Data and code used in the article Expert elicitation of state shifts and divergent sensitivities to climate warming across northern ecosystems

Émilie Saulnier-Talbot1,2+*, Éliane Duchesne3+, Dermot Antoniades2, Dominique Arseneault3, Christine Barnard4, Dominique Berteaux3, Najat Bhiry2, Frédéric Bouchard5, Stéphane Boudreau1, Kevin Cazelles6, Jérôme Comte7, Madeleine-Zoé Corbeil-Robitaille3, Steeve D. Côté1, Raoul-Marie Couture8, Guillaume de Lafontaine3, Florent Domine8, Dominique Fauteux9, Daniel Fortier10, Michelle Garneau11, Gilles Gauthier1, Dominique Gravel12, Isabelle Laurion7, Martin Lavoie2, Nicolas Lecomte13, Pierre Legagneux1, Esther Lévesque14, Marie-José Naud15, Michel Paquette16, Serge Payette1, Reinhard Pienitz2, Milla Rautio17, Alexandre Roy14, Alain Royer5, Martin Simard2, Warwick F. Vincent1, Joël Bêty3+* 

1.     Département de biologie, Université Laval, Québec, Canada 
2.     Département de géographie, Université Laval, Québec, Canada 
3.     Département de biologie, chimie et géographie, Université du Québec à Rimouski, Canada 
4.     ArcticNet, Université Laval, Québec, Canada 
5.     Département de géomatique appliquée, Université de Sherbrooke, Canada 
6.     Omnimed, Sherbrooke, Québec, Canada 
7.     Institut national de la recherche scientifique, Centre Eau Terre Environnement, Québec, Canada 
8.     Département de chimie, Université Laval, Québec, Canada 
9.     Canadian Museum of Nature, Ottawa, Canada 
10.     Département de géographie, Université de Montréal, Canada 
11.     Département de géographie, Université du Québec à Montréal, Canada 
12.     Département de biologie, Université de Sherbrooke, Canada 
13.     Département de biologie, Université de Moncton, Canada 
14.     Département des sciences de l’environnement, Université du Québec à Trois-Rivières, Canada 
15.     VRRCI, Université Laval, Québec, Canada 
16.     Ecofish Research Ltd, Squamish, Canada 
17.     Département des sciences fondamentales, Université du Québec à Chicoutimi, Canada 

All authors are current or former members of the Centre d’études nordiques (CEN Centre for northern studies). +These authors contributed equally to the work; *Authors for correspondence (emilie.saulnier-talbot@bio.ulaval.ca; Joel_Bety@uqar.ca) 

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The data is based on a structured expert elicitation of expert judgment that quantified the relative sensitivity of the interacting components of northern ecosystems across a broad latitudinal gradient. We assessed where and at what rate state shifts of ecosystem components are most likely to occur under warmer conditions along a ~100 km-wide, 3,700 km latitudinal transect that extends from the polar desert of northern Ellesmere and Ward Hunt (83°04’N), the northernmost islands of the Canadian Arctic Archipelago to Matagami (49°45’N), located in the boreal forest biome of the James Bay region.

We used structured expert elicitation inspired by the Delphi technique in which we combined multidisciplinary workshops with several rounds of expert assessments to ensure that all experts had the same interpretation of the questions and fully understood the aim of the project. Our team is composed of 31 experts covering a wide range of disciplines (geomorphology, hydrology, nivology, limnology, plant and animal ecology and plant paleoecology) and carrying out research across the entire study region. Experts were separated into 6 groups (one per component, 2 to 8 experts per group). Facilitators then addressed a series of questions to each group. Facilitators also provided the following guidelines during the elicitation process: contrasting states and state changes had to be defined at the landscape scale (i.e. 30 km x 30 km, except for vertebrates at 100 km x 100 km), state definitions had to be based on measurable characteristics with marked differences between states, and experts had to clearly describe the conditions for a state change as well as for the definition of a southern limit. Experts first identified contrasting states currently found along the transect.

For each ecosystem component, we present:

1. the southernmost location (± 2.5 latitudinal degrees) of all contrasting states along the latitudinal transect, and
2. the relative sensitivity of an ecosystem component at each critical threshold given by the by time necessary for a component located at the southern limit of its current state to shift to another existing contrasting state under a hypothetical warming scenario (3 categories of response time, in years: high sensitivity = 1-10, moderate sensitivity = 10-100, low sensitivity = >100).

These data can be foud in the Response_time.R file.