By Reinhard Mechler, IIASA Risk, Policy, and Vulnerability Program

On March 25, member countries of the Intergovernmental Panel on Climate Change (IPCC) started discussing the key findings of the second volume of the Fifth Assessment Report (AR5) in Yokohama, Japan. The report focuses on climate-related impacts, risks and adaptation. Once approved by the 150+ governments present, together with IPCC’s other two parts of the report on physical climate science and mitigating greenhouse gases, it will constitute the scientific backbone for informing national and international climate policy over the coming years.

Flooded marketplace in Jakarta. Credit: Charles Wiriawan/Flickr (Creative Commons License)

Flooded marketplace in Jakarta. Credit: Charles Wiriawan/Flickr (Creative Commons License)

A key aspect in climate adaptation is dealing with extreme events including natural disasters. It has become clear that extreme event risk constitutes a large part of the adaptation problem, particularly for developing countries and communities.

Despite this growing awareness, the international adaptation policy process is moving forward only slowly. Specifically, there is need for concrete advice for the Loss and Damage Mechanism, the main vehicle under the Climate Convention for dealing with climate-related impacts, which was agreed in Warsaw at the last Conference of the Parties in late 2013

In our commentary, published today in Nature Climate Change with colleagues from LSE, IVM and Deltares, we suggest that better understanding climate-related disaster risk and risk management can inform effective action on climate adaptation and point a way forward for policy and practice.

A key to moving forward is an actionable concept of risk. This involves identifying efficient and acceptable interventions based on recurrency of hazards—a concept known as risk layering. For example, for flood risk, this could mean identifying physical flood protection to deal with more frequent events, considering risk financing for infrequent disasters as well as relying on public and international compensation for extreme catastrophes. Risk layering overall points towards considering risk comprehensively as determined by climatic and non-climatic factors as well as considering portfolios of options that manage risks today and in the future.

The concept of risk layering underlies many areas of risk policy and management in agriculture, finance and insurance. It has been applied for disaster risks, mostly for insurance options, but not informed thinking on comprehensive risk management portfolios. Such broad understanding of risk management can also be helpful in identifying risks that are  beyond adaptation–meriting international support, such as from the Green Climate Fund.

Climate risk management has now moved beyond theory. As one example, the megacity of Jakarta currently is setting up a multi-billion dollar program to manage increasing risk from sea level rise with large levees. This effort is integrated with a concern for managing flood risk and land subsidence, which are shaped by non-climatic factors, such as unplanned urbanization. The effort, therefore, involves options to implement acceptable building and zoning regulations for reducing exposure and vulnerability of houses and infrastructure to flooding.

Many policy-and implementation-specific questions remain. Over the coming months, IIASA researchers and our network will take the agenda on climate risk management forward with a focus on informing policy as well as providing actionable information on the ground.


Reinhard Mechler, Laurens M. Bouwer, Joanne Linnerooth-Bayer, Stefan Hochrainer-Stigler, Jeroen C. J. H. Aerts, Swenja Surminski & Keith Williges. 2014.  Managing unnatural disaster risk from climate extremes. Nature Climate Change. March 26, 2014.

Note: This article gives the views of the author, and not the position of the Nexus blog, nor of the International Institute for Applied Systems Analysis.

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