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Assessment of fire risk in boreal forests under the present-day and future climate Andrea Vajda, Ari Venäläinen and Kirsti Jylhä Finnish Meteorological.

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Presentation on theme: "Assessment of fire risk in boreal forests under the present-day and future climate Andrea Vajda, Ari Venäläinen and Kirsti Jylhä Finnish Meteorological."— Presentation transcript:

1 Assessment of fire risk in boreal forests under the present-day and future climate Andrea Vajda, Ari Venäläinen and Kirsti Jylhä Finnish Meteorological Institute (FMI) ENSEMBLES Annual Meeting, Lund, 20-23 Nov 2006 WP6.2 – Linking impact models to probabilistic scenarios of climate

2 Outline FMI contribution to deliverable D6.9 Report on an intercomparison study of modelled, Europe-wide forest fire risk for present day conditions by Giannakopoulos et al. (NOA & FMI) (month 24) The impact of climate change on forest fire risk in northern Europe: some first estimates Future plans in ENSEMBLES

3 Photo © Krister Sanmark Boreal forests cover nearly 78% of total land area in Finland Photo © A. Drebs Finnish fire statistics 2001-2006 0 10 20 30 40 50 60 70 Apr 1May 1June 1July 1Aug 1Sep 1Oct 1 Number of fires 0 20 40 60 80 100 120 140 Apr 1May 1June 1July 1Aug 1Sep 1Oct 1 Area burned (ha) Average daily number of fires in April - October Average daily area burned Annual number of fires and area burned 0 1000 2000 3000 4000 5000 6000 7000 200120022003200420052006 No. of cases 0 500 1000 1500 2000 2500 Burned area (ha) No. of fires Area burnt The average annual number of fires: about 3100 The average annual area burned: about 800 ha => The mean area burned per event: 0.25 ha 18% of fires 0.1 ha 0.3% of fires 10 ha The frequency of fires is highest and the total area burned is largest in May

4 Smoke in Helsinki in summer 2006 due to forest fires from abroad Helsinki 9 Aug 2006 at 1 pmHelsinki 9 Aug 2006 at 2 pm Photo © Pia Anttila One hour later (a shift in wind direction)

5 Evaluation of two forest fire danger indices in the boreal forests environment (Finland) The Finnish Forest Fire Index (FFI): - Soil surface moisture as an indicator of the fire risk The Canadian Fire Weather Index (FWI): - Forest fuel moisture content; adjustment to the Finnish conditions Fire danger classes FFI (6 classes) FWI (5 classes) 6 very high 5 – 5.9 high 4 – 4.9 moderately high 3 – 3.9 moderately low 2 – 2.9 low 1 – 1.9 very low >25 extreme 18 – 24.9 high 10 – 17.9 medium 2 – 9.9 low 0 – 1.9 very low Fire potential threshold for Pinus sylvestris stand

6 Correlation between the Finnish and Canadian fire indices based on station data in Finland in 1961 – 2005 (April–September) A station in southern Finland A station in northern Finland Finnish index FFI Canadian index FWI The forest fire risk decreases northwards FWI responded more rapidly to the meteorological variations (i.e. precipitation) than FFI. In northern and central Finland FWI indicated a fire risk more often than FFI, and vice versa in southern Finland

7 Monthly distribution of days with FWI and/or FFI indicating fire risk (FWI>10, FFI4; central Finland) Largest deviations between FFI and FWI in early spring and in autumn Apr May June July Aug Sep FWI and FFIonly FFIonly FWI In about 50-60% of the cases both indices indicated a fire risk Relative frequency (%)

8 Comparison of fire indices and observed fire events size of the fires: FFI FWI no fire risk a fire risk Frequency distribution (%) 0.1-0.9 ha 1 ha size of the fires: 0.1-0.9 ha 1 ha 54% of the fires 0.1 ha occurred when FFI indicated fire risk 64% of the fires 0.1 ha occurred when FWI indicated fire risk The fire indices predict the favourable meteorological conditions for the occurrence of fires, but they are not predictors of fire events Human behaviour, etc

9 The impact of climate change on forest fire risk in northern Europe – a preliminary study

10 R1d MAM CDD MAM R1d JJA CDD JJA Multi-model means based on RCM-H-A2 runs MAM and JJA changes (%) in the max 1-day precipitation (left) and max length of dry spells (right) by 2071-2100 increase decrease increase decrease For R1d: For CDD:

11 observations RCA3-E-A2 scenario RCA3-E-B2 scenario Temporal variation of the annual number of days with a fire risk (FFI4) in Helsinki during 1961-2100 based on: Changes in time of the average annual number of days with a high or a very high forest fire risk (FFI 5) The impact of climate change on forest fire risk in northern Europe – a preliminary study (cont.) Latitude range in Scandinavia and the Baltic countries

12 The annual number of days with a forest fire risk (FFI 4) – preliminary results Based on the RCA3-E-A2 simulation 2001–2025

13 The annual number of days with a forest fire risk (FFI 4) – preliminary results Based on the RCA3-E-A2 simulation 2026–2050

14 The annual number of days with a forest fire risk (FFI 4) – preliminary results Based on the RCA3-E-A2 simulation 2051–2075

15 The annual number of days with a forest fire risk (FFI 4) – preliminary results Based on the RCA3-E-A2 simulation 2076–2100

16 Future plans in the ENSEMBLES project To produce new estimates of the impact of climate change on forest fire risk in northern Europe on the basis of - various future climate projections and - the Finnish Forest Fire Index (FFI) To evaluate the impact of the extreme climate events on soil temperature and soil moisture - Simulations using a coupled heat and mass transfer model for soil-plant-atmosphere system* (COUP model) - Measured meteorological data / climate models output data - Findings to be compared against results from the Finnish forest fire danger forecasting system ___ * Jansson, P.E. & Karlberg, L., 2001: Coupled heat and mass transfer model for soil-plant-atmosphere systems. Royal Institute of Technology, Dept of Civil and Environmental Engineering, Stockholm, 321 pp.

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18 Year-to-year variation of the onset and end of the fire season ** 5 consecutive days with FWI>11, using a 7 days moving average Calendar day FFI start date* FFI end date* FWI start date** FWI end date** * first and last days with FFI=4 FWI appeared to respond very quickly to the variation of precipitation events, while FFI indicated smoother changes.


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