Question

Which question has been addressed in this step?

Exploring risks: What are the adaptation turning points, or thresholds for sociopolitical objectives?

Why has this question been chosen?

• The turning point occurs when actors decide that existing policy objectives or societal preferences cannot be sustained in the light of changing conditions. Adaptation turning point analysis makes use of impact analysis to bring attention to the potential socio-political thresholds that may be crossed in the future.
• An adaptive turning point communicates the urgency of rethinking actual policies

Which methods have been applied?

1. Stakeholder consultation:
   • Formal policy objectives from the ICPR on salmon restoration were taken (ICPR, 2004; ICPR, 2010) as a basis for indicator and threshold identification. As salmon policies exist on different scales, references are made to policy objectives / standards / administrative arrangements on the scale of Rhine tributaries. Basis for these references are:
     • Four interviews with experts in the Middle and Lower Rhine
     • Results from a Rhine restoration research conducted in 2008-2010 (van Slobbe and de Block, 2011)
     • Literature
2. Impact projection:
   • Water temperature was simulated on daily time step for both historic (1980-1999) and future climate (whole 21st century) using a coupled hydrological-water temperature model forced with biascorrected Global Climate Model output.
   • Daily water temperature simulations were used in combination with critical water temperature limits for salmon to assess changes in the occurrence of exceeded water temperature thresholds for salmon

Why have these methods been selected?

1. Stakeholder consultation:
   • The socio-political threshold is defined as a significant reduction of upstream migrating salmon. As success of reintroduction policies is expressed in numbers of migrating salmon per year.
2. Impact projection:
   • Modelling of Rhine water temperature has only recently started and only first time series are available yet

What results have been obtained?

1. Stakeholder consultation:
   • Actors/policies which may be threatened when biophysical thresholds are crossed have been identified. However, as reintroduction of the salmon depends on activities at different levels (local to international) a sharp definition of a turning point is not possible. The analysis brings attention to who will lose motivation to invest in salmon reintroduction first. Important actors are the local NGO managing nurseries, actors involved in the tributary platform looking at spawning habitat reconstruction, or the council of ministers deciding upon expensive fish passage constructions.
2. Impact projection:
   • Projections of water temperature in the Rhine show a mean number of days per year that daily water temperature exceeds 23°C in the period 2080 - 2099 in the range of 27- 83 days. Transient runs of water temperature models of the Rhine show years with a maximum of ~100 days with water temperatures in excess of 23°C. There is limited knowledge on what number of days with water temperatures in excess of 23°C (or duration of exceeded threshold) will negatively affect the numbers of migrating salmon. Nevertheless, our analysis of adaptation turning points suggests climate change may significantly affect the success of salmon reintroduction and does imply the need to rethink salmon policies or to start thinking about adaptive action.

Reflections on this step

• Impact projection:
  • Uncertainty in model projections is high, but nevertheless a relevant signal is identified. Due to the wide margin of uncertainty and the impossibility to define a threshold in terms of number of days with a daily temperature higher than 23°C it is not possible to define a turning point or a turning period in time.