The failure of the 2009 Copenhagen climate conference marked a shift in international climate governance. As the system of agreeing international emissions reductions targets and then negotiating individual country contribution towards that target proved increasingly unworkable, there has been a drive towards a much more bottom-up form of climate governance. In preparation for the Paris summit later this year, countries are submitting Intended Nationally Determined Contributions (INDCs) to the international community, hoping that together, these contributions will add up to limit global warming to two degrees Celsius. These national pledges are—at least in part—backed up by a range of decentralized activities by countries, regions, cities, as well as businesses, civil society and others, who have been taking their own initiatives to address climate change. But what do we know about this bottom-up approach to climate governance and can it work?
In a recent article published in Nature Climate Change, we seek to shed some light on the distribution, the origins and the consequences of these bottom-up approaches to addressing climate change. Past research highlights a proliferating number of initiatives at various levels and in various places. For example, studies have documented a great number of international initiatives, transnational approaches, as well as a significant growth in national legislation to address climate change with 500 laws and policies addressing climate change in 66 countries in 2013, up from only 40 in 1997. We also know that there is a range of motivations for politicians, business leaders and others to engage in mitigation of climate change – some financial, some non-financial incentives. However, while this body of knowledge has accumulated, we know comparatively little about the consequences, or effects, of these bottom-up approaches. A key question is does bottom-up climate governance add up to something significant? And does it deliver? And by which criteria should it be evaluated?
Evaluating the performance of these bottom-up forms of governance raises a range of technical and political challenges. The international climate regime has struggled to consistently evaluate performance, such that much depends on self-reporting by states and other actors. In these compliance exercises, the focus has often been on whole countries and sometimes whether certain country characteristics, such as institutions or democratic governance drive performance, but often not individual policies. For instance, while we know that the European Union has reduced its greenhouse gas emissions, much less is known about the causal factors behind this – was it simply a renewal of old industries (e.g., after German reunification or the switch from coal to gas in the UK), the economic crisis, carbon leakage to countries not bound by emission reductions or policies that created incentives for renewable energy, legislation for energy efficiency, emissions trading, or a combination of all these factors? The ever-increasing number of bottom-up approaches, with some reaching beyond national borders, exacerbates these evaluation challenges.
There is very little comparative data on individual climate policies and initiatives, particularly on a range of intended or unintended (and often important) side effects beyond greenhouse gas emission reductions. In particular, while the United Nations Framework Convention on Climate Change (UNFCCC) focuses on ex-ante predictions of actual policy effects, there is currently a dearth of information on ex-post (i.e., retrospective) evaluations of policy effects. Technical difficulties and low resources may partly explain this lack of knowledge. But policy-makers may lack incentives to provide such information, because it could potentially highlight the ineffectiveness of ‘their’ policies.
We know even less about the effects of transnational approaches, where an energetic debate is underway regarding the criteria to use for evaluation. Evaluation research has taught us that complex activities need to be evaluated using multiple criteria. ‘Hard outcomes’ such as greenhouse gas emission reductions are the ultimate proof, but they may not materialize immediately, and ‘soft’ outcomes such as building trust and learning may be necessary to create conditions for significant reductions of emissions. But to learn more we need to investigate effects from multiple perspectives and with multiple tools, including an examination of some very simple features, for example whether new initiatives incorporate monitoring and evaluation that support learning from all the new efforts. Another important question to ask is whether these approaches last long enough to have enduring effects.
Taken together, we conclude that much remains to be learned on the effectiveness of bottom-up climate governance. The jury is still out on whether it can fill the gaps left by the Kyoto-based international climate regime. To make robust conclusions possible we need a concerted research effort on the merits of these new approaches to climate governance. Policy-makers would be well advised to support new approaches, but not to abandon the more traditional international negotiation processes before we know more about what actually can be achieved through bottom-up climate governance.
 Jordan, A.J.; Huitema, D.; Hildén, M.; van Asselt,H.; Rayner, T.J.; Schoenefeld, J.J.; Tosun, J.; Forster, J.; Boasson, E.L. Emergence of polycentric climate governance and its future prospects Nature Climate Change. Available at http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2725.html
 Bulkeley, H. (2014). Transnational climate change governance. New York: Cambridge University Press.
 Hildén, M., Jordan, A., & Rayner, T. (2014). Climate policy innovation: developing an evaluation perspective. Environmental Politics, 23(5), 884-905.
 Mickwitz, P. (2013). Policy evaluation. In A. Jordan, & C. Adelle (Eds.), Environmental policy in the EU: Actors, institutions and processes (pp. 267-286). London; New York: Routledge.