Not far from the road that the Romans called Ermine Street and we more prosaically call the A10 is a field strewn with rounded flint pebbles. These formed on a tropical beach 55 million years ago: Hertfordshire-by-the-Sea.
Above the field stands a copse. The farmer has not sought to bring it under the plough, and there is a good reason. The wood is pitted with Roman and Stone Age excavations. Our ancestors quarried hard patches of the beachrock, cemented by silica, at a time of exceptional global warming 55 million years ago. The Hertfordshire puddingstone was used to grind corn.
Grinding corn with puddingstone querns was more important to the survival in that area of our Stone Age and Roman ancestors than oil is to us today. You have to eat: you don't really have to consume hydrocarbons by driving up the A10 and flying from Stansted to Lanzarote - although that can be fun in the right company.
The former head of Opec, Sheikh Yamani, once said that the Stone Age did not end because they ran out of rock, and there is indeed unshaped puddingstone to be found. The Stone Age ended because people with brains as good as ours developed new technology and adapted to it.
We shall never know their names, but those of our present-day leaders who have the conviction and courage to act on the message written in those 55 million-year-old rocks will never be forgotten.
What is that message? While the flint pebbles were being rounded on the hot shores of Hertfordshire, an episode of dramatic global climate change was being recorded in deep-sea sediments on the ocean floor. We can now read that record 55 million years later, using the recently established division of that part of the geological timescale into thousands rather than millions of years. This brings the story on to a human timescale: we are thereby led to some uncomfortable and implacable conclusions about our current use of the planet.
It is commonly said that our present-day release of carbon into the Earth's atmosphere is an uncontrolled experiment with an unknown outcome. That is not really true. Fifty-five million years ago there was a release of fossil carbon comparable with that on which we have now embarked. This was long before we were around to light so much as a camp fire - so we didn't do it, but now we know about it. Although we cannot predict with complete confidence the outcome of our own experiment, the main effects of the 55 million-year release of fossil carbon provide hefty clues to what is likely to happen. This observational science requires no computer- generated models to carry conviction.
Earth became a lot warmer 55million years ago. Even on the deep ocean floor, temperatures increased by several degrees centigrade. The boundary between the Palaeocene and Eocene epochs is defined by the resulting extinctions in the fossil record.
Warming of the oceans caused their advance on the land, and they became notably more acidic and received large volumes of carbon as the released gases were recycled. It was well over 100,000 years before the planet returned to something approaching its previous state.
The trigger for the 55-million-year- old event remains a matter of active research. Nonetheless we know enough to assert that the whole episode may plausibly be regarded as an earlier and complete version of our own present-day dumping of CO2 into the atmosphere. A global event that is a threat to the survival of a highly specialised species such as Homo sapiens is not something we would wish to provoke through our own agency.
The oil industry is widely perceived to be a significant part of the problem. The rapture of those who discovered, and recovered, the spectacular wealth from the North Sea must now be tempered by the realisation that they are responsible for starting a piece of unfinished business with the Earth's carbon cycle. Petroleum geologists and engineers may not feel particularly in need of redemption, despite the obloquy dished out by many environmentalists. But if they are abashed, help lies close at hand, in their very own reservoirs - and elsewhere underground.
We can put the fossil carbon back - at a price. As well as considering the future price of a barrel of oil, the prospective value of a tonne of carbon put safely back underground becomes crucial. At least some of the technical and commercial skills required to produce oil and gas are comparable with those needed to inject and store CO2.
We do not have the luxury of choosing between consuming less fossil fuel on the one hand, or carbon capture and storage on the other. We need to do lots of both, to have any hope of holding the level of carbon dioxide in the atmosphere at (say) 550 parts per million (ppm) by the middle of this century. At present oil production stands at about 80 million barrels a day. Depending on how much you compress the CO2 before injecting it, you could achieve some 20 per cent of that 550ppm target by pumping 80 million barrels of CO2 underground each day.
Those of us who buy the oil industry's most useful product do so to feed the engines of aircraft, ships and cars - which do not lend themselves to easy CO2 capture. However, capturing fossil carbon at coal-fired power stations is simpler. The storage of their CO2 probably provides the best prospect for using the oil industry's skills to help to meet our stringent targets.
And why should the oil industry not seize this opportunity to develop existing technology? True, pumping waste into long-term storage is not what we veteran frontier explorers are used to, with our techno-gambler culture of high risk and high reward. This would be a future service industry, with a price per tonne for all the carbon safely stored. The dull psalm of duty would appear to replace the trill of pleasure - but that is to set the technical challenges too low. The geology and engineering involved are interesting enough to quicken the blood of skilled young people. The task could be tackled properly between now and 2050, with every prospect of technical and commercial opportunity for the UK.
One thing is missing, which only the most determined action by our leaders can provide. That is the establishment of policy and regulation that puts an appropriate and fungible value on a tonne of carbon. Simply that: there need be no officious dictation of choices of action within such a global framework. This is one area where the market really can do its work.
Which of our leaders will have the guts to establish restraint in per-capita output of carbon as a social good, on a par with the provision of health services and education? Could it be a combination of President Obama and Prime Minister Brown, working with China, India and others? We have received an important 55 million-year-old message from a warm planet. We can understand it and we should respond with conviction.
Bryan Lowell, a senior research fellow in earth sciences at Cambridge University. An extended version of this article is published in Geoscientist.