Trend analysis of fire season length and extreme fire weather in North America between 1979 and 2015

2017 ◽  
Vol 26 (12) ◽  
pp. 1009 ◽  
Author(s):  
Piyush Jain ◽  
Xianli Wang ◽  
Mike D. Flannigan
Keyword(s):  
North America ◽  
Statistical Significance ◽  
Kendall Test ◽  
Fire Season ◽  
Fire Weather ◽  
Season Length ◽  
Eastern Canada ◽  
Reanalysis Dataset ◽  
Fire Weather Index ◽  
Extreme Fire

We have constructed a fire weather climatology over North America from 1979 to 2015 using the North American Regional Reanalysis dataset and the Canadian Fire Weather Index (FWI) System. We tested for the presence of trends in potential fire season length, based on a meteorological definition, and extreme fire weather using the non-parametric Theil–Sen slope estimator and Mann–Kendall test. Applying field significance testing (i.e. joint significance of multiple tests) allowed the identification of the locations of significant trends, taking into account spatial correlations. Fire season length was found to be increasing over large areas of North America, especially in eastern Canada and the south-western US, which is consistent with a later fire season end and an earlier fire season start. Both positive and negative trends in potential fire spread days and the 99th percentile of FWI occurred in Canada and the contiguous United States, although the trends of largest magnitude and statistical significance were mostly positive. In contrast, the proportion of trends with significant decreases in these variables were much lower, indicating an overall increase in extreme fire weather. The smaller proportion of significant positive trends found over Canada reflects the truncation of the time series, necessary because assimilation of precipitation observations over Canada ceased in the reanalysis post-2002.

scholarly journals Temporal variations and change in forest fire danger in Europe for 1960–2012

2014 ◽  
Vol 14 (6) ◽  
pp. 1477-1490 ◽  
Author(s):  
A. Venäläinen ◽  
N. Korhonen ◽  
O. Hyvärinen ◽  
N. Koutsias ◽  
F. Xystrakis ◽  
...  
Keyword(s):  
Forest Fire ◽  
Forest Fires ◽  
National Level ◽  
Temporal Variations ◽  
Fire Danger ◽  
Fire Season ◽  
Fire Weather ◽  
Fire Weather Index ◽  
Current Season ◽  
Forest Fire Danger

Abstract. Understanding how fire weather danger indices changed in the past and how such changes affected forest fire activity is important in a changing climate. We used the Canadian Fire Weather Index (FWI), calculated from two reanalysis data sets, ERA-40 and ERA Interim, to examine the temporal variation of forest fire danger in Europe in 1960–2012. Additionally, we used national forest fire statistics from Greece, Spain and Finland to examine the relationship between fire danger and fires. There is no obvious trend in fire danger for the time period covered by ERA-40 (1960–1999), whereas for the period 1980–2012 covered by ERA Interim, the mean FWI shows an increasing trend for southern and eastern Europe which is significant at the 99% confidence level. The cross correlations calculated at the national level in Greece, Spain and Finland between total area burned and mean FWI of the current season is of the order of 0.6, demonstrating the extent to which the current fire-season weather can explain forest fires. To summarize, fire risk is multifaceted, and while climate is a major determinant, other factors can contribute to it, either positively or negatively.

scholarly journals Increased trends in global extreme fire weather driven predominantly by atmospheric humidity and temperature

2021 ◽  
Author(s):  
Piyush Jain ◽  
Dante Castellanos-Acuna ◽  
Sean Coogan ◽  
John Abatzoglou ◽  
Mike Flannigan
Keyword(s):  
Global Analysis ◽  
Vapour Pressure Deficit ◽  
Fire Risk ◽  
Dew Point ◽  
Fire Weather ◽  
Atmospheric Humidity ◽  
Weather Index ◽  
Fire Weather Index ◽  
Temperature Trends ◽  
Extreme Fire

Abstract Climate and weather greatly influence wildfire, and recent increases in wildfire activity have been linked to climate change. However, the atmospheric drivers of observed changes have not been articulated globally. We present a global analysis of trends in extreme fire weather from 1979–2020. Significant increases in extreme (95th percentile) annual values of the Fire Weather Index (FWI95), Initial Spread Index (ISI95), and Vapour Pressure Deficit (VPD95) occurred over 26.0%, 26.1%, and 46.1% of the global burnable landmass, respectively. Significant trends corresponded to a 35.8%, 36.0%, and 21.4% increase in mean global FWI95, ISI95, and VPD95, respectively. Relative humidity and temperature were identified as the drivers of significant trends in FWI95 and ISI95 in most regions, largely where temperature trends outpaced dew point trends. We identified relatively few regions in which wind speed or precipitation were drivers. These findings have wide-ranging implications for understanding fire risk in a changing climate.

scholarly journals Attribution of the Australian bushfire risk to anthropogenic climate change

2020 ◽  
Author(s):  
Geert Jan van Oldenborgh ◽  
Folmer Krikken ◽  
Sophie Lewis ◽  
Nicholas J. Leach ◽  
Flavio Lehner ◽  
...  
Keyword(s):  
Climate Change ◽  
Climate Models ◽  
Southern Annular Mode ◽  
Warming Trend ◽  
Anthropogenic Climate Change ◽  
Fire Season ◽  
Fire Weather ◽  
Weather Index ◽  
Fire Weather Index

Abstract. Disastrous bushfires during the last months of 2019 and January 2020 affected Australia, raising the question to what extent the risk of these fires was exacerbated by anthropogenic climate change. To answer the question for southeastern Australia, where fires were particularly severe, affecting people and ecosystems, we use a physically-based index of fire weather, the Fire Weather Index, long-term observations of heat and drought, and eleven large ensembles of state-of-the-art climate models. In agreement with previous analyses we find that heat extremes have become more likely by at least a factor two due to the long-term warming trend. However, current climate models overestimate variability and tend to underestimate the long-term trend in these extremes, so the true change in the likelihood of extreme heat could be larger. We do not find an attributable trend in either extreme annual drought or the driest month of the fire season September–February. The observations, however, show a weak drying trend in the annual mean. Finally, we find large trends in the Fire Weather Index in the ERA5 reanalysis, and a smaller but significant increase by at least 30 % in the models. The trend is mainly driven by the increase of temperature extremes and hence also likely underestimated. For the 2019/20 season more than half of the July–December drought was driven by record excursions of the Indian Ocean dipole and Southern Annular Mode. These factors are included in the analysis. The study reveals the complexity of the 2019/20 bushfire event, with some, but not all drivers showing an imprint of anthropogenic climate change.

Changes in forest fire danger for south-western China in the 21st century

2014 ◽  
Vol 23 (2) ◽  
pp. 185 ◽  
Author(s):  
Xiao-rui Tian ◽  
Feng-jun Zhao ◽  
Li-fu Shu ◽  
Ming-yu Wang
Keyword(s):  
Climate Change ◽  
Forest Fire ◽  
Eastern China ◽  
Fire Danger ◽  
Western China ◽  
Fire Season ◽  
Climate Change Scenarios ◽  
Fire Weather Index ◽  
Forest Fire Danger ◽  
Extreme Fire

This paper predicts future changes in fire danger and the fire season in the current century for south-western China under two different climate change scenarios. The fire weather index (FWI) system calculated from daily outputs of a regional climate model with a horizontal resolution of 50×50km was used to assess fire danger. Temperature and precipitation demonstrated a gradually increasing trend for the future. Forest fire statistics for 1987–2011 revealed that the FWI, initial spread index and seasonal severity rating were significantly related to the number of forest fires between 100 and 1000ha in size. Over three future periods, the FWI component indices will increase greatly. The mean FWI value will increase by 0.83–1.85, 1.83–2.91 and 3.33–3.97 in the periods 2011–2040, 2041–2070 and 2071–2100. The regions with predicted FWI increases are mainly in central and south-eastern China. The fire season (including days with high, very high and extreme fire danger ratings) will be prolonged by 9–13, 18–21 and 28–31 days over these periods. This fire season extension will mainly be due to days with an extreme fire danger rating. Considering predicted future changes in the forest fire danger rating and the fire season, it is suggested that climate change adaptation measures be implemented.

scholarly journals Verification of WRF modelled fire weather in the 2009–10 New Zealand fire season

2014 ◽  
Vol 23 (1) ◽  
pp. 34 ◽  
Author(s):  
C. C. Simpson ◽  
H. G. Pearce ◽  
A. P. Sturman ◽  
P. Zawar-Reza
Keyword(s):  
New Zealand ◽  
Weather Conditions ◽  
Model Error ◽  
Dew Point ◽  
Fire Season ◽  
Fire Weather ◽  
Fire Weather Index ◽  
Wind Speeds ◽  
Air Temperatures ◽  
Weather Stations

The Weather Research and Forecasting (WRF) mesoscale model was used to simulate the fire weather conditions for the 2009–10 wildland fire season in New Zealand. The suitability of WRF to simulate the high-end fire weather conditions for this period was assessed through direct comparison with observational data taken from 23 surface and two upper-air stations located across New Zealand. The weather variables and fire weather indices considered in the verification were the 1200 hours NZST air temperature, relative humidity, wind speed and direction, 24-h rainfall, New Zealand Fire Weather Index (FWI) and Continuous Haines Index (CHI). On observed high-end fire weather days, the model under-predicted the air temperatures and relative humidities, and over-predicted the wind speeds and 24-h rainfall at most weather stations. The results demonstrated that although WRF is suitable for modelling the air temperatures, there are issues with modelling the wind speeds and rainfall quantities. The model error in the wind speeds and 24-h rainfall contributed significantly towards the model under-prediction of the FWI on observed high-end fire weather days. In addition, the model was not suitable for predicting the number of high-end fire weather days at most weather stations, which represents a serious operational limitation of the WRF model for fire management applications. Finally, the modelled CHI values were only in moderate agreement with the observed values, principally due to the model error in the dew point depression at 850hPa.

Fire weather index system components for large fires in the Canadian boreal forest

2004 ◽  
Vol 13 (4) ◽  
pp. 391 ◽  
Author(s):  
B. D. Amiro ◽  
K. A. Logan ◽  
B. M. Wotton ◽  
M. D. Flannigan ◽  
J. B. Todd ◽  
...  
Keyword(s):  
Weather Conditions ◽  
Fire Season ◽  
Fire Weather ◽  
Fuel Moisture ◽  
Weather Index ◽  
Fire Weather Index ◽  
System Parameters ◽  
System Components ◽  
Large Fires ◽  
Canadian Boreal Forest

Canadian Fire Weather Index (FWI) System components and head fire intensities were calculated for fires greater than 2 km2 in size for the boreal and taiga ecozones of Canada from 1959 to 1999. The highest noon-hour values were analysed that occurred during the first 21 days of each of 9333 fires. Depending on ecozone, the means of the FWI System parameters ranged from: fine fuel moisture code (FFMC), 90 to 92 (82 to 96 for individual fires); duff moisture code (DMC), 38 to 78 (10 to 140 for individual fires); drought code (DC), 210 to 372 (50 to 600 for individual fires); and fire weather index, 20 to 33 (5 to 60 for individual fires). Fine fuel moisture code decreased, DMC had a mid-season peak, and DC increased through the fire season. Mean head fire intensities ranged from 10 to 28 MW m−1 in the boreal spruce fuel type, showing that most large fires exhibit crown fire behaviour. Intensities of individual fires can exceed 60 MW m−1. Most FWI System parameters did not show trends over the 41-year period because of large inter-annual variability. A changing climate is expected to create future weather conditions more conducive to fire throughout much of Canada but clear changes have not yet occurred.

Wildfires and the Canadian Forest Fire Weather Index system for the Daxing'anling region of China

2011 ◽  
Vol 20 (8) ◽  
pp. 963 ◽  
Author(s):  
Xiaorui Tian ◽  
Douglas J. McRae ◽  
Jizhong Jin ◽  
Lifu Shu ◽  
Fengjun Zhao ◽  
...  
Keyword(s):  
Forest Fire ◽  
Forest Fires ◽  
Coniferous Forest ◽  
Northern China ◽  
Fire Danger ◽  
Fire Season ◽  
Fire Weather ◽  
Burnt Area ◽  
Weather Index ◽  
Fire Weather Index

The Canadian Forest Fire Weather Index (FWI) system was evaluated for the Daxing'anling region of northern China for the 1987–2006 fire seasons. The FWI system reflected the regional fire danger and could be effectively used there in wildfire management. The various FWI system components were classified into classes (i.e. low to extreme) for fire conditions found in the region. A total of 81.1% of the fires occurred in the high, very high and extreme fire danger classes, in which 73.9% of the fires occurred in the spring (0.1, 9.5, 33.3 and 33.1% in March, April, May and June). Large wildfires greater than 200 ha in area (16.7% of the total) burnt 99.2% of the total burnt area. Lightning was the main ignition source for 57.1% of the total fires. Result show that forest fires mainly occurred in deciduous coniferous forest (61.3%), grass (23.9%) and deciduous broad leaved forest (8.0%). A bimodal fire season was detected, with peaks in May and October. The components of FWI system were good indicators of fire danger in the Daxing'anling region of China and could be used to build a working fire danger rating system for the region.

scholarly journals A high-resolution reanalysis of global fire weather from 1979 to 2018 – Overwintering the Drought Code

2020 ◽  
Author(s):  
Megan McElhinny ◽  
Justin F. Beckers ◽  
Chelene Hanes ◽  
Mike Flannigan ◽  
Piyush Jain
Keyword(s):  
High Resolution ◽  
Fire Behavior ◽  
Fire Season ◽  
Fire Weather ◽  
Weather Index ◽  
Fire Weather Index ◽  
Start Up ◽  
System Calculation ◽  
Second Procedure ◽  
Temporal Coverage

Abstract. We present a global high-resolution calculation of the Canadian Fire Weather Index (FWI) System Indices using surface meteorology from the ERA5-HRS reanalysis for 1979–2018. ERA5-HRS represents an improved dataset compared to several other reanalyses in terms of accuracy, as well as spatial and temporal coverage. The FWI calculation is performed using two different procedures for setting the start-up value of the Drought Code (DC) at the beginning of the fire season. The first procedure, which accounts for the effects of inter-seasonal drought, overwinters the DC by adjusting the fall DC value with a fraction of accumulated overwinter precipitation. The second procedure sets the DC to its default start-up value (i.e. 15) at the start of each fire season. We validate the FWI values over Canada using station observations from Environment and Climate Change Canada and find generally good agreement (mean Spearman correlation of 0.77). We also show that significant differences in early season DC and FWI values can occur when the FWI System calculation is started using the overwintered versus default DC values, as is highlighted by an example from 2016 over North America. The FWI System moisture codes and fire behavior indices are made available for both versions of the calculation at https://doi.org/10.5281/zenodo.3626193 (McElhinny et al., 2020), although we recommend using codes and indices calculated with the overwintered DC, unless specific research requirements dictate otherwise.

scholarly journals Combining the Monthly Drought Code and Paleoecological Data to Assess Holocene Climate Impact on Mediterranean Fire Regime

Fire ◽  
2020 ◽  
Vol 3 (2) ◽  
pp. 8 ◽  
Author(s):  
Marion Lestienne ◽  
Christelle Hély ◽  
Thomas Curt ◽  
Isabelle Jouffroy-Bapicot ◽  
Boris Vannière
Keyword(s):  
Climate Model ◽  
Fire Regime ◽  
Fire Hazard ◽  
Data Availability ◽  
Fire Season ◽  
Season Length ◽  
Fire Weather Index ◽  
The Past ◽  
Current Period ◽  
Daily Weather Data

Currently, indexes from the Fire Weather Index System (FWI) are used to predict the daily fire hazard, but there is no reliable index available in the Mediterranean region to be compared with paleofire records and check for their long-term reliability. In order to assess the past fire hazard and the fire-season length, based on data availability and requirements for fire index computation, we first chose and tested the efficiency of the Drought Code (DC) in Corsica (the main French Mediterranean fire-prone region) over the current period (1979–2016). We then used DC as a benchmark to assess the efficiency of the Monthly Drought Code (MDC) and used it to assess the Fire-Season Length (FSL), which were both used to characterize the fire hazard. Finally, we computed the Holocene MDC and FSL based on the HadCM3B-M1 climate model (three dimensional, fully dynamic, coupled atmosphere-ocean global climate model without flux adjustment) datasets and compared both index trends with those from proxies of paleofire, vegetation, and land use retrieved from sedimentary records in three Corsican lakes (Bastani, Nino, and Creno). Our strategy was to (i) assess fire hazard without the constraint of the daily weather-data requirement, (ii) reconstruct Holocene fire hazard from a climate perspective, and (iii) discuss the role of climate and human fire drivers based on the MDC-Paleofire proxy comparisons. Using both the Prométhée fire database and the ERA-Interim climate database over Corsica for the current period, we showed that DC values higher than 405 units efficiently discriminated fire-days from no-fire-days. The equivalent threshold value from MDC was set at 300 units. MDC and FSL indexes calculated for each of the past 11 millennia Before Present (11 ka BP) showed high values before 7 ka BP (above 300 units for MDC) and then lower values for the mid- to late Holocene (below 300 units for MDC). Climate appeared as a key driver to predict fire occurrences, promoting fires between 11 and 8 ka BP when summers were warmer than the current ones and reducing fire hazard after 7–6 ka BP due to wetter conditions. Since 5 ka BP, humans have taken control of the fire regime through agro-pastoralism, favoring large and/or frequent events despite less fire-prone climate conditions. The current fire hazard and fire-season length computed over the last few decades (1979–2016) both reported values that were respectively higher and longer than those assessed for the previous six millennia at least and comparable for those before 7 ka BP. For the next decades, due to climate warming associated with land abandonment (fuel accumulation) and the increase in human-related sources of ignition, we can expect an increase in fire hazard and larger fire events.

Development of a common definition approach for multi-event attribution of fire weather extremes

2021 ◽  
Author(s):  
Zhongwei Liu ◽  
Jonathan Eden ◽  
Bastien Dieppois ◽  
Matthew Blackett
Keyword(s):  
Climate Model ◽  
Grid Point ◽  
Management Strategies ◽  
Fire Danger ◽  
Fire Weather ◽  
Weather Extremes ◽  
Fire Weather Index ◽  
Fire Emissions ◽  
Common Definition ◽  
Extreme Fire

<p>In response to the occurrence of large wildfire events across both hemispheres in recent years, the effort to understand the extent to which climate change may be altering the frequency of fire-conducive meteorological conditions has become an emerging subfield of attribution science. However, to date, the relative paucity of wildfire attribution studies, coupled with limited observational records, makes it difficult to draw solid and collective conclusions to better inform forest management strategies. The inter-study differences that emerge due to the choice of methodology and event definition are common to many attribution studies; for wildfire attribution in particular, the lack of consensus on how fire danger should be defined in a meteorological context presents an additional challenge.</p><p>Here, we present a framework for the simultaneous attribution of multiple extreme fire weather episodes of using an empirical-statistical methodology. Key to this framework is the development of a common spatiotemporal definition for extreme fire weather events. With reference to the fourth version of Global Fire Emissions Dataset (GFED4), we focus on all parts of the world that have experienced fires during the period 1995-2016. At each target grid point, we fit a Generalized Extreme Value (GEV) distribution, scaled by global mean surface temperature (smoothed over 4 years), to the annual maxima of a series of reanalysis-derived fire danger indicators (including the fire weather index) for the period 1980-2018. Using global maps of risk ratios and percentage of changes, we quantify the influence of recent global warming on the frequency and magnitude of fire weather extremes according to a common ‘event type’ definition, irrespective of their spatiotemporal occurrence. We subsequently conduct a collective attribution analysis of a series of recent exceptional events. We conclude with suggestions for further application to climate model ensembles and a discussion of the potential of our findings to inform decision-makers and practitioners.</p>

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