Strategic Planning For Future Water Resources Under Climate Change:

Rowan Fealy Department of Geography

Maynooth University

Water: The Greatest Global Challenge, DCU Innovation Campus 28 November, 2014

Use of climate models in the decision making process

Use of climate models in the decision making process

• Context

• Model Uncertainty

• Challenges for Decision making − Traditional ‘Predict and Provide’ Approach in Impact

Assessment

• Alternative Approaches

‘There is now a scientific consensus that global warming is happening, that it is directly related to man-made greenhouse gas emissions, and that we have little time remaining to stabilise and reduce these emissions if we are to avoid devastating impacts on our planet.’

National Climate Change Strategy, 2007-2012

The need to incorporate information about future climate in our decision making process is apparent, however, the practice of doing so, is somewhat

less clear

‘…identified the failure of climate change adaptation and rising greenhouse gas emissions as among those global risks considered to be the most likely to materialize within a decade’

World Economic Forum (WEF) Global Risks Report, 2013

Projections of Future Changes in Climate

White areas are where less than 66% of the models agree in the sign of the change and stippled areas are where more than 90% of the models agree in the sign of the change.

Winter Summer

Changes in precipitation (%) for the period 2090-2099, relative to 1980-1999. Values are multi-model averages based on the SRES A1B scenario.

(Source: IPCC, 2007)

“There has been some improvement in the simulation of continental-scale patterns of precipitation since the AR4. At regional scales, precipitation is not simulated as well, and the assessment is hampered by observational uncertainties.”

(IPCC, 2013:11)

Projections of Future Changes in Climate

Projected changes in the mean ensemble precipitation (%) from the ENSEMBLES regional climate modelling project for 2016–2035, relative to 1986–2005, for DJF (left) and JJA (right) derived from 10 GCM-RCM combinations for the SRES A1B scenario. The stippling indicates where 80% of the models agree in the sign of the change.

(IPCC, 2013 after Rajczak et al., 2013)

Winter % Change Summer % Change

Regional Precipitation Change

Relative change in 100-year return level of river discharge between scenario (2071–2100) and control period (1961–1990) for various climate models.

‘Predict and Provide’ Approach

(Feyen et al., 2011)

Relative change in expected annual damages (EAD) (averaged over NUTS level) between scenario (2071–2100) and control period (1961–1990) for various climate models.

‘Predict and Provide’ Approach

(Feyen et al., 2011)

“GCM scenarios produce such widely varying results that it is simply impossible to develop a tailored, cost-effective adaptation strategy when it is not known whether there will be more or less runoff in a particular river basin in the future.”

Stakhiv (1998)

“The information currently available from GCMs is simply inadequate for most operational and design aspects of water sector decisions, and is not expected to be useful for at least another decade.”

Stakhiv (2010)

Prof. Eugene Stakhiv (water resources systems engineer), Corps of Engineers, Institute for Water Resources (IWR) and Technical Director, International Center for Integrated Water Resources Management (UNESCO)

“GCM scenarios produce such widely varying results that it is simply impossible to develop a tailored, cost-effective adaptation strategy when it is not known whether there will be more or less runoff in a particular river basin in the future.”

Stakhiv (1998)

“The information currently available from GCMs is simply inadequate for most operational and design aspects of water sector decisions, and is not expected to be useful for at least another decade.”

Stakhiv (2010)

Prof. Eugene Stakhiv (water resources systems engineer), Corps of Engineers, Institute for Water Resources (IWR) and Technical Director, International Center for Integrated Water Resources Management (UNESCO)

Progressing from emissions to climate response contributes to the overall uncertainty of a climate model projection

(IPCC, 2007)

Even if we could develop a ‘perfect’ climate model, future projections would continue to remain highly uncertain (Wilby, 2010)

‘Predict and Provide’ Approach

In spite of these recognised limitations, contemporary approaches to adaptation are developed on the premise that climate models produce ‘reliable’, ‘precise’ and ‘accurate’ predictions of future climate.

(Source: Shine and Desmond, 2011)

Global Climate Model

Hydrological Model (ie. stream flow; Q5,Q95)

Regional Climate Model (ie. catchment precipitation)

Changes in median, Q05,Q95

Vulnerability & Risk Assessment

Future Emissions

Human Actions

Incorporation of Probabilities

Seasonal mean change in precipitation (%) for Cork Airport (River Blackwater), Mullingar (River Boyne), Belmullet (River Moy), Claremorries (River Suck) and the grid box representing Ireland from the 17 GCMs employed by Fealy (2010) for the period 2070-2099, relative to 1961-1990.

(Table source: Bastola et al., 2012)

The 90% CI of monthly streamflow (2070–2099) simulated using the behavioural parameters of four hydrological models forced with daily probabilistic scenarios derived using regionalised station information (SDprob) and direct output from 17 GCMs (CF).

Implications for Hydrology

(Source: Bastola et al., 2012)

(Source: http://unfccc.int/adaptation/nairobi_work_programme/knowledge_resources_and_publications/items/4555.php)

‘Lock-in’ adaptation strategies may increase vulnerability to climate change rather than decrease it.

Local Authority Unaccounted for Water (UFW) 2010

Develop an approach which is low regret, reversible, priorities ‘soft’ strategies, iterative and flexible.

(Wilby, 2012, After Dessai and Hulme, 2007)

Alternative Approaches

Alternative approaches, which do not rely on having accurate predictions, allow for climate model information to be incorporated into the decision making framework.

Decision making and deep uncertainty

Prediction-based policy analysis requires that we ask

What is likely to happen in the future?

However, the more appropriate question should be

What action should we take, given that we cannot predict the future?

(Source: Lempert and Schlesinger, 2000)

A robust adaptation strategy is one that should perform well over a wide range of possible, uncertain, future scenarios. It is one that minimises regret rather than

seeking an optimal solution, which may not exist.