This is an interesting take on the figures.
http://www.vox.com/2015/1/22/7871947/oxfam-wealth-statisticAs to the second part of your post, I don't think, and doubt that Oxfam thinks, that there is an easy set of actions to take. Rather if the trend of the figures is going in this direction, we probably have to look to change something or understand the affects of it. The complexity of actions in the area of global economics and the interaction it has with politics is, I would argue, past any possibility of grand plans.
I think we can only concentrate on tactical solutions here, looking where there are specific areas of control, in national terms aiming to support those in most need, and in terms of the figures used in the Oxfam headline, that's going to be looking at reducing personal debt, and the property bubble in parts of the country.
Globally we can look best to reducing conflicts, as if that were easy, and dealing with areas ravaged by climactic extremes. That said, other ways of looking at figures point to a glass at least half full, if not getting fuller.