Misperceptions About Climate Models

1. Climate models are based on uncertain science.

Wrong: The fundamental science governing climate models was developed between 100 and 200 years ago. Tracking energy in the earth system (radiation) obeys the same laws that govern radios and cell phones and GPS systems. The way water and heat work was understood in the 19th century. Uncertainties in models come from the complex interactions of these laws, not the laws themselves.

2. We can't predict the weather next week, and we can't predict the climate next year, so how can we predict climate in 50 years? 

We cannot predict weather next week or next year because we do not know fully the current (initial) state of the climate (mostly the ocean for next year). But climate is the distribution of weather, not a particular point on that distribution. Climate prediction is focused on the distribution, and that is governed by conservation of energy and mass on long time scales.


3. The formulation of climate models are the largest uncertainty in projecting the future.

Wrong: For short term prediction (weather forecasting or climate forecasting on scales out to a decade) most uncertainty comes from not knowing the current (or initial) conditions are at all locations. On timescales of a 100 years or so, the largest uncertainty in future projections is how many greenhouse gases we will emit to force the climate. The forcing is more uncertain than the model uncertainty at the global scale. In the middle, all three (initial, model, emissions) uncertainties are important.

4. The scale of climate models (100 km, 60 miles) is too big to be useful.

Wrong: there are ways of using models to understand broad climate trends in regions. Models can be downscaled to finer resolutions with statistics. And models are now being run on finer resolutions of 15 miles or less.