Now the debate has begun on “what after 2015”. The ball for a “post-2015 development agenda” has been fast-tracked by recent developments. Countries agreed, at the recently concluded Rio+20 summit, on working towards new “sustainable development goals” (SDGs). Subsequently, the UN secretary general appointed a 26-member high-level panel to advise him on the post-2015 agenda.

But the world of 2012 is very different from the world of 2000, when the original MDGs were agreed upon. The economic sweepstakes are much higher. Global geopolitics is more complex. No longer can decisions be simply made behind closed doors of the UN Plaza. There are loud calls for a more inclusive, transparent and “bottom-up” process. Given these complexities, the process for arriving at the post-2015 agenda is likely to be protracted, messy and contested.

Here, I focus on one set of goals that are going to be especially challenging—those related to environmental sustainability. The original MDGs had a specific goal on environmental sustainability with four targets and eventually 10 indicators. While not much is known on how these were arrived at in the proverbial smoke-filled rooms of the UN, it is clear that this time round will not be straightforward. As we have seen in climate change negotiations, the environment seems to be the new flashpoint in international negotiations. There are plenty of unknowns and questions which make the post-2015 environment targets particularly difficult to agree upon.

First, what does the cleverly crafted phrase “global goals with contextualized national targets” really mean in the context of the environment? The phrase “common but differentiated responsibilities” has been a favourite of environmental negotiators for decades, but it is not clear how this will evolve, with many developed nations trying to distance themselves from the “differentiated” dimension, arguing for large developing countries taking on more obligations.

Second, how will the agreed targets and indicators be applied in practice? Developing countries worry, for example, that if they commit to quantitative indicators such as carbon emissions, they open themselves to censure and unilateral tariff barriers on the pretext of environmental concerns. In other words, the post-2015 targets could become an excuse for protectionism. The recent controversy surrounding the aviation tax levied by the European Union is an example.

Third, what do targets on the environment dimension mean for the other goals, some of which may involve difficult trade-offs, eg., poverty reduction (through increased consumption by the poor and access to modern energy services, etc). These may impose environmental costs and slow the progress towards the environmental goals—how do we account for these trade-offs?

Fourth, who will pay, and how much, to achieve these targets? In the context of an economic slowdown in developed countries, the appetite to finance actions of developing countries, many of whom are now looked upon as economic “competitors”, is low. What happens to the targets in the absence of adequate finance?

All this means that the negotiations for post-2015 targets on the environment are going to be difficult. So what is the way forward towards a set of post-2015 targets for the environment? Here are some concrete suggestions.

First, build an environment of trust upfront—this can be done, for example, if all nations categorically commit that no unilateral trade barriers or other protectionist penalties will be imposed with respect to the achievement of the post-2015 targets.

Second, focus on the “low-hanging fruit” on which we can get rapid consensus. Targets on access to safe drinking water and basic sanitation, for example, are already agreed upon under the current environmental goals of MDGs. These kind of targets may be amenable to early consensus.

Third, err on the side of practical rather than bold. It is better to start with a small set of modest, non-controversial targets that get accepted, rather than endlessly debate a long list of ambitious ones on which there is no consensus. These targets should come from individual countries themselves with an accountability framework in place so that progress can be verified transparently. There should be an interim review mechanism—say after five years—to reassess and enhance the targets, once we know how we are doing, and in light of newer data and science.

Agreeing on a post-2015 agenda will be challenging. But we must not let the best be the enemy of the good. Through a pragmatic and incremental approach, much can be achieved.