Prices for oil, natural gas and coal have increased rapidly in recent weeks, reaching levels not seen for almost a decade.  Since March, prices for natural gas have risen by around 150 per cent. Oil prices have risen by nearly 40 per cent and wholesale Chinese coal prices have also exploded – since August, they have risen by around 130 per cent. There are several separate but related causes for higher prices. Let’s start with the oil market – demand has increased steadily as economies have reopened, but this has happened in tandem with a modest decline in inventories, which…