It is possible that what has influenced the politicians is the evidence of their own eyes. Too many extreme weather events seem to be happening already in too many places. Or it could be the horrible pollution across cities in China and other recently developed countries. That will have made a difference to thinking. But the big change is in the economics.
For the first time countries across the world are seeing the realistic prospect of being able to generate and use their energy in different ways and realising that if they can invest enough in the technology then we are on the cusp of major change that will help them economically. If it does nothing else Paris puts a wall of cash behind that technological change - making it all but unstoppable.
The consequences are enormous. We have to rethink everything that we thought we knew about the way economies work and consequently about the way politics work. I have always thought that the price of oil would rise as it started to run out and the changeover to a different technology would be driven by costs. Instead what seems to be happening is that the price of oil is tumbling and part of the reason is the prospect of a major increase in supply from alternative energy. The cost of green energy generation, conservation and storage is coming down so rapidly that investors are starting to realise oil is not a one way bet and a guaranteed way to make money. Investing a great deal of money in drilling for oil in remote and difficult places like Alaska has started to look like a very bad idea. For the necessary level of investment to pay off the oil price would need to be high for decades to come. Investing in this could well be a first class way of losing a lot of money.
By contrast it now looks very tempting indeed to invest in companies producing or conserving energy in new more efficient ways. If I had a few million to invest at the moment I would be putting it into a company producing products like more sophisticated solar panels, better large scale battery storage, heat retention products such as insulating paints and liners, and efficient heaters or coolers. The size of the market for these products was already growing fast. After a Paris agreement it is virtually guaranteed to do so with extraordinary rapidity and that means increased scale, reduced costs and further improvements. There is every reason to be confident that a shift as fundamental as the introduction of the steam engine or the computer is now underway.
Oil driven technology puts a great deal of money in the hands of those who happen to own the resource. That in turn requires massive investment in defence of the ownership of that asset and puts a great deal of income and wealth in the hands of a few powerful and not particularly pleasant regimes. Saudi Arabia for one.
The future technology of energy generation is giving every indication of being much more decentralised. You can put a wind turbine or a solar panel in a lot more locations than you can drill for oil and the power source is quite affordable for poorer communities that don't need connecting to a national grid. So there is also great grounds for optimism that great improvements in the efficiency of these products will also bring more diverse opportunities for development and less need to fight to protect the property of a few very rich oil states and the companies doing business with them. Greater peace and stability looks like a very attractive proposition just at the moment.
As with all optimistic predictions it is important not to get carried away. Firstly it is entirely possible that a lot of nations will see the solution as nuclear. I continue to believe that this is a desperate gamble on high risk technology. The best scientists and technologists keep telling us that disasters very rarely happen and the prospect of them can be reduced to the absolute minimum. But the world isn't run by the best scientists and their safety inspectors. Corruption in contracting processes, cutting costs and also safety margins, poor management, and sheer bad luck are all likely to happen somewhere at some time. The frequency of disasters will be very low but the implications of even one proper full scale nuclear disaster are so enormous that we need to avoid this technology. It is naive to trust in it.
It also looks like the necessary changes to transport technology may not be happening quickly enough and that we are not yet anywhere near the point there of alternatives looking like they will become the norm in the next decade or so. Despite huge efforts from car manufacturers it isn't providing simple to switch motoring technology over to electric or hydrogen driven products. It is intrinsically hard to get an infrastructure of supply set up that equals the convenience of the local petrol station, particularly if users have already spent a lot of money buying a car. Equally you can emit more carbon in a single flight across the Atlantic to a climate change conference than you can save in a year by a complete switch over to all of the technology I've described above. As more people achieve rises in income they are going to want to travel more and the likely increase in global car ownership and travel as people get richer could well undermine all efforts.
There is a popular theory that this means that the only way of saving the planet is to massively reduce consumption and to cut down on growth. They've even give the theory the ugly title of degrowth. I am not convinced. Clearly it is no bad thing to be restrained about personal consumption but I do not believe that slowing down growth is a fair or reasonable solution to this or any other environmental problems. I don't think it is acceptable to tell the millions of people who are currently poor that they cannot live more affluent lives because Westerners have already lived that way and have messed up the planet so badly that other countries can't achieve high standards of living. Done badly "degrowth" means there is less available for us all to share and, much as I am strongly in favour of much more redistribution of wealth from the rich to the poor, I'd far rather achieve a raise in living standards by growth than by battles over the share of a declining cake. My experience of human nature is that we have a great deal to fear from extreme reactionary forces if we try and tell people they have to absolutely cut their consumption. Put simply we will never win this argument and the planet will suffer if we try and lose out. On the other hand there is every prospect of getting people firmly behind the idea of changing technology so that we can enjoy high standards of living without producing pollution, dumping plastic and cutting down forests. The challenge is not to dump growth but to change the nature of it and make sure it is growth accompanied by environmental improvements. Egrowth is better than degrowth.
A more determined programme of research into development and introduction of new technology and greater agreement between nations on how and when to introduce it gives us a real prospect for the first time of managing the scale of growth of income that people across the world want. Improved technology can create improved life chances without consuming more raw materials, cutting down more trees and polluting more of the oceans provided we take the challenge seriously enough.
There are of course many weaknesses in a technology driven solution to environmental problems and even the most serious moves towards greener technology still leaves the world with huge numbers of inequalities and living within a system that prioritises money over people. But just for once I'd quite like to put to one side all of those fair and reasonable criticisms. For the first time in many years something major has gone in a positive direction. We are far better off after this Paris agreement than we were before or could possibly have been without it. We need it signed and implemented and we can make our criticisms of the details afterwards.
As we say up north. Owt is better than nowt! I for one am very pleased that this time it looks like we are coming out with a bit of a win.