# **Box n°1: The concept of "maladaptation"**

Measures designed to adapt to the effects of climate change can lead to results that are not consistent with expectations, and "maladaptation risks" should not be underestimated. Maladaptation is defined by the IPCC (the Intergovernmental Panel on Climate Change) as "a change in natural or human systems that leads to an increase rather than a decrease in vulnerability." A maladaptation situation may arise, for example, after a calibration error, i.e., a poor calibration of adaptation measures following an inaccurate prognosis of the nature or extent of future changes or an inadequate response to this prognosis. It may also occur when an adaptation measure leads to the transfer of the vulnerability of one system to another, or one period to another (a measure may be positive for one period and then negative for another, or vice versa).

A distinction must be made between two sources of maladaptation. First, a maladaptation situation _ex post_ can result in entirely appropriate decisions based on information available _ex ante_ . As a result of the uncertainty of the impacts of climate change, the analysis _ex ante_ often only makes it possible to limit the range of adaptation choices possible without limiting it to a specific choice. The choice of the measure to be taken among the set of measures compatible with the information available _ex ante_ on climate change will then be a sort of wager on the part of society (see Section 5). For example, it may appear desirable today to better regulate new construction in low coastal zones. However, if we realize in 2050 that the most optimistic scenario on the rise in sea levels was the right one, this adaptation measure could then appear to be inadequate, even if it is (and remains) desirable today. This type of maladaptation cannot be avoided and can only be regretted _ex post_ if all of the information available was not used _ex ante_ .

On the other hand, a maladaptation situation can also arise from a "poor choice" _ex ante_ , i.e., inadequate consideration of the information available. This is the case, for example, if adaptation measures are established in view of a unique climate scenario, without including uncertainty, or even if advanced signs of local climate change were not detected early enough by stakeholders. This type of maladaptation can lead to regrets _ex post_ since all of the information available was not used to its best advantage _ex ante_ . This type of situation could be avoided if the methodologies for the development of adaptation strategies are well designed and satisfactorily implemented.

Reducing the risk of maladaptation is possible, in particular, by giving priority (i) to "norisk" strategies that reduce the vulnerability of climate change while both reaping immediate cobenefits and maintaining a degree of efficiency independently of which climate change scenario reveals correct; or (ii) to "flexible" or "reversible" strategies that can be easily modified as new information becomes available.

**Several studies** (see Agrawala and Fankhauser, 2008, for a review) **attempt to assess the cost of adaptation measures** , particularly in the infrastructure sector.  They are based on two distinct methodologies: (1) "top-down" approaches, based on sums invested every year in sectors sensitive to climate conditions, and that assume that climate change will lead to additional costs (on the order of 10%) on these investments, and (2) "bottom-up" approaches that attempt to identify and assess the investments necessary in each of the sectors concerned (protection of coasts, water, agriculture, etc.).

"Top-down" estimates of the Word Bank (2006) and the United Nations Development Program (UNDP, 2007) assess adaptation costs at between 9 and 109 billon dollars per year for developing countries. The United Nations Framework Convention on Climate Change (UNFCCC, 2007) proposes an assessment of 49 to 171 billion dollars per year for all countries.

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