ASP Summer Colloquium on Uncertainty in Climate Change Research: An Integrated Approach Impacts and Uncertainty Hayley J. Fowler, Newcastle University, UK NCAR, Boulder, CO July 21 - August 6, 2014

Who am I? Geographer – Cambridge University Water Resource Systems Engineering and Civil Engineering (MSc/PhD) Professor of Climate Change Impacts Climate change impacts on water resources→ downscaling for extremes →impacts modelling needed interdisciplinary approach Interested in practical applications and solutions to societal issues/problems related to climate change and particularly extremes Climber, biker, lover of mountains, mum to two small boys, Evan and Calum

That was then… Tocllaraju (6032m) 10:30am 3rd Aug 2006

This is now… Eskdale, Lake District Easter Monday, 2014

US Drought Monitor

Downstream effects on Agriculture Economy Human Health Mitigation

What do we know? WGII AR5 Figure SPM.2

What about the future? Schwalm et al, 2012, Nature Geoscience

Global Mean Annual Temperature Change Relative to 1980-1999 What can we expect? 1ºC 2ºC 3ºC 4ºC IPCC AR4, WGII, Table 20.8 All these contributions are highly valuable stepping stones, but none of them was based on a systemic comparison strategy guided by a unique modeling protocol and a common data pool, as is best practice in the climate modeling and Integrated Assessment Modeling communities, respectively. Furthermore, none of the former analyses aspired to explore the impact cascades arising from cross-sectoral and transregional dynamics. Global Mean Annual Temperature Change Relative to 1980-1999

The Uncertainty Cascade or Pyramid Wilby and Dessai (2010) IPCC AR4 WG2 2007 (modified after Jones, 2000, and "cascading pyramid of uncertainties" in Schneider, 1983) not all layers of the pyramid are equally important, as the Wilby & Dessai illustration might suggest. The relative importance will depend on timescale, region, impact, relevant climate variables and other potential factors. For some impacts, such as health-related heat stress, the uncertainty might actually reduce when considering multiple variables. The next figure attempts to visualise the cascade of uncertainty in projections of global mean surface temperature using the CMIP5 simulations. Each colour represents a different future emissions pathway (the Representative Concentration Pathways, RCPs) (top layer), with each model producing a different response to the same forcing (middle layer). The lowest layer of the pyramid illustrates the role of internal climate variability. This is seen as additional uncertainty for those models which have run multiple realisations of the same forcing pathway, but unfortunately many have not. For the near-term (2016-2035), the relative importance of the RCPs is far smaller than the uncertainty in the model response. However, at the end of the century, the RCP uncertainty tends to dominate more. If each simulation was then used to drive a regional climate model or an impact model then an additional layer could be added to represent the next step in the cascade. This visualisation is potentially complementary to other approaches to describe the relative importance of difference sources of uncertainty in climate projections. Comments on whether this is useful, and suggestions on how it might be improved are very welcome! For example, it might be interesting to look at other climate variables such as precipitation, and at regional projections where variability will be a larger component. Decision-Making (Assessment of needs, decision entry points, institutional constraints, politics etc.)

Toward Decision-making as a Central Focus (Assessment of needs, decision entry points, institutional constraints, politics etc.) Mitigation Adaptation

Climate Change Adaptation Requires clear understanding of the underlying science and methods of assessing impacts - through entire chain from climate scientists to engineers to decision-makers Requires appreciation of both the physical mechanisms as well as the human influence on those strategies (e.g. population rise, land use changes, economics, etc.) and the decision making process itself

Impact Studies Impact studies enable us to produce information for adaptation planning and decision making Climate models produce huge amounts of data but identifying robust and reliable information is a non-trivial task Numerous methodologies for assessing the potential impacts of climate change in various areas have been developed and reported

Climatic impact assessment in the CO2 context — An editorial “One of the principal developing areas of interdisciplinary research is climate impact assessment in general and its CO2 context in particular” Climatic Change Volume 3, Number 4 (1981), 345-346, DOI: 10.1007/BF00139742 Climatic impact assessment in the CO2 context — An editorial H. Stephen Schneider Multidisciplinary research is needed: “research strategy and topics through which…social science disciplines might help define potential responses to the CO2 problem”

History of impact studies Started early 1980s Concentration on agricultural and hydrological impacts, then ecological Focus has gradually shifted to include additional impacts: human health, energy, infrastructure systems – and timescales and spatial scales have become shorter and smaller

Uncertainties in impact studies Multi-model and perturbed-physics ensembles and probabilistic projections (pdfs) Starting to see assessments of uncertainties in impacts models – first steps ISI-MIP and AGMIP Still ad-hoc – structures of models dissimilar, indeed many impacts models not truly physically based (conceptual models) most of the uncertainties addressed in impact studies come from climate modelling still

Goderniaux et al. 2011. Water Resources Research, 47, W12516,

My goals for the workshop To help to educate the next generation in interdisciplinary thinking and integrated approaches to climate change uncertainty To explore some of the big questions in climate change uncertainty – sparking new ideas Helping to move towards climate resilient futures