The recent report of Intergovernmental Panel on Climate Change on the aspirational target in the Paris Agreement of limiting global temperature increase to 1.5°C makes three important points:

• Meeting the aspirational 1.5°C target would require us to abandon coal and other fossil fuels in the next 10-12 years—theoretically feasible but in practice quite impossible given the investments already made and planned in the production and use of fossil fuels.
• Staying with the agreed 2°C target would imply significantly higher risks relative to the 1.5°C target including doubling of the number of people affected by water scarcity more tropical crops adversely affected, halving of global fishery catch, higher sea level rise and increased risk of destabilising ice sheets in Antarctica and Greenland.
• We are not on track even for the 2°C goal as the pledges made under the Paris Agreement, which extend only to 2030, would lead to an increase of about 3-4°C by end of century with further warming potential beyond depending on the actions taken beyond 2030.

It is now clear that we will see a temperature increase of 2°C or more and greater climate instability with more deadly heat waves, more heavy rainstorms, more storm surges and more intense and frequent floods and droughts. Each of the five assessment by the IPCC have been more dire and more definite than the previous one. We now know enough to require us to act immediately. The contentious issue is who will do what, when and who will pay for it. 

Managing climate change is a zero-sum game as the total carbon budget available for any given goal for limiting temperature increase is fixed. For a 2°C goal, this would be around 1320 gigatons of CO², which would be exhausted in 30 years at the current rate of emissions. The world community has sought to address this issue of sharing a fixed cake without agreeing on any basis for determining each country's permissible share. The current system of voluntary pledges goes even further and leaves it to the good sense of each country.

The time has come the step beyond this and make climate ethics central to this debate. This is not an unusual demand. We have accepted the centrality of ethics in global negotiations on humanitarian and human rights issues.  We also know that the issues arising from externalities can, in practice, only be resolved on the basis of some principles of fairness and liability. Climate change is a shared risk, a global externality and we need to address it as a single global community and not as a set of fractious national governments.

The foundation for burden sharing has been laid down in the UN Framework Convention on Climate Change's principle of: “common but differentiated responsibilities and respective capabilities” This principle has to be applied to secure equity between generations, between nations and between individuals taking account of differences in culpability, capacity and impact.

Take first the issue of equity between generations. The unborn clearly have no influence on today's decisions. The evidence also clearly shows that the impact on them will be greater than on us. Their capacity to address the problem could be better because of technological advances. But the basic conclusion has to be that, with regard to future generations, all of us now, rich or poor, are culpable and hence have a duty to reduce future risks. In doing so we have to ensure that our mitigation actions (like geo-engineering for instance) do not create new types of risk.

Equity between nations has been at the heart of the global negotiations on climate cooperation.  Since climate change arises because of the accumulation of greenhouse gases in the atmosphere, culpability, as measured by cumulative past emissions, has been advanced by developing countries but rejected by most developed countries as a basis for determining mandatory or voluntary national obligations. Differences in the capacity to act have been accepted but increasingly only for the poorest and least developed countries. There are large differences in national impact and the ethical issue  of how the smaller and poorer countries should be helped and by whom, to adapt to unavoidable climate change,  has received only limited attention in the negotiations so far. 

The differentiation by culpability, capacity, and impact that we seek to apply between nations should also apply to burden sharing between rich and poor individuals within nations.  The differences in impact between the rich and the poor could be particularly acute in tropical countries with a large agrarian population. Health and livelihood impacts may be greater on poor households who cannot protect themselves from higher temperatures and increased extreme events. But burden sharing between individuals will have to be based on current culpability and capacity. as the cumulative culpability inherited by each individual from his ancestors is difficult to define and hard to measure.

A possible negotiaiting approach would be to treat the world as one community and focus on equity between individuals across national boundaries. This can allow us to apportion responsibility on the basis of current culpability and capacity. Culpability for the past could play some role in apportioning responsibility, on the basis of the polluter pays principle, for financing and supporting adaptation measures.

However, such an approach for injecting ethics formally into the global negotiating process will be rejected by the US which has been a spoiler in this process for decades. Nor would it be welcomed by countries like China, whose obligations may rise significantly.

Some civil society groups, of which there are now many, could make a beginning by bringing together a group of large and small countries ready to move beyond self-centred and half-hearted incrementalism. The goal should be to spell out a joint multi-national plan that focuses on justice between individuals, now and in the future, and treating the outcome as the basis for their national commitment.

The time has come to focus as much attention on what each one of us must do as on what others should be doing.