Friday, 24 July 2015

SS Myth: Models can Hindcast. NO - they cannot - Massive Fail!

Another in our series debunking UNSkeptical UNScience's so-called Myths of Global Warming. This post debunks their "Myth" No 6.

"Models are unreliable"Models successfully reproduce temperatures since 1900 globally, by land, in the air and the ocean.

And their explanation:
Climate models have to be tested to find out if they work. We can’t wait for 30 years to see if a model is any good or not; models are tested against the past, against what we know happened. If a model can correctly predict trends from a starting point somewhere in the past, we could expect it to predict with reasonable certainty what might happen in the future.
Donald C. Morton on Dr Judith Curry's site writes:
The Validation of Climate Models 
How do we know that the models representing global or regional climate are sufficiently reliable for predictions of future conditions? First they must reproduce existing observations, a test current models are failing as the global temperatures remain nearly constant. Initiatives such as the Coupled Model Intercomparison Project 5 (CMIP5) can be useful but do not test basic assumptions such as linearity and feedback common to most models. Matching available past and present observations is a necessary condition, but never can validate a model because incorrect assumptions also could fit past data, particularly when there are many adjustable parameters. One incorrect parameter could compensate for another incorrect one. 
Again, from the SS explanation: