In the longer run the strongest OPEC members should be able to defend their market share, even if oil demand slumps because of an economic crash. At the present price of about $90 a barrel, the vast majority of the world’s oil is financially viable. If oil prices fall by half, nearly all Saudi Arabia’s huge reserves remain profitable; the same cannot be said for America, Canada or Russia (see chart). Should climate action succeed in reducing demand to a fraction of what it is today, those low-cost producers will be the last ones left.