Talking about future under climate change

On 25 to 27 August 2014, “Third Nordic International Conference on Climate Change Adaptation” took place in Copenhagen. I was asked to join a discussion panel at the end of the conference - with a short opening statement.

From listening to presentations here at the conference I got the impression that the term “future” is not always well defined even though it plays a very important role in thinking about and in planning adaptation. Often people describe the situation in a way as if that would be stationary “today” and then equally stationary “tomorrow”. In this framing the difference between today and tomorrow is only climate; everything else tomorrow is like today. This view is fundamentally flawed because

1. a characteristic of “future” is its instationarity, i.e.,  permanent ongoing change without reaching “constant” conditions. Thus, traditional “stationary” planning tools and numbers, such as the “200 year flood” makes no sense anymore. Indeed, such a term is to express the probability of the present state-which makes sense also in instationary conditions, but it does not imply the forecast that such an event would, in a certain average sense, take place once in the coming 200 years.
2. another characteristic of “future” is that many other things are changing as well-such as societal preferences, conflicts, land-use and technology.

Speaking consistently about possible and plausible futures requires taking these characteristics into account.

As an example let me report about our practice at the Helmholtz Zentrum Geesthacht in exchanging and advising with managers responsible for coastal defense in Northern Germany. This practice is based on two observations

1. Precise or even only probable numbers for traditionally defined key parameters representative for future risks are not available. Only possible and plausible ranges of such parameters can be determined; these ranges are time-dependent, and the uncertainty (the width of the range) increases with time. More research usually does not reduce this uncertainty, but the complexity will be better understood. However, waiting will result in in more independent observations, and will thus reduce the unavoidable uncertainty.
   On the market there are certainly parties, who claim to be able to meet the demand for precise numbers. This service may be useful in getting formal legitimation, but the information will be mostly useless.
2. Coastal defense will see rising sea level in the future, but hardly a significant change in storm activity. The rate of increase is a presently hotly discussed issue. It will take considerable time and new observations in the future to sort out this issue. In the coming 30 years or so the sea level rise will be limited to about 30 cm or less. At a later time the increase may be considerably higher. More than 120 cm at the end of the 21st century are considered unlikely, but surprises of even higher increases cannot be excluded.

Based on these observations we advise managers to think of two time horizons of decisions namely today and in about 20 to 30 years. After discussing with managers we suggest for the coming 20 years is

• Monitoring of changes of regional sea level, and comparison with projections provided earlier by scientists. Together with this monitoring, every five or 10 years an updated assessment of the present sea level rise should take place.
• Modernization of coastal defense to maintain present levels of security as needed - in such a way that the modest increase in the coming 30 years is dealt with and further massive fortifications remain possible for the time afterwards
• Maintaining flexibility for planning in potentially critical areas.
• Development of new technologies (such as improved “overflow”) and risk limiting strategies in combination with other goals.
• Engagement with the public in participation processes: developing and discussing strategies for dealing with the changing risk and adaptation needs and assessing consistency with regional societal preferences and values.

When approaching the second time horizon, in about 20 to 30 years, we must be prepared to be confronted with considerably more demanding challenges in coastal defense. The achieved additional knowledge about the sea level rise, the improved set of possible responses to the increased risk, and the awareness of the public and other stakeholders about options and societal preferences and possible conflicts, will ease the certainly not easy decision process at that time.

In all this it is crucial that it is understood that the decisions needed are fundamentally political, and that adaptation science can provide useful information, which may shed light on technical aspects (in particular concerning efficiency) of the different options.

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