It seems that the climate of our planet is reverting rapidly to that which has persisted for much of the last 300 million years. Average temperatures and sea levels were higher, there were no polar ice-caps and temperature differences between poles and the equator were lower. The rate of this reversion, certainly in so far as it is connected with greenhouse gases, is being accelerated by humans and their activities and to such an extent that their must be a risk of "overshoot" into a situation which is entirely new.

John Jackson chairs the law firm Mishcon de Reya, is a director of openDemocracy and History Today and is on the committee of Unlock Democracy

Among John Jackson's articles in openDemocracy:

"Write the constitution down!" (17 February 2005)

"A democracy in trouble" (1 March 2006)

"Alice Wheeldon and the attorney-general" (17 April 2007)

"From deliberative to determinative democracy" (15 October 2007)

The fossil record gives us some idea of what life (and there was a lot of it) was like at different points in those past warmer times but little idea of what it will be like this time round with the present configuration of continents and oceans and humans - a very recent and significant arrival - continuing to use the planet and its resources in a destructive and predatory way.

The significance of humans is brought out in the United Nations Human Development Report 2007-08, released on 27 November 2007. Put starkly, there are already too many humans on the planet who, in the pursuit of our material aspirations, are putting growing demands on its finite air, land, water and mineral resources. We are doing so in an inefficient and wasteful way. Moreover, even if that problem is addressed by discipline and scientific advance (e.g. via GM technology and nuclear power), it is probable that, if every human being is to have what he or she regards as a fair share of resources to meet reasonable material aspirations, there is simply not enough to go round.

The entirely reasonable attempt by the "have-nots" to catch up with the "haves" and the unwillingness of the "haves" to give up what they have taken (let alone cease demanding more) is what is driving climate change, water shortage, land degradation and diminishing biodiversity. Nobody in their right mind believes that this impetus can be wished away. It will continue. Some of the damage already done is, for all practical purposes, irreversible. Further, it has "knock on" consequences of its own. Like the sorcerer's apprentice we cannot stop what we have started. The broomsticks have lives of their own.

If left unchecked and out of control the combination of all these adverse developments will put at severe risk the survival of human and many other species. And possibly quite quickly. It was not difficult to foresee most of this and there has been much sweeping under political carpets. Even given some present willingness to be honest with ourselves, it is more difficult to see what can be done about it.

Also in openDemocracy, David Steven's blog from the Bali climate-change summit opens our new Global Deal partnership with E3G

Plus....openDemocracy writers debate the politics of climate change:

John Elkington & Geoff Lye, "Climate change's right and wrong fixes" (2 February 2007)

Dougald Hine, "Climate change: a question of democracy" (2 March 2007)

Andrew Dobson, "A politics of global warming: the social-science resource" (29 March 2007)

Oliver Tickell, "Live Earth's limits" (6 July 2007)

Mike Hulme, "Climate change: from issue to magnifier" (19 October 2007)

David Shearman, "Democracy and climate change: a story of failure" (7 November 2007)

Alejandro Litovsky, "The accountability challenge for climate diplomacy" (30 November 2007)

Camilla Toulmin, "Bali: no time to lose" (30 November 2007)

Tom Burke, "The world and climate change: all together now" (7 December 2007)

The grey outlook

There are some "givens" in the situation. Despite advances in modern medicine, "nature" could solve some of our problems; although it would be impracticable to attempt by acceptable means a substantial absolute reduction in the human population - other than over the very long term. It is politically implausible to persuade the "haves" to reduce what they regard as their deserved material standard of living and it is immoral to ask the "have nots" to demand less. The most immediate threat is, probably, global warming and its consequences. These elements limit the options, but a sane approach could be to invest in establishing how to secure some control of the rate of increase in average global temperatures and, most importantly, how to turn that increase to advantage.

That approach would lead to other, supporting, investment needs. In no particular order some of these would be:

* investment to reduce the rate of population increase by improving, in the short term, basic living standards and making women equal-particularly in education.

* investment to develop, as a matter of urgency, new technologies to increase the efficiency with which we use the planet's resources, to expand those resources and to devise alternative resources.

* investment to educate both the "haves" and "have nots" in how to use attained and sort for standards of living in a sustainable way.

* investment to persuade - by providing them with alternatives - those "have nots" who are presently trying to improve their lot by doing environmentally "bad" things to desist from doing so.

Investment is financed by accumulated wealth and is made by those with an incentive to do so. Whilst the wealth presently accumulated in the "old" world and the "emerging" world could go some way towards financing the investments listed above (and would in turn add its yield to the global wealth pot) it is difficult to see why those who own that wealth would be likely to do much more than they are doing already. Apart from the investment in new technology - which could provide those who make the investment with handsome returns - much of the rest of what needs to be done looks like the "haves" giving a substantial part of their portion to the "have nots" in order "to save the planet". Sadly, history tells us that this is hardly likely to happen to a sufficient extent or in sufficient time.

Whilst present forecasts are, unavoidably, largely conjectural, it is prudent to assume that global warming (particularly the associated rise in sea levels) is very likely to cause in some parts of the planet disruptive and costly problems both economically and in terms of human misery - associated mainly with mass migration.

The silver lining

But there is also the possibility of some significant gains. Vast tracts of presently unusable land in the northern hemisphere could become habitable and productive. Some commentators say that the Saharan and Indian deserts could revert to savannah. The larger volume of warmer sea water could add to the planet's store of renewable energy. All this, and much more, is speculative and the possibilities change at short notice as scientific assessment improves but it needs to be included in our thinking. It opens the possibility of increased wealth generation in the medium and longer terms. Wealth that would be needed to finance the solutions to the problems of those who will suffer and to meet the unsatisfied investment needs described above.

In whose hands will this additional wealth accumulate and why should they use it in this way? A look at a map tells us that little is likely to accumulate in the hands of the presently dominant "western powers". This will add to the incentive to maintain technological influence (and financial gain) by investment in their science base and to take the role of example-setting whilst pressing for internationally agreed discipline. Increasingly they will present the view that human survival is linked to recognition that our aspirations should extend beyond "goods and children". Prisoners of their own histories, they will find it extremely difficult to persuade many of that view or that it is they who should advance it.

Self-interest, possibly enlightened self-interest (that is the optimistic view), might induce those nations who will have the wealth to extend and consolidate their economic and political power-base by an extensive programme of aid and investment in the infrastructure of the less fortunate. Driven by a wish for influence, it may be starting already and, seen from the viewpoint of humankind, it may be a very good thing.

Environmental change is a large, growing and menacing cloud that may have a silver lining. With or without that lining, what is happening in the environment is not a separate issue. It has strong geopolitical implications with revolutionary potential. That is a very hot potato and, as the old order changeth, is one that national politicians are disinclined to hold, let alone talk about in public. Some prefer to emphasise the problems and the urgent need to work together. Others are more content to await events. It is not difficult to see why. In the meantime the broomsticks are hard at work. And we make more of them by the day.