There has been some recent blog discussion on comparing observations and climate models consistently. Here is my effort at such a comparison using the CMIP5 models which are already available. Continue reading On comparing models and observations
This might sound like a crazy idea, but bear with me. I mean, why not? We’ve got some pretty general computer models of the climate, all we have to do is change the sign of a couple of numbers. Continue reading What happens if you spin the Earth backwards?
The time at which the signal of climate change emerges from the ‘noise’ of natural climate variability (Time of Emergence, ToE) is a key variable for climate predictions and risk assessments. Continue reading Time of emergence of climate signals
It is well known that there is considerable uncertainty in the projected response of climate models to increases in radiative forcing. However, there is also considerable uncertainty in the model simulated internal variability. Continue reading Uncertainty in temperature variability
Update (23/10/11): The full article has now been published in Nature Climate Change
Climate projections (such as from the IPCC) usually consider the question of “what will happen to our future climate”. But, this question may be more informative if it is changed to “when will it happen”? Continue reading Climate uncertainty: moving from 'what' to 'when'
There has been much discussion recently on whether GCMs participating in intercomparisons, such as CMIP3 and CMIP5, are ‘independent’. But if they are not, how does this make a difference to the uncertainty in our projections for future climate? Continue reading Uncertainty in uncertainty
Previous posts have discussed climate variability in general, and modelled decadal trends in temperature specifically. However, I should have considered decadal trends in observations as well, especially as there is a long temperature record available for the UK. Continue reading Trends in Central England Temperature
Climate models produce projections of changes in climate from the present day, but these projections have a range, or spread. A simple measure of the confidence in a forecast would be the signal-to-noise ratio, r, of the size of the projected change to the spread around that change. An important question is ‘when does the spread in the forecasts become so large that the forecast should not be used’? Continue reading When to use uncertain climate forecasts