The climate adviser’s dilemma

To ensure scientific integrity in climate policy, advisers need to take a step back from politics.
 

Press conference for the launch of an Intergovernmental Panel on Climate Change (IPCC) report. Photograph: Amanda Voisard/UN Photo

There is a shift underway in international climate policy. The top-down approach to mitigating climate change that has guided policy since 1992 is slowly being replaced by a bottom-up model. The focus is no longer on meeting a global climate stabilization target of 2°C, or on establishing a legally binding carbon budget. The negotiations on a global agreement to be concluded in Paris in December will instead focus on voluntary mitigation commitments. It is already clear that the aggregated contributions will be nowhere near adequate to maintain the 2°C target.

This shift in public policy has consequences for the scientific community. Ideally, expert knowledge for policymakers has to meet two conflicting standards at once: it must be scientifically sound and politically viable. If expert advisers want to maintain their close working relationship with countries at the forefront of international climate policy, they will have to provide more pragmatic policy evaluations and recommendations. At the same time, advisers face a growing need to carefully consider the long-term consistency of their recommendations.

The two main camps of researchers providing expert advice on climate policy — natural scientists and economists — are being affected by this shift in rather different ways.

For natural scientists, the situation looks relatively good. The basic concept of anthropogenic climate change is now generally accepted worldwide, despite the persistence of some denial in countries like the US, UK and Australia. For a while now, the central question in the global debate has not been whether climate change is happening, but how, to what extent, and at what rate. This might eventually lead to a depoliticisation of scientific research, which will allow scientific uncertainties to be discussed again in a more dispassionate way.

But how will natural scientists react to the growing political pragmatism? If it becomes increasingly obvious that climate policy is not derived from a global stabilization target, scientists will be forced to choose between two equally inconvenient options. They could vigorously defend their original concept ofplanetary boundaries and global thresholds, which would be met with increasing dissatisfaction by politicians, policymakers, and public funding agencies. Or they could soften their stance on an exact threshold to ‘dangerous climate change’, perhaps by allowing for temporary temperature overshoot or even higher stabilization targets.

The situation is even more complicated for climate economists, whose importance has grown steadily since the IPCC’s Fourth Assessment Report in 2007. By developing models to calculate global emissions scenarios, economists have taken a position at the forefront of the climate debate. Correspondingly, during the work on IPCC’s Fifth Assessment Report, it was Working Group III (Mitigation) where governments’ line-by-line approval of the ‘Summary for Policymakers’ proved most contentious. 

Climate economists are not only entrusted with the authority to say which measures should be taken to reach climate targets with minimized costs, but as global emissions continue to rise, policymakers confer to them the uncomfortable task of saying which international climate objectives are still feasible.

A good example of the dilemma scientific policy advisers are facing is the concept of the emissions budget. The later the global emissions peak is reached, and the higher that peak is, the greater subsequent annual reduction rates will have to be in order to stay within the remaining budget.

But what if policymakers do not comply? Again, advisers face two equally unappealing options. They can either become less policy-relevant or more pragmatic. Economists could stick to rigorous calculations and distance themselves from the policy process by declaring that it is no longer possible to stay within a 2°C compatible carbon budget. But since funding agencies continue to generously reward policy optimism, and since the global climate community still tends to believe that abandoning the 2°C target will lead to a sense of fatalism, climate economists have so far chosen a more pragmatic path.

This has led to a paradoxical situation. With each year of increasing emissions, the assumptions economists make about the transformative capacity of the global economy look more optimistic — and less plausible.

The usual way in which climate economists have managed to get around make-or-break points for the 2°C target is by calculating in significant amounts of ‘negative emissions’ — the removal of greenhouse gases from the atmosphere during the second half of this century. Most models assume this can be achieved using a combination of approaches known as BECCS: bioenergy (which would require 500 million hectares of land – 1.5 times the size of India) plus carbon capture and storage (CCS). This approach, which allows making up for missed emissions reductions at a later stage, underscores climate economists’ political acumen. In national political arenas it is common to factor in the option of debt when developing fiscal budgets. Negative emissions allow us to overshoot the carbon budget by establishing ‘carbon debt’, to be paid back later in the century – at least that is the hope.

Unsurprisingly, policymakers show little inclination to discuss a potentially controversial technology that would require extra land use which equates to almost half of today’s arable land worldwide. Decision makers are delighted to hear that despite 25 years of dramatically increasing emissions the 2°C target is still theoretically within reach. But they ignore the fine print, and the IPCC makes it much too easy for them to do so given the enormous complexity of the issue — even in its summaries for policymakers.

For the past two decades, there has been an increasing discrepancy between climate policy intentions and the reality of rising emissions. While some degree of nonchalance regarding inconsistencies in talk, decisions, and actions is part of everyday life for politicians and diplomats, this is an attitude that has put scientific policy advisers in a difficult position, and one that is creating a sense of growing unease among climate scientists.

Yet the central theme of the climate policy narrative—and the one currently upheld by mainstream scientific advisers — has remained the same: “Time is running out, but we can still make it if we start to act now”. This statement is incompatible with the principle of scientific consistency. When scientific policy advisers fall back on this mantra, they are reaffirming their established working relationship with climate policy pioneers like the EU. But in doing so, they are also effectively glossing over two decades of climate policy inaction.

It is by no means the task of advisers to spread optimism about the future achievements of climate policy. Instead, they should critically analyze the risks and benefits of political efforts and contribute empirically sound – and sometimes unwelcome – perspectives to the climate policy discourse.

For some time now, responsibility for successfully addressing the climate problem has rested in the hands of governments. Valuable scientific knowledge will remain an important factor going forward, but it will by no means be the decisive factor. To start taking effective action, politicians and policymakers already know more than enough.

Oliver Geden (@Oliver_Geden) is head of the EU Division at the German Institute for International and Security Affairs (SWP) in Berlin. This article is based on acommentary in Nature and a recent SWP policy paper.