At Rio Tinto's investor conference in Sydney last week Sam Walsh, respected chief of iron ore at the world's number two producer of the commodity, showed two slides that neatly sum up supply and demand in the iron ore market.

Demand for ore from China – the main driver for the market – will continue its steep climb for the rest of this decade and into the next before peaking around 2030:

While consumption will stay robust over the next several decades, supply continues to lag behind as competition for labour, energy and project financing increase, approval processes lengthen further and costs in remote areas continue to escalate.

The graph below shows just how wide the gulf is between plans and execution:

Walsh says this shortfall will be made up by Chinese domestic supply in the short and medium term.

And mining iron in that part of the world certainly isn't without its challenges.