This is arguably the most important year in human history. The grandiose invites suspicion, so the previous sentence was written reluctantly. But ideas do not seek permission before they enter your mind, nor are they always the most welcome of guests.

The idea that this might be the most important year in human history was prompted by the headlines that greeted the New Year. War and recession, tragically familiar sources of human misery, dominated. Yet it was what was missing from them that provoked my unwelcome thought.

In December, a meeting on an issue far more important than war or recession to the future prosperity and security of literally everyone on earth will take place in Copenhagen. Yet, nowhere did its prospects make the front pages. Terrible though they are, we know that consequences of war and recession pass. Climate change is forever.

The punctuation of history is marked by the names of the places where order was restored after chaos had prevailed – Westphalia, Versailles, San Francisco. It is not an exaggeration to say that what happens – or does not – in Copenhagen in December will shape human destiny more deeply, and for longer, than any of them.

The reason for this is the unique nature of the climate problem. We know that dangerous climate change is a threat to the fragile film of order we humans have built around the chaos of events and call “civilisation”. We know, because Europe’s political leaders told us, that a rise in global average temperature of more than two degrees Celsius is dangerous. We know from our scientists that greenhouse gas emissions must be moving downwards globally by 2015 if we are to have any chance at all of staying within that limit.

Once a given concentration of carbon is in the atmosphere the climate it drives is inexorable, even if it takes decades or more to fully express itself. In the most literal sense, the sins of the fathers will indeed be visited on their sons and daughters and well beyond the third and fourth generation.

Climate change does not suit us. We have little experience with the irrevocable and dislike exacting time limits. The nature of the climate is such that the future cannot redeem today’s mistakes. We have one chance, and only one chance, to reach a political agreement to reduce global carbon emissions in time to stay safe. This is the year in which we take that chance.

Compared to the diplomatic effort needed to achieve success in Copenhagen, that required for a final settlement in the Middle East is small. But there is no sign that an effort on the required scale is yet being made. Compare the amount of media coverage, and intensity of political effort, given to the Middle East to that accorded to climate change.

This is not to diminish in any way the magnitude of that tragedy, nor to argue that less should be done to address it. It is rather to point out the classic human error of allowing the more immediate to obscure the more urgent. History does not have an agenda on which items can be prioritised. Either you deal with the events it throws at you or they deal with you.

We humans do not learn easily. We try and fail and try again. Our progress is incremental. We are prone to repeating our mistakes. Too often, we are content to let the future redeem the mistakes of the present.

No leader will want to come away from Copenhagen saying they failed to solve a problem they have recognised as the most serious facing humanity. But the appearance of success will be easier to achieve than the substance. It will consist of words and the less the success the more interpretable the words.

To get emissions on a downward path by 2015, 200 nations must agree to so coordinate their energy policies as to build a carbon neutral global energy system by 2050. This will require the greatest cooperative endeavour in history. Agreement in Copenhagen is the key to the lock on the door to that 40-year endeavour.  The political conditions needed to turn that key are not yet there. We have this year to build them.

Deeds rather than words will play the biggest part in building those political conditions. US president Barack Obama has pointed the way with a stimulus package aimed to deliver economic, energy and climate security together. If the European Union and Chinese stimulus packages are also well designed then US$1.5 trillion dollars will be spent in ways which really will begin the transition to a low-carbon energy system.

Most of the world has played a far smaller part than the OECD countries in creating the problem. Their reluctance to act is understandable, if unwise. Without significant financial help from rich countries to meet the cost of adapting to the climate change to which they have been committed by others, and to help with building their own low-carbon economies, they will be unable to support the necessary agreement. We are talking tens of billions, not millions.

Words will matter too. But the words that will count most are those of political leaders, not official negotiators. Count the number of times a month presidents and foreign ministers are in the media talking about climate change. Note the number of times they hold press conferences on the issue. If they are not going up month by month, we are failing.

Climate change is a bad problem that is getting worse. For the moment it remains manageable. Pretty soon it will become unmanageable. We already have both the technology and the capital to solve this problem. What is uncertain, and will be determined this year, is whether we have the political will to do so.

I grew up in a world engaged in another long-term, large-scale cooperative endeavour. It spent billions of dollars on building weapons it hoped never to use. When they became obsolete it threw them away and built even more sophisticated and expensive weapons which it hoped never to use.

We did that for 50 years. Eventually the world really did become a safer place. The threat of climate change to the prosperity, security and well-being of everyone on the planet, especially anyone under 40, is far more certain than was the threat of the Cold War going hot. Maintaining climate security in the twenty-first century will require at least as big an effort as maintaining peace did in the last century.

Tom Burke is a founding director of E3G, an environmental policy adviser to Rio Tinto plc and a visiting professor at Imperial and University Colleges, London.

 Homepage photo by Oxfam International