Distributed Computing World Climate Simulation

Burnt Offerings writes: "The BBC reports that scientists at climateprediction.com are nearing the completion and public release in late summer of a distributed computing project that simulates the world's climate from 1950-2050 AD. It seems that each user's simulation will have different initial conditions built into their runtime simulation and a single completed simulation from 1950-2050 AD takes on average eight-months (Doh!), assuming average household computing power. The results will be sent back to the project's team, where they will select the models that resulted in the 'real' climate patterns that have occured since 1950-2000. I presume they will then use these validated models to help extrapolate the world's climate from 2000-2050. Pretty cool (or should I say warm? or hot?)."

Comments

Infeasible

[Enonu]

Blame the climate changes from 1950 to 2000 on the expanded use of the automobile and unregular industrial waste. Do you think any scientist in 1950 could have known about our current situation? How can we in 2000 know about the new problems that'll creep up between now and 2050?

Spend your extra CPU cycles computing the cure for cancer or finding ET. I doubt this will prove useful.

Re:Infeasible

[Papineau]

I think what they want to do is, given the state in 1950 and what we know about the inputs (use of automobile, etc.), which models predicts correctly what we see in 2000, so that those models can then be used, along with some new inputs, to forecast what 2050 will be. Either prospective inputs, to get a glimpse of our possible futures, or actual inputs, to further validate the model or get a sharper view of the future climate.

That being said, 8 months is way too long to get something useful. I know a couple friends who reinstall their OS (and apps) in shorter terms than that, and don't really bother with bringing all data along, just some backup on CDR "in case I really want it again". I think they could at least chop it in periods of a few years, so that if you finish a "unit", somebody else can then pick up where you left. I'd like to see the completion efficiency of whole units in a few months.

checkpoints

[thelen]

If this thing takes eight months to complete, I sure hope they plan on storing periodic checkpoints of progress for each test in a central location. What happens if my machine gets hosed at four months? Is all that data lost?

Uh...good luck

[Sinical]

The information on their website says the time step is 30 minutes and that their box is 3.75 degrees longitude by 2.25 degrees latitude (or visa versa: BIG, in any event).

Therefore, how do they expect this to work -- additionally absent any outside changes in the environment?

What I mean is, how do they know if they did a good job? Perhaps if the results are all very close to the current day climate, I'd buy that they got it right, but if they have a reasonable distribution of results, how do you decide? I mean, we've been clear-cutting the hell out of forests left and right for years: do they somehow takes this into account? Heck, how do they present the geographic information about the Earth: this bit has forest, this bit is desert. I would think that this would make quite a bit of difference in results (changes in albedo, for instance).

I certainly wish them luck, but they're not getting my PC for that long without something more detailed , informationwise.

Re:Uh...good luck

[GodsMadClown]

"What I mean is, how do they know if they did a good job?"

Notice that the dates being simulated are 1950-2050. We have historical data for 1950 to the present. One of the big accepted checks for a climate model is to run a period for which you have historic data from the same initial conditions and check to see if you end up with similar answers to reality. Pretty simple, in theory. The real problem is that the cell size is just enormous. Do you have any idea what sorts of ocean current and landscape variables are contained in a 3.75x2.25 degree square? To get better results, you need small cell size and very detailed modeling of feedbacks. However, the shear range of permutations that can be attempted with a seti@home size user base is useful in and of itself.

Something isn't right.

[blair1q]

They're starting with different initial conditions and hoping that some subset results in 50 years of weather?

Shouldn't they use the last 50 years of weather as initial conditions and vary parameters of the model instead?

What they're doing is like flipping an imaginary coin 500 times hoping to match the first 250 flips of a real coin to predict the the last 250 flips (albeit in a system with non-independent trials). But then they're taking those 500 flips and matching the first 250 to weather reports (might as well be coin flips) and then imagining the next 250 flips will approximate the future weather reports. What they need to do is fix the initial conditions and modify the model (coin flips vs. rolls of the die vs. LCRNG, etc.) to find a model that approximates the dynamics of the system.

Am I making sense here? How are these bozos not just going to apply their effective innumeracy to waste a few trillion CPU hours that could otherwise have been used to do protein folding or cancer-killing molecule matching?

--Blair

Re:Something isn't right.

[gowen]

hurricanes and tornadoes, which have crucial features that won't be well modeled, if at all, by the large differential boxes they selected.

I agree the grid resolution is high, but you've missed the point. The whole *idea* is to find which parameterisation of small scale effects (eddy viscosity, ground friction, mesoscale vortices, sea ice production, add-your-favourite-here) leads to the most accurate predictions. Even if the models are flawed, this is still worth doing.

PS: IMHO, volcanic ash effects are overrated.

Re:The more I look at it... the more it sux.

[ipfwadm]

Also these people are entirely too green and liberal for my tastes. At first it is a very thought provoking idea. But these people already have preconcevied conclusions... and that isn't very good science.

On the contrary, scientists first formulate a hypothesis (in other words, a preconceived notion; human activity has led to global warming, for instance) and then perform an experiment to test it. And like it or not, global warming is occurring. The average temperature of the planet is rising, which is all that is meant by global warming. Whether or not this is the result of human action is still being contested. <OPINION>But personally, I would be very shocked if human activity has had NO effect whatsoever on the climate of the planet.</OPINION>

TKOE perhaps?

[DarkRecluse]

Why don't we quit wasting time trying to predict major climate change and start taking action to clean up our act?

Have you ever thought of how much garbage the world population puts out, trees we cut down, pollutants we flush, and general mayhem we induce?

Maybe we should be using our excess computing time into working on projects that actually might affect our environment in a positive way, rather than saying we should see what it is going to be like down the road...we all know what is going on here, and I'm not talking about global warming.

Its not the effect of global warming that is our problem right now, but the effect of our blatant misuse of resources and obvious disregard for the earth. Do we not live on this planet with the environment we are destroying...I don't think you need to be a very good scientist to realize that when the environment is decimated, we will be hard pressed to survive...

I guess everyone has some idea that God is going to come and fix everything for us, so we don't have to worry about cleaning up...hey, why don't we all call our mommys and see if they will do our work for us...why don't we own up and say, "Holy shit, I don't want to take the chance that my children are not going to grow up because I ruined their world for them." What is our general purpose in life besides taking up space, making money, and destroying the environment?

The world is a big place, but eventually our actions are going to reach around to spank us, just like our mom's did when we were bad...except it won't be a spanking we live through:/

I invite everyone to spend their 8 months attempting to exact reform in our environmental policies and personal resource use, rather than hoping your computer will somehow figure it out for you.

Extrapolation not pratical with chaotic systems

[lkaos]

As one poster has pointed out, weather is a chaotic system (and climate is also chaotic by definition).

Chaos is gravely misunderstood though so let me real quick through in my explaination for why this experiment will just generate FUD.

Chaotic equations are chaotic not because of the number of variables involved but because of the interdependency on themselves (each iteration requires the former iteration). This leads to extreme sensitive dependency on initial conditions (a.k.a. the Butterfly Effect). I should have probably emphasized the word extreme because even the slightly deviation will produce dramatically different results.

Even the best climate prediction algorithm would be crap if the initial condition was off by 10^(-20). The fact that we cannot measure temperatures exactly means that we could never feed a perfect initial condition.

Chaotic equations do have a given period before divergence gets extreme when initial conditions are altered. The original equations that Lorenz used (the pioneer of weather forecasting and the father of Chaos theory) showed divergence after about three days (which is why five-day forecasts still suck to this day).

I find it very hard to believe that these folks have developed an equation that doesn't show divergence for 100 years. Not to mention the fact that the number of initial conditions are much larger than the project makes them out to be.

Summary: Some PhD is looking for research money and figures that mixing "scientific" proof for global warming, chaos, and SETI-style distributed computer has to be good for a couple million at least.

Re:Extrapolation not pratical with chaotic systems

[nairolF]

What I'm about to emphasise has already been pointed out by another poster, but I'll elaborate a bit. What you have written about the butterfly effect etc is correct. And irrelevant. Nobody is trying to predict the weather for the next 50 years, but rather the climate.

Here's the difference. To predict the weather would mean to give the exact distribution of temperature, rainfall, wind etc at a certain date. This is what the weather report after the news is all about. This cannot be done reliably more than about 3 days into the future, because the system is so chaotic.

The climate is a different matter. It's basically an average of the weather. What they want to predict is things like the average temperature for period 2000-2010 in North America, for example. Over long periods (centuries or more), climate seems to be chaotic, too. It is certainly at least partially chaotic on smaller timescales, but there should be trends that are more or less predictable on medium timescales (decades?).

For example, if there are more greenhouse gases in the atmosphere, then this has an effect on the average weather, so one might expect average temperatures to rise. But even this is not yet completely understood. For example, increased levels of CO2 might increase cloud formation, which might increase albedo, and hence decrease the temperature. This is not yet completely understood, not because the subject matter is inherintly chaotic and thus impossible to understand, but rather because the science of climatology is not yet sufficiently advanced. This is precisely the point behind this project - to advance our understanding in climatology, so that we can better understand the effects of greenhouse gases, for example. By no means does this justify the American energy policy of sitting back and happily burning fossil fuels with gusto, until the scientists are 99.8% sure that it was a bad thing and now it's too late. That's a bit like Russian roulette: "The scientists can't yet prove that this chamber is loaded, so we might as well pull the trigger".

To sum up what is known so far: increased levels of CO2 (and other "greenhouse" gases) has a very real effect on the climate. Exactly what this effect is, is not yet 100% sure, but it seems most likely to raise the temperature. On the other hand, the world average temperature has increased dramatically over the last few decades, correlating strongly with rising CO2 levels. Of course, there are natural climate fluctuations, so this could still be a coincidence. We haven't proved with 100% certainty that our increased emissions are responsible for global warming, but it seems very likely. That is why we should try to do something about it.

In summary: Global warming is a very real threat, and not just to some unheard-of third world countries. It affects you, Americans, too. Yes, you! Hence this project is very important and potentially very useful. I hope they get a lot of support.

Re:end result

[Aphelion]

Clever, but we're talking climate here, not weather.

Re:Climate and weather

[streetlawyer]

But does any chaotic system exhibit such behavoir??`

Yes. In fact, any system which displays locally nonlinear disturbances in a globally linear function will do so.

The mere fact that climate is study of average weather is irrelevant to the system at hand.

No it isn't. It should immediately alert you to the possibility that climate might be more predictable than weather. Averages always have lower variance than the underlying data.

A chaotic system will by definition exhibit divergence either way with a slight change in initial conditions

This isn't a rigourous definition you're talking about here, and your definition doesn't prove your point. A chaotic system might exhibit divergent behaviour, but that doesn't necessarily require that the divergence be either permanent of large in relation to an underlying linear trend. For example, if I take the output of a nonlinear oscillator and add it to the signal for Radio Luxembourg, I can make a system which is "chaotic" in the sense that its local behaviour is divergent in a nonlinear way dependent on small variations in initial conditions. But I can still extract a useful signal from my system by applying the right filter.

Re:INFORM yourself with the FACTS

[Cally]

AFAIK: It's a UN organization that is the center of research.

Close... the IPCC was designed to collate all well-reviewed, reliable, statistically sound studies done around the world, and describe the consensus of opinion amongst researchers in the field.

RANT MODE = "ON"

The idea was to prevent scum-sucking American corporations from buying the US Government (by convincing the typical Merkin in the street) and preventing the measures required to help allleviate the threat, from being introduced. Of course we (rational human that is) reckoned without the extraordinary phenomena of Gee Dubya. The US is now storing up /vast/ amounts of resentment around the world, even in places like Europe where we have traditionally been sympathetic to their values. Since the US started bullying respected heads of world bodies out of office -- well let's just say I don't have ANY respect for the current Administration, and I just hope the rest of the world aren't confusing the actions of a handful of corrupt, hyper-rich elite types who run America, with the actions of those unfortunate enough to live there and get brainwashed by all the anti-science propaganda. You see this here on Slashdot whenever a climate change story comes up. It's sad it is to see otherwise intelligent people talking *complete bollocks*, seemingly completely unaware that they've been brainwashed by oil companies.

Better luck in 2004.