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[MIS01-13] Exposure of natural terrestrial systems in Northern Eurasia to hazardous climate events and their thresholds
Keywords:hazardous phenomena, biomes, natural terrestrial systems, Northern Eurasia, thresholds
Natural systems (ecosystems, species, populations) are subject to dangerous and unfavorable hydrometeorological phenomena in accordance with their geographical location. The diversity of terrestrial ecosystems in Northern Eurasia is extremely large and includes polar deserts; tundra; boreal, temperate broadleaved and subtropical forests; primary grasslands (steppes) and deserts. They divide on 66 plain and mountainous biomes in Russia.
The sensitivity to a dangerous phenomenon of a certain intensity in various components of one natural system may vary from no influence to complete destruction. The degree of threat can be assessed by identifying threshold values, when exceeded, significant damage is caused to at least one of the components of the natural system in the form of large-scale destructive disturbances, irreversible changes or the death of a significant proportion of the population of living organisms.
For natural systems, two levels of threshold values can be distinguished: the first is the actual possibility of causing significant damage; second, the consequences become catastrophic. Accordingly, depending on the threshold value, the potential for restoration of natural systems and timing changes, and the proportion of irreversible consequences increases.
Data on recorded hazardous phenomena within the biomes were collected from 223 meteorological stations and open databases of Russian Hydrometeorological Service and the Ministry of Emergency Situations. Data on the hazards’ impacts on natural systems are summarized from about 100 scientific publications.
As a result, we identified 21 dangerous phenomena: strong wind, tornado, heavy rain, heavy snow, large hail, severe blizzard, severe dust (sand) storm, ice crust formation, extreme frost, abnormally cold weather, extreme heat, abnormally hot weather, extreme fire danger, avalanches, dry winds (hot windy weather several days), atmospheric drought, high snow cover, floods (of various origins), mudflow, landslide, avalanches, abrasion of sea coasts.
For each event we selected two thresholds: first – intensity, from which the phenomena become harmful for natural systems or any them components; second – intensity of catastrophic consequences for terrestrial systems. For example, the average wind speed of 20 m/s was chosen as the threshold value of a dangerous phenomenon. The wind speed of at least 33 m/s was selected as a critical threshold value, which can cause the destruction of vegetation over a large area and the mass death of animals affected.
The intensity of six hazardous phenomena reached the first threshold value in all 66 biomes in Russia: very strong wind, abnormally cold and abnormally hot weather, atmospheric drought, severe glaze and frost deposits/ice crust and floods. Of these, only abnormally hot and abnormally cold weather reach the second threshold in all biomes. The fewest biomes (13) are affected by severe sandstorms.
For 9 hazardous phenomena, the second threshold is reached in more than 90% of biomes in which the first threshold of this phenomenon was recorded: very strong wind, tornado, large hail, abnormally cold and abnormally hot weather, extreme fire danger, dry wind, ice crust, high snow cover. For three phenomena, the second threshold was realized in less than 30% of biomes in which the first was recorded: extreme heat, atmospheric drought, abrasion of sea coasts. None of the biomes was susceptible to all of the hazards considered. The maximum number (20) happens in the mountain biomes of the Far East, and 18-20 – at the wide strip in the south of the country.
The maximum number of hazardous events reaching the second (critical) threshold value (17) also corresponds to the mountain biomes of Altai and around Lake Baikal. Generally, 40% of the territory exposed to 14-17 of them, and 50% - 10-13. The number of events does not mean, that the climate is mild. Particularly, biomes in High Arctic exposed to 6-9 critical hazardous events only.
The sensitivity to a dangerous phenomenon of a certain intensity in various components of one natural system may vary from no influence to complete destruction. The degree of threat can be assessed by identifying threshold values, when exceeded, significant damage is caused to at least one of the components of the natural system in the form of large-scale destructive disturbances, irreversible changes or the death of a significant proportion of the population of living organisms.
For natural systems, two levels of threshold values can be distinguished: the first is the actual possibility of causing significant damage; second, the consequences become catastrophic. Accordingly, depending on the threshold value, the potential for restoration of natural systems and timing changes, and the proportion of irreversible consequences increases.
Data on recorded hazardous phenomena within the biomes were collected from 223 meteorological stations and open databases of Russian Hydrometeorological Service and the Ministry of Emergency Situations. Data on the hazards’ impacts on natural systems are summarized from about 100 scientific publications.
As a result, we identified 21 dangerous phenomena: strong wind, tornado, heavy rain, heavy snow, large hail, severe blizzard, severe dust (sand) storm, ice crust formation, extreme frost, abnormally cold weather, extreme heat, abnormally hot weather, extreme fire danger, avalanches, dry winds (hot windy weather several days), atmospheric drought, high snow cover, floods (of various origins), mudflow, landslide, avalanches, abrasion of sea coasts.
For each event we selected two thresholds: first – intensity, from which the phenomena become harmful for natural systems or any them components; second – intensity of catastrophic consequences for terrestrial systems. For example, the average wind speed of 20 m/s was chosen as the threshold value of a dangerous phenomenon. The wind speed of at least 33 m/s was selected as a critical threshold value, which can cause the destruction of vegetation over a large area and the mass death of animals affected.
The intensity of six hazardous phenomena reached the first threshold value in all 66 biomes in Russia: very strong wind, abnormally cold and abnormally hot weather, atmospheric drought, severe glaze and frost deposits/ice crust and floods. Of these, only abnormally hot and abnormally cold weather reach the second threshold in all biomes. The fewest biomes (13) are affected by severe sandstorms.
For 9 hazardous phenomena, the second threshold is reached in more than 90% of biomes in which the first threshold of this phenomenon was recorded: very strong wind, tornado, large hail, abnormally cold and abnormally hot weather, extreme fire danger, dry wind, ice crust, high snow cover. For three phenomena, the second threshold was realized in less than 30% of biomes in which the first was recorded: extreme heat, atmospheric drought, abrasion of sea coasts. None of the biomes was susceptible to all of the hazards considered. The maximum number (20) happens in the mountain biomes of the Far East, and 18-20 – at the wide strip in the south of the country.
The maximum number of hazardous events reaching the second (critical) threshold value (17) also corresponds to the mountain biomes of Altai and around Lake Baikal. Generally, 40% of the territory exposed to 14-17 of them, and 50% - 10-13. The number of events does not mean, that the climate is mild. Particularly, biomes in High Arctic exposed to 6-9 critical hazardous events only.