Royal Dutch Shell's former chief economist has warned that the world is seriously overestimating how much more oil can be squeezed out of the ground.
In a scientific analysis published in Wiley Interdisciplinary Reviews: Energy & Environment, Michael Jefferson says there's evidence global production of conventional oil plateaued and may have even started to decline from 2005.
He goes on to argue that the five major Middle East oil exporters altered their definition of "proven" oil reserves from 1984, resulting in an apparent (but not real) increase in their proven oil reserves by around 435bn barrels.
Hard-to-extract Venezuelan heavy oil and Canadian tar sands are also included in conventional estimates of the world's oil reserves, inflating the figure by another 440bn barrels, Jefferson added.
Put bluntly, the standard claim that the world has proved conventional oil reserves of nearly 1.7 trillion barrels is overstated by about 875bn barrels.
This would means it's actually around half the figure typically touted by respected organisations, such as BP and the US Energy Information Administration, which say that the world could potentially recover nearly 1.7 trillion barrels of the black stuff.
Oil prices have tumbled from over $110 per barrel in the middle of 2014 to around $45 today, dampening concerns that "peak oil" could one day lead to brutal price rises.
But Jefferson says companies' cutbacks to oil exploration across the world means that this nightmare scenario should still be a key concern for energy policymakers.
Thus, despite the fall in crude oil prices from a new peak in June, 2014, after that of July, 2008, the ‘peak oil’ issue remains with us, and broad economic recovery combined with the consequences of recent oil exploration and production cut-backs will bring back further major oil price rises.