Timeline of atmospheric model resolution
Europe is looking nicer and nicer every year (source):



This is a little bit out of date, since AR5 is already out - the dates for the first 4 IPCC reports were:


IPCC First Assessment Report, 1990
IPCC Second Assessment Report, 1995
IPCC Third Assessment Report, 2001
IPCC Fourth Assessment Report, 2007
IPCC Fifth Assessment Report, 2014


And an updated image for AR5 looks like this (both of these are AR5 model resolutions) (source, p145):



And that same PDF has another representation of increasing complexity, where cylinder height indicates complexity (source, p144):