http://www.bbc.co.uk/sn/hottopics/climatechange/moreaboutexperiment1.shtml
Distributed computing and climate prediction The BBC have teamed up with Oxford University to conduct the world's most ambitious climate modelling experiment. We want to do better than the world's supercomputers, using a technique known as distributed computing. How does distributed computing work? Modern home computers can perform billions of calculations a second. Most of the time, that's far more power than the average user needs - so even though you're working hard, most of your computer is lying idle. Distributed computing projects make use of this spare computer potential. All you need to do is install the correct software, and your computer should take care of the rest. The programme automatically manages your computer's processor, so that programmes you are running get priority. Your computer only works on the experiment when you're not using the processor for something else. Distributed computing is a particularly valuable tool for scientists who have large amounts of data to analyse, or who are modelling very complex systems like the Earth's climate. Why is climate prediction so complicated? Predicting global temperature change is hard, even though the principle sounds easy. In simple terms, energy reaches Earth from the Sun. Some of it is simply reflected. Some is absorbed and then re-emitted. If the amount of energy that leaves the Earth is the same as the energy that arrives, then temperature stays the same. If not, then the Earth's temperature changes. However, a huge number of factors affect how much energy the Earth reflects and absorbs. How much of the planet is covered in clouds - and what kind of clouds are they? How much ice is there at the poles? And of course, the amount of so-called greenhouse gasses like carbon dioxide play a role too. All these factors make for an incredibly complex calculation. However, there's something else that makes climate prediction even harder. This is the existence of what we call feedback mechanisms. What are feedback mechanisms? In relation to climate change, a feedback mechanism is something that changes as a result of climate changes, and itself makes climate change happen more or less quickly. For example, heating the Earth could make the ice caps melt, which could mean that less of the Sun's light is reflected back into space, which could in turn cause the Earth's temperature to rise even faster. Some feedback mechanisms could slow climate change - some could accelerate it. Either way, they make prediction harder and mean that scientists need to run many more models to get a feel for what is likely to happen. So why do we need so many people? This experiment uses a computer model to try and calculate what the climate will be like in the future. However, small changes to the model can have large effects on the predictions that we get. There's only one way to get around this problem. If we run just one model, we have no idea how accurate it is. But if we run many thousands of models, we start to see patterns emerge. Some might be wildly inaccurate and predict warming or cooling much more severe than we are likely to see. But if a significant percentage of results fall within a smaller range, we can start to get a feel for how the climate might be changing. And of course, it's not just about the state of the planet now. The biggest question of all is the effect that we are having on the climate. What happens if we continue to pump out greenhouse gasses at the same rate as we are today? What happens if emissions to grow? And how much do we need to cut emissions by to make an impact on global warming? To get the most accurate answers to these questions, we need as many people as possible to run climate models on their own computers. What will my computer do? When you start the experiment, you'll be given your own individual climate model. Your computer will start in the year 1920 and calculate the climate, year by year, right through to 2080. Calculating the climate for the 20th century might sound like an odd thing to do. However, if your model's prediction for 2006 is very inaccurate (for example, if your whole world has turned to ice), then we know the model you are running is not a good one. But if your model has done a reasonable job of predicting 20th century climate, we know it's worth continuing with. Once your individual model is finished, it will be sent to Oxford. There scientists will assemble everyone's models to make the most accurate climate prediction they can. We'll be reporting our findings in a special programme on BBC Four. _______________________________________________ Biofuel mailing list Biofuel@sustainablelists.org http://sustainablelists.org/mailman/listinfo/biofuel_sustainablelists.org Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Search the combined Biofuel and Biofuels-biz list archives (50,000 messages): http://www.mail-archive.com/biofuel@sustainablelists.org/
