I am convinced! The rapid rise in greenhouse gases measured during the past century is on a steeper incline than at any time in the past 800,000 years, according to an analysis of samples taken from the longest-run Antarctic ice core. Scientists from the British Antarctic Survey have reported that eight main cycles of atmospheric change occurred during this period. Actually this effect is well known, and follows a main cycle of around 100,000 years (thought to be related to changes in the ellipticity of the Earth's orbit around the sun), with shorter bouts of periodicity (20,000, 40,000 years) within this. The term Milankovic Cycle is sometimes referred to, named after the Serbian mathematician who attempted to correlate these data with cyclic factors based around the effect of the tilt of the Earth's axis on the solar energy received by the planet as it moves in its orbit over time. At each 100,000 year "peak", the Earth's temperature and atmospheric CO2 and methane concentrations rose to a maximum; however, the current levels are unprecedented, and lie outside the limits of natural variation measured throughout the 800,000 year period revealed by the ice-core. For instance, CO2 has varied between 180 and 300 parts per million (ppm), but now it is 380 ppm. Similarly, while methane levels were never above 750 parts per billion (ppb), it is now 1,780 ppb (i.e. 1.78 ppm). It is the rate of change that is most significant, with increases in CO2 never greater than 30 ppm in 1,000 years, yet it has increased by that amount in only the past 17 years!
Now, I will play devil's advocate here. Are the data taken over sufficiently short time intervals, that we may know "exactly" what the changes were immediately preceding each previous "peak" in the geological record? As I recall from previous core samples, they were not, and indeed there was a suggestion that the CO2 maximum came after the temperature maximum, with a lag of about 600 - 900 years. This implies a more complex mechanism than a simple connection between atmospheric CO2 levels and global temperatures. Frighteningly, this may imply that the full "heating effect" of the present atmospheric CO2 has yet to kick-in.
My point is that after each maximum, there has been a plummet in global temperatures, leading into what we know as an "ice-age". Could it be, as some think, that we are on the leading edge of a dramatic climatic event of this kind? I am convinced that human sources of CO2 are the most likely to account for the unequivocal surge in the levels of this greenhouse gas that the ice-core measurements show. However, will the outcome be a very hot Earth or a very cold one?
If the rise is so rapid that the Earth systems are unable to cope with it this is a very bad omen indeed. However, it may be that the systems always break down before an ice-age type switch to a cold period during which a substantial fraction of the "excess" CO2 is adsorbed. Is there sufficient ice-core data available taken say every 10 years for previous maxima to enable us to tell?
In any event, we should be cutting back on our use of fossil fuels, including "oil" to try and ameliorate the potential violence of climatic change in addition to the reason that the stuff is running out!
It is likely that climate change is going to happen whatever we do now, and we should write this into our war-plan for a sustainable society. If an ice-age is due, how will we survive? Is it likely that such an event, say involving a slow-down of the Atlantic Conveyor (of which the gulf-stream is a part, and keeps the U.K. above the temperature of Northern Canada), will be preceded by a decade or decades of unprecedented hot and violent weather? Perhaps there will be no ice-age this time (because of the unprecedented high CO2 levels) and it will just get hotter and hotter - so what do we do then? In all of these scenarios we will need fuel - hence there is no excuse to continue to waste it!
How do we continue to keep warm or cool and feed and water our populations? Localisation is the key feature, although the time may come when it is more expedient for populations to move to either hotter or colder climes in order to survive. It seems a curious notion that the temperature of a region might become a resource along with water, food and fuel, and potentially create another scramble of borders, ownership and wars to decide who is entitled to it!
An ice-age would encourage migration from north-to-south, while unabated heat will drive populations north. Water, however, will become increasingly scarce in addition to a pressure of rising population in either case; if it becomes increasingly locked-up in ice or evaporated by advancing desert.