Complex Multiscale Systems (CMS) play a crucial and wide-ranging role in daily life. A problem of CMS is that they represent high dimensional computational problems which are beyond  most standard computational methods and when tractable often show unfavourable effects such as oscillations, finite time blow-up or unphysical solutions. Often, available macroscale models are not sufficiently accurate whilst the corresponding microscale models are too inefficient and/or result in excessively large amounts of data. Computational approaches attempt to combine these two viewpoints in the hope of achieving a reasonable compromise between accuracy and efficiency.