Re: Model validation?
How are they going to validate that climate model? There's been a huge amount of climate research and modelling over the last decades but there's still a significant amount of discrepancy between different models.
Usual way is to test SimEarth against reality. So climate models can be initialised to the past, then run and compared to say, the last decade's actual weather. So a combination of 'hindcasting' to predict the past, or reanalysis to compare past model predictions against reality.
But there's an interesting video on global warming simulations here-
Err.. I mean here-
With Vicky Pope giving a Royal Institue presentation. She has.. interesting views wrt climate*, but the RI channel's worth a sub because they have all sorts of interesting lectures.
And what they are planning to do with DestinE seems like an order of magnitude more complex than what current climate models achieve.
Yup, hence wanting a supercomputer an order of magnitude larger than a lot of current climate models. Which by their very nature are very crude approximations. It's 'easier' to do UK MetOffice or ECMWF forecasting because they're either focusing on a small geography, or a short time frame, or both. So ECMWF might forecast out to 10 days, with probability narrowing as time passes and the forecasts are pretty good.
Climate models then try to make ECMWF-style forecasts decades or a hundred years out. So their Sim-Earth is broken down into large grids, eg-
Typical AGCM resolutions are between 1 and 5 degrees in latitude or longitude: HadCM3, for example, uses 3.75 in longitude and 2.5 degrees in latitude, giving a grid of 96 by 73 points (96 x 72 for some variables); and has 19 vertical levels. This results in approximately 500,000 "basic" variables, since each grid point has four variables (u,v, T, Q), though a full count would give more (clouds; soil levels). HadGEM1 uses a grid of 1.875 degrees in longitude and 1.25 in latitude in the atmosphere; HiGEM, a high-resolution variant, uses 1.25 x 0.83 degrees respectively.
So very low resolution, and not many variables simulated. So having a more complex model with say, a 1km grid with accurate terrain modelling should allow more complex (ie more realistic) climate simulations. But still not enough to simulate what might happen to wind-driven weather/climate effects, if you raised a 3m high dyke around a square kilometer of land.
*As in she's a true believer, and the Hadley models run hotter than reality. Wonder if that's because they exagerate the climate sensitivity of the atmosphere wrt CO2? In the RI vid, at around 18mins, you can see she's totally convinced that corrrelation = causation.