4 ms·

Is it not possible to backtest these sorts of things? If it were, I would assume results would be the first bullet point on articles like this, but I also don't

• makomk 7y ago
  The article does sort of address this for one of the models: "The model run by NCAR, one of American’s main climate-science institutions, started producing unusual data last year while trying to reproduce the recent past. “We got some really strange results,” Gettelman said. The scientists went on to try 300 configurations of rain, pollution, and heat flows—something they can do as gods of their own digital earth—before matching the model to history. But by solving that puzzle, Gettelman’s team sent future projections upward at an unheard-of rate." Basically, the backtesting failed to match reality for the recent past, they tweaked parameters to get it to fit, and that produced surprisingly high predictions for the future. I don't think that would leave them anything to backtest on, since they'd used effectively all their historical data to fit the model to.