorithms, it's typical to segregate your data into a training set and a test set (sometimes an additional validation set as well). The training set is used to teach the machine learning algorithms, thus establishing a model. You then take that model and run it over the test set to see how well it matches.
Put differently, rather than creating a model from all of the old data (which, as you said, is trivial and not really that impressive), you put yourself in the shoes of a 1970s scientist and try to use the data from only up to that point to create a model that will work for the next 40 years. You then get to fast forward 40 years and see how you did. If you didn't get it right, you go back and try again.