Sylvain BIGOT 1, Guillaume FORTIN 2, Florian RAYMOND 1 2, Sandra ROME 1 and Dominique DUMAS 3

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1 Recent ( ) and future ( ) major temperature variations in middle mountain areas: comparison between Vercors (Rhône-Alpes, France) and Gaspe Peninsula (Quebec, Canada) Sylvain BIGOT 1, Guillaume FORTIN 2, Florian RAYMOND 1 2, Sandra ROME 1 and Dominique DUMAS 3 1 Université Grenoble Alpes, Laboratoire d étude des Transferts en Hydrologie et Environnement (LTHE), France 2 Université de Moncton, Département d'histoire et de géographie, Canada 3 Université Grenoble Alpes, Institut de Géographie Alpine, France August 11-15, 2013 Session 07 : Climatology: Time-series analysis, variability and trends

Context and collaborations A French-Canadian scientific collaboration on middle mountain climate variability, with different research objectives: measurement and

The Zone Atelier Alpes: a research structure of CNRS designed to foster understanding of the relations between society and its environment.

2 Context and collaborations A French-Canadian scientific collaboration on middle mountain climate variability, with different research objectives: measurement and instrumentation, physical geography, nivology, ecology, phenology. The Zone Atelier Alpes: a research structure of CNRS designed to foster understanding of the relations between society and its environment. Integrated into Alter-Net, a European network of excellence, and into LTER, an international network of sites dedicated to long-term biodiversity and ecosystem research. Regional issues related to climate change: biodiversity and landscape conservation, forestry and agricultural activities, tourism and mountain resorts

3 Objectives 3 principal questions: Determine the principal modes of interannual temperature variability for two mountain regions located on both sides of the Atlantic Ocean (Gaspe and Vercors). Identify their main similarities and differences: intensity variations, synchronicity, regional patterns. Indicate the main regionally trends of temperature planned in the medium term (by 2050). a scientific goal in the longer term: determine future changes of the main ocean-atmospheric forcings in the North Atlantic sector.

The westernmost part of the French Alps (in the Northern

4 The 2 study areas The Vercors A range of plateaux and mid-mountains in the Departments of Isère and Drôme. The westernmost part of the French Alps (in the Northern Prealps) A gateway to the south of France (and Mediterranean influences)

5 The 2 study areas The Vercors A North/South topographic profil of Vercors (from Google Earth) Hauts plateaux A subalpine ecosystem GRENOBLE Differents views from hauts plateaux

The 2 study areas The Vercors The Réserve Naturelle des Hauts Plateaux du Vercors : More than 20 years of field research (plant ecology, hydroclimatology, meteorology, lanscape ecology,

6 The 2 study areas The Vercors The Réserve Naturelle des Hauts Plateaux du Vercors : More than 20 years of field research (plant ecology, hydroclimatology, meteorology, lanscape ecology, geomorphology, remote sensing...). Protected area established in 1985 About 170 km² the largest nature reserve in metropolitan France Altitude range : m A natural laboratory to study environmental changes and climate forcings, with many phases of instrumentation since 2005.

7 The 2 study areas The Gaspe Peninsula A North/South topographic profil (from Google Earth) About km² Altitude range : m A complex topoclimatic environment

8 The 2 study areas The Gaspe Peninsula View of the Chic-Chocs Mountains. Mountainous landscape essentially covered by forest View from Pic de l Aube. View from Mount Ernest Laforce. Mapped from CIRCA data (2000)

Climate data Gridded observation data sets The NCEP/NCAR Reanalysis monthly means (1948-2012) (National Centers for Environmental Prediction/National Center for Atmospheric Research) The NCEP/DOE

9 Climate data Gridded observation data sets The NCEP/NCAR Reanalysis monthly means ( ) (National Centers for Environmental Prediction/National Center for Atmospheric Research) The NCEP/DOE AMIP-II Reanalysis monthly means ( ) (Department of Energy - Atmospheric Model Intercomparison) Selection of the near-surface air temperature (at 995 hpa level) For example, January average ( ) T (C ) Gaspe Vercors Determination of regional climate indices; Analysis of seasonal and interannual variability.

Name Beginning Altitude (m) % no data Amqui 1957 166 5,1 Cap Madeleine 1882 2 6,5 Gaspé

10 Climate data Long-term time-series stations Environment Canada and Quebec weather network For Gaspe Peninsula: Selection of the longer time series with the fewest missing data. Name Beginning Altitude (m) % no data Amqui ,1 Cap Madeleine ,5 Gaspé ,4 Lac Humqui ,1 Mont Joli ,9 St-Jean-de- Cherbourg ,3

Name Beginning Altitude (m) Changes in location (years) Autrans 1905 1090 1 (1939) La mure 1879 881

11 Climate data Long-term time-series stations The Météo France weather network For Vercors: Selection of the longer time series taking into account changes in location. Name Beginning Altitude (m) Changes in location (years) Autrans (1939) La mure Lus-la-Croix- Haute 4 (1928 ; 1955 ; 1994 ; 2011) (1981) Monestier (1942 ; 1962) Villard-de- Lans Saint-Jean en Royans (2005) (1947 ; 1979)

Climate data climate projections from numerical modeling DRIAS project (Providing

Societies and environment) : 1961-1990: reference period of model; 2021-2050: outputs

(B1=optimistic; A1B=moderate; A2=pessimistic) Altitude (m) Selection of ALADIN (Aire

12 Climate data climate projections from numerical modeling DRIAS project (Providing access to French Regionalized climate scenarios for the Impact and the Adaptation of Societies and environment) : : reference period of model; : outputs from B1, A1B and A2 IPCC scenarios. (B1=optimistic; A1B=moderate; A2=pessimistic) Altitude (m) Selection of ALADIN (Aire Limitée Adaptation dynamique Développement InterNational): Grenoble a regional model at 8km spatial resolution developed by Météo France.

13 Climate data climate projections from numerical modeling MRCC-v4.2 (Modèle Régional Canadien du Climat) at 45km spatial resolution, developed by Ouranos : reference period of model (20C3M data); : outputs from A2 IPCC scenarios. Selected grid points across the Gaspe Source:

A first look at the climate variability Interannual changes of relationships between Gaspe and Vercors temperature indices (1948-2012; from NCEP data) (anomalies are calculated relative to the

14 A first look at the climate variability Interannual changes of relationships between Gaspe and Vercors temperature indices ( ; from NCEP data) (anomalies are calculated relative to the normal; the thermal series are smoothed using a 24-months moving average; linear correlations between both indices are calculated with a moving window of 60 months) There are several consistent periods revealing great instability of peri-atlantic thermal relationships: instability of climate forcings on these two study regions.

15 A first look at the climate variability With especially a significant change of temperature anomalies after the late 90 s Gaspe - Vercors + Gaspe + Vercors Gaspe - Vercors - Gaspe + Vercors -

change from 1997, associated with a thermal continent/ocean dipole (opposition) in the Western Atlantic domain: a

16 Results from the observation period The spatio-temporal patterns of annual near-surface air temperature averages in North Atlantic Ocean and peripheral regions ( ) The first mode of variability (from a PCA with NCEP reanalyses) a major change from 1997, associated with a thermal continent/ocean dipole (opposition) in the Western Atlantic domain: a significant thermal shift in Gaspe. An increase in average annual Gaspe temperature PC1 Air temperature anomalies of Gaspe index

17 Results from the observation period Examples of mean annual temperature trend for 6 stations in Gaspe Peninsula Station Period of linear temperature trend Increase of temperature ( C) Amqui Cap Madeleine Gaspé Lac Humqui Mont Joli St-Jean de Cherbourg Cap Madeleine (34m asl) and Gaspe (2m asl) stations are lower and also those that record the lowest temperature increases.

18 Results from the observation period Verification to determine whether the temporal break is detected beyond the Gaspe area: comparison with other North American temperature time series Applying the Pettitt test to detect shift points in the temperature time series ( ): Amqui (Gaspe) Val d Or Airport (Western Québec) Shift in December 1997 K value (Pettitt test) Significativity at 99% level All statistical tests reveal a break in late 1997.

19 Results from the observation period The french pre-alpine temperature time series record rather a significant shift a decade before, in the late 80 s. Pettitt test calculated with temperature anomalies of the 2 regional indices ( ): Vercors: shift in July 1987 Gaspe: shift in December 1997 Vercors temperature index Gaspe temperature index

20 Results from the observation period Consequences of this temporal shift on frequency distribution of regional temperature Frequency Temperature classes ( C) After 1997, a significant warming in minimum temperatures.

21 Results from the observation period Change in average seasonal temperature regime in Gaspe Peninsula after 1997 Monthly Mean Temperatures ( C) difference between the two periods ( ) ( ) After 1997, a significant warming observed in autumn and especially in winter (an increase of more than 2 C in December and February).

correlated to the North Atlantic Oscillation (NAO) signature: interannual influences especially sensitive to the

22 Results from the observation period The spatio-temporal patterns of annual near-surface air temperature averages in North Atlantic Ocean and peripheral regions ( ) The second mode of variability An Atlantic dipole well correlated to the North Atlantic Oscillation (NAO) signature: interannual influences especially sensitive to the Vercors region, with a significant warming since the late 80 s. PC2 NAO Index Air temperature anomalies of Vercors index

Results from the observation period consequences of the late 80 s temperature shift on frequency distribution in Vercors Frequency Temperature

23 Results from the observation period consequences of the late 80 s temperature shift on frequency distribution in Vercors Frequency Temperature classes ( C) After 1987, a relatively similar statistical distribution, especially with an increase of the hottest average temperatures (above 14 C).

24 Results from the observation period Change in average seasonal temperature regime in Vercors Monthly Mean Temperatures ( C) difference between the 2 periods ( ) ( ) After 1987, a warming observed throughout the year, but especially significant during winter, spring and summer.

France / CNRM; model CNRM-CM3; in Kelvin) January

25 Projections of future changes Example of surface air temperature anomaly simulated for (from Meteo France / CNRM; model CNRM-CM3; in Kelvin) January simulations Scenario B1 Scenario A1B Scenario A2 July simulations K

Projections of future changes A clear and significant warming trend, but with seasonal and regional differences IN VERCORS: Example of minimum temperature recorded at Villard-de-Lans station

26 Projections of future changes A clear and significant warming trend, but with seasonal and regional differences IN VERCORS: Example of minimum temperature recorded at Villard-de-Lans station ( ; 1024m asl) and simulated at medium and long term by regional model ALADIN from the 3 main IPCC scenarios. Medium-term Long-term Villard-de-Lans The average annual minimum temperature is expected to increase from 1.5 to 1.8 C ( ) above the normal.

27 Projections of future changes A clear and significant warming trend, but with regional differences Trend in the Department of Drôme (South Vercors) Annual average temperature anomalies expected in the medium and long-term projections in ALADIN model and based on the A1B scenario (calculated from the department of Drôme relative to the reference period). Temperature anomalies ( C) Amplitude of all simulations By the end of the century, expected positive trend is about 2.5 C with the B1 scenario and about 4.5 C according to the A2 scenario.

periods according to the A1B scenario 1961-1990 2021-2050 2071-2100 T ( C)

28 Projections of future changes Example of annual mean surface air temperature in Drôme Department: evolution for and periods according to the A1B scenario T ( C) The increase in summer temperatures (JJA) should be greater than the winter ones (DJF).

29 Projections of future changes Annual average temperature simulated for Gaspe Peninsula ( ) from A2 scenario (with MRCC-v4.2 model) Normal periods T average ( C) An increase of 1.6 C in five decades; An exceptional year as 2010 (the warmest year since canadian records began in 1948) will be a normal year mid-century

30 Projections of future changes Warming does not affect the seasons in the same way JAS AMJ OND JFM Periods JFM AMJ JAS OND Seasonal warming involves many changes in thermal thresholds (especially for nivology), with many bioclimatic consequences.

31 Projections of future changes Example of the average seasonal temperature regime expected for the mid-century in Gaspe Peninsula Temperature increase ( C) Relatively warmer winter and summer (with an increase of more than 2 C in January and February).

32 Conclusion and perspectives On period, different phases of temperature covariations on both sides of the Atlantic: influence of the main patterns of ocean-atmosphere Atlantic variability. A difference of the major break of temperature time series: 1987 in Vercors and 1997 in Gaspe Peninsula. In Gaspe, especially a change in the colder temperatures, while all temperatures change in Vercors, including warmer. A significant and almost certain temperature increase of the two study areas for the medium and long term, but with seasonal differences.

33 Conclusion and perspectives Go beyond the temporal descriptive analysis to clarify ocean-atmosphere teleconnections involved in regional climate variability; Establish regional analysis from all the simulations of regional model simulations (intercomparison) and for different climate variables; Analyse the ecoclimatic consequences of major thermal observed and expected trends (impacts on some bioclimatic thresholds and snowpack).

34 Thank you View on high plateaux of Vercors and Mont Aiguille (2085m asl)

A downscaling and adjustment method for climate projections in mountainous regions

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