EROI, or Energy return on investment, as measured by
the amount of energy attained over the amount of energy consumed in the attainment, is going down. In other words it is taking more and more energy (oil) to extract and refine energy (oil) from the earth.
In the 1930's the ratio was roughly 100:1. It took a barrel of oil worth of energy to extract 100 barrels of oil. In the 1970's that ratio was down to 30:1 and by the turn of the century it was all the way down to 11:1.
Anyone who doesn't believe that these numbers indicate an increasing concern for us (and in the very near-term, to boot) is fooling themselves and doing no favour to the rest of us.