The thirteenth United Nations Climate Change conference in Bali on 3-14 December 2007 will conclude a year when climate change has moved towards the top of the international political agenda. A series of reports, meetings and plans since the publication of the Stern review in November 2006 (as well as the award of the Nobel peace prize to Al Gore and the Intergovernmental Panel on Climate Change [IPCC] in October 2007) has kept the issue at the forefront of public discussion. But perhaps even more important in sustaining momentum has been clear evidence from around the world of the environmental impact of climate change itself, and the urgency of taking steps to address it.

Paul Rogers is professor of peace studies at Bradford University, northern England. He has been writing a weekly column on global security on openDemocracy since 26 September 2001

The gap between evidence and policy still remains wide, however. There is a long way to go to implant the sense among political leaders of just how important and shaping the challenge of climate change is for human society in the 21st century. It might be worth, then, summarising the broad understandings of climate change's further likely consequences in the coming decades, so that the responsibility facing the IPCC and the world's governments and international agencies can be put in context.

The big heat

In assessing how current climate-change trends will develop, three aspects are especially worthy of note (see "Climate change: threat and promise", 2 November 2006).

First, there is the risk that positive feedback systems will speed up the whole process. A vivid example is the melting of Arctic sea-ice; this leaves darker ocean surfaces to absorb more solar radiation, thus speeding up the melting process. This process could in turn be exceeded by another feedback mechanism: the progressive melting of the Arctic permafrost, which would release huge amounts of methane (a particularly potent climate-change gas) from rotting vegetation. This would further increase temperatures, melting more permafrost and releasing even more methane.

Second, the tropical and sub-tropical regions of the world could be far more severely affected than has previously been thought. Until the mid-1990s, most climate-change models predicted that the main effects would be felt in temperate latitudes whose relatively wealthy societies might be able to cope best. The more sophisticated models that came later have suggested otherwise; they predict that the most heavily populated and poorest regions of the world likely to experience more severe storms, inundation of low-lying coastal areas and, most important of all, a progressive drying out of the land masses as rainfall distribution tends to move from the tropics to the polar regions and from the land to the oceans.

Since these massive changes would affect poorer societies that were hugely dependent on local food production, the consequences in terms of malnutrition, starvation, migratory pressures and social disruption could be catastrophic.

Third, the fact that the official estimates of climate change are necessarily consensus documents - agreed among thousands of scientists and a hundred-plus national delegations - is both a striking indicator of international cooperation and a problem. It is a problem because inevitably, the process of achieving such consensus is enveloped by a persistent air of caution. This is made worse by the need to study and agree the often voluminous data arising from the very welcome increase in research into climate change. The end result was that the most recent research is often not be incorporated into the overall conclusions of the IPCC.

The reality is worse

The IPCC's publication of its new "synthesis report" on 17 November 2007 is an effort to collate the relevant current data, as a prelude to the new round of international negotiations on the control of carbon emissions which the Bali gathering will inaugurate. The report's opening is a stark illustration of the immediacy of the problem: it provides evidence that eleven of the last twelve years are among the twelve warmest years worldwide since accurate instrumental measurements started over 150 years ago.

The report also reveals that the IPCC has repeatedly had to revise its estimates of the impact of climate change upwards, a clear indication of the amount of new evidence tending in the same direction. At the same time, many leading climate scientists argue that the synthesis report does not go far enough; that it still has the limitations of a consensus document that avoids saying how dangerous current global-warming tendencies are (see Elisabeth Rosenthal & James Kanter, "Alarming UN report on climate change too rosy, many say", International Herald Tribune, 18 November 2007).

In addition to his weekly openDemocracy column, Paul Rogers writes an international security monthly briefing for the Oxford Research Group; for details, click here

Paul Rogers's latest book is Global Security and the War on Terror: Elite Power and the Illusion of Control (Routledge, July 2007). This is a collection of papers and essays written over the last twenty years, with two new essays on the current global predicament

This view is condensed by Hans Verolme, the director of the WWF global climate-change programme: "The IPPC is a five-year process, and the IPPC is struggling to keep up with the data - we are all being updated with new evidence and new science, and the new science is saying 'You thought it was bad? No, it's worse'".

A formulation of this kind might be expected from a campaigning organisation. It is striking, then, that the same perspective is shared by Rajendra Pachauri, who as chair of the IPPC is routinely diplomatic in his pronouncements. At the launch of the synthesis report in Valencia on 17 November he said "If you look at the scientific knowledge things do seem to be getting progressively worse. Maybe before we were in a state of ignorance, but also we've seen much stronger trends in climate change. So you'd better start with the interventions even earlier. Now."

The south's peril

In face of the mounting evidence of accelerating climate change, it is obvious that the Kyoto protocols - however painstakingly negotiated - have proved woefully inadequate in their attempts to control emissions. The reasons lie partly in wider political and economic realities. The Bush administration's decision to withdraw from Kyoto in 2001 did much to undermine the agreement. More fundamentally, the two largest newly industrialising countries - India and China - are making coal-fired power stations the instrument of much of their economic development. The Chinese in particular are becoming more aware of the consequences for their own environment of rapid, polluting, greenhouse-gas-emitting economic growth; but like the Indians, they are caught between the imperative of creating a dynamic economy as a way to meet the expectations of their populations and the responsibility to protect their environment.

A further challenge is becoming more visible in the world's tropical zones, which are facing a severe threat to agricultural productivity in coming decades: in tropical areas of Latin America it is predicted to decline by at least 20% over the next 70 years, across Africa by 30% downturn, and in India itself as much as 40% (see Rick Weiss, "Facing a Threat to Farming and Food Supply", Washington Post, 19 November 2007). Moreover, these are decreases on present production levels; they make no allowance for increased food demand coming from up to 4 billion more people, as well as the likelihood that much land could be used to produce biofuels.

The margin for action

The inescapable reality of climate change is at last being seen for what it is: the greatest contemporary threat to the world community, and most immediately to those in the global south who are least able to cope with its effects. Truly radical action will be required in the very near future - and that means years not decades.

To some degree this is already happening:

* strenuous efforts are being made to research new crop varieties that are more drought- and heat-resistant; some of the world's leading tropical agriculture research centres are now concentrating on this task

* there is increasing recognition of the huge potential to conserve energy across the industrialised countries in the global north

* renewable-energy resources (including wind, wave, tidal and photovoltaic systems) are all available for deployment on a far larger scale than at present; countries such as Denmark and Germany are making progress here.

Against this, there are the fundamental obstacles of political inertia and vested interests, the lack of political will, and the bureaucratic time-wasting that goes into producing multilateral agreements.

What is needed is a combination of strenuous and persistent citizen movements and some clear and unambiguous examples of political leadership. The former is already taking root, aided by unexpected events such as the Nobel peace prize award to the IPPC/Al Gore award, but there is little evidence of the latter.

The British prime minister Gordon Brown made an unexpectedly robust speech on 19 November 2007 that committed Britain to strong, ambitious action on climate change; yet full details of the new policies are not due for eighteen months and even if implemented will be far from sufficient. Furthermore, Brown's own government (surrounded already by a host of political and economic problems, including the loss of huge amounts of electronic data on citizens) is locked into its own contradictory policies: advocating a substantial increase in air traffic through London's Heathrow airport, for example, while failing in its plans to achieve a zero-carbon homes policy by 2016 (see Ashley Seager, "Labour lagging behind in plan for zero-carbon homes", Guardian, 22 November 2007).

When policies and outlooks face both ways at the same time, whether in China or western Europe, it is not simply due to the venality of governments or the powers that influence them. It may be that, even as climate change increasingly impacts on the world's most vulnerable communities, urgently needed radical action to avoid such a disaster is beyond the capacity of current political systems.

Yet there is no alternative. We need to work with what we have got, and much will depend on whether non-governmental groups and the wider civil society can force sufficient change on a decidedly reluctant polity. We will know within five years at most.