As recently as 10,000 years ago, much of the world’s northern hemisphere was covered with a solid sheet of ice, anywhere from 2,000 to 4,000 m thick. Most of it has disappeared - melted away since. How much energy was required to melt that mega-ice cube?
Volume of the Ice
Let’s assume the ice to have been, on average, "only" 2,000 m thick, and having covered evenly the area north of latitude 45 N. With the earth’s radius of 6,500 km, that equates to an area of 2 x 3.14x6500^2 x (1-0.7) = 6 x 42x10^6 x 0.3 = 80 x 10^6 (km^2). At a thickness of 2 km, the volume of ice was 160 x 10^6 (km^3), or 160 x 10^15 m^3, with a mass of 160 x 10^18 kg.
Energy required to melt the Ice
To melt one kg of ice (at 0 °C), an energy input of 80 kcal is required. For the entire block of hemispheric ice to melt, the energy required calculates then to 160 x 10^18 x 80 = 13000 x 10^18 kcal.
Oil equivalent
Upon combustion, one mol (0.140 kg) of decane (C10H22) – a proxy for gasoline - releases 6800 kJ, or 6800/4.2 = 1600 kcal. One kg of decane releases then 1600/0.14 = 11500 kcal.
Hence, to melt the entire block of ice, the heat of combustion of 13,000 x 10^18 / 11,500 = 1.1 x 10^18 kg (or, roughly the same number of liters) of decane would be required.
If we assume the average makeup of crude oil to be the equivalent of decane, and 140 liters per barrel, then the amount of oil comes to 1.1 x 10^18 kg / 140 = 7 x 10^15, or 7,000,000,000,000,000 barrels of oil.
Comparison with our Oil Consumption
The world uses somewhere around 85 x 10^6 barrels of oil a day. If we assume the same rate of consumption for the last 100 years, the total consumed amount comes to 100 x 365 x. 85 x 10^6 = 3 x 10^12 barrels of oil. That amount is a measly 1/2,000 of the energy provided by nature to melt the continental ice sheets. – Expressed in a different way, nature has thus provided the (extra) heat equivalent of burning some 2 x 10^9 barrels of oil per day over a period of 10,000 years to melt that block of ice.
Climate Change Implications
The disappearance of this massive block of ice over a relatively short period of time was the result of a large-scale climate change (warming) from natural causes. It could not possibly have been due to mankind’s influence; the world’s population then numbered only in thousands. Furthermore, it could not have been due to a large natural release of carbon dioxide (CO2) as the level of carbon dioxide (CO2) in the atmosphere barely changed during that melting period; it was a constant 250-300 ppm.
If nature can provide such a massive energy flux "without cause," one has to ask "has it stopped now, or is it still continuing?"
The Future
If Mother Nature keeps adding a similar amount of energy, any and all of mankind’s attempts to arrest or control "climate change" (i.e. global warming) will be in vain. On the other hand, if nature were to decide that it wants to stop adding that energy, or possibly even withdraw some of that energy, we could be in for new ice age arriving very soon. In fact, the declining number of sunspots supports the projections of a global cooling period over the next decades; even NASA says so.
