integrodifferential

It is equally obvious that it is one of MANY parametric inputs (the obviously dominant one, in my opinion) and that our ignorance of many of a near infinity of these inputs (fine grained, they go down to that damnable butterfly in Brazil, after all) requires that a HALFWAY believably model be something like a langevin equation (solved via a fokker-plank equation approach, maybe), if not a full-blown non-Markovian, stochastic, integrodifferential equation.

Willis E on Hansen and Model Reliability « Climate Audit 2006

Note well that at the CK level, solutions on the projective subspace are most generally going to be the result of solving non-Markovian integrodifferential equations with a kernel that makes the time derivative of the quantities of interest at the current time (say, the joint probability distribution for global temperatures at all the measurement stations around the planet as a function of time) a function of not only the current values of those states and other input variables describing the current values of projective (coarse grained averaged) quantities, but the values of those variables at a continuum of times into the past that has to be integrated over.

Willis E on Hansen and Model Reliability « Climate Audit 2006