The straight forward answer would be to say…lesser consumption leads to lesser demand leads to lesser production results in lesser green house gasses and in turn a cooler earth.
But digging a little deeper we find that the reduction in production is OPEC’s way to ensure that the Oil price atleast staibizes, around $45 mark if not march towards its recent glory.
So if falling prices are the motivation to reduce production then lower prices should also result in an increase in consumption, albeit with a lag. The general consumer is cautious given the recent super spike in oil.
If the prices remain subdued for a fairly long time, the consumers are bound to return to gas guzzling vehicles and heavy energy use.
Though we should remember that this time around there have been substantial investments and initiatives towards alternative energies. These should start to become commercially viable in a few years time (hopefully by the time next oil spike is ready to happen).
What we do not know is that how these alternative sources of energy would impact the global warming. In a few years time we might realise that the energy harvested from the oceans impacts the ocean currents which in turn adversely effects the weather pattern thereby increasing the global warming. There could be similar undiscovered effects using the nuclear energy, wind power, hydro power etc.
So if you want a “cooler” earth, reducing energy consumption is the only long term viable option!