SUMMARY: To mitigate the influence of greenhouse gases (GHG) and climate change on the unique boreal landscape in Estonia, a better understanding is needed of Estonian GHG emissions. Such data are especially valuable now, when privatization and ongoing process of restructuring of socioeconomic system creates a good possibility for decreasing GHG emissions. During the time when Estonia belonged to the previous U.S.S.R., the emissions and environment data had, as a rule, only restricted use. Therefore the present study, supported by U.S. Country Studies Program, is the first attempt to compile an inventory of GHG emissions in Estonia.
Estonia is situated in northwestern part of the flat East European plain, remaining entirely within the drainage area of the Baltic Sea. The coastline length is 3,794 km. The total area of Estonia is 45,215 km2, of which 4,132 km² (9.2 percent) is made up of more than 1,500 islands and islets. Estonia is characterized by a flat topography. The average elevation is 50 m, with the highest point being 318 m above sea level. Of the total population of 1,575,000 persons (1990 census), 71.4 percent live in urban areas. The population density is 35 persons/km² . Fifty-one percent of the population live in the five largest cities (Tallinn 484,400, Tartu 115,400, Narva 82,300, Kohtla‹ Jä rve 76,800 and Pä rnu 54,200).
Estonia belongs to Atlantic continental region of the temperate zone, which is characterized by rather warm summers and comparatively mild winters. Since the annual amount of precipitation exceeds evaporation by a factor of two, the climate is excessively damp. The amount of solar radiation varies widely during the year. Although not very large in area, Estonia is relatively rich in natural resources, both mineral and biological, which have been and will be the basis of the Estonian economy. The production and processing of mineral resources give a considerable share of the gross national product but cause serious environmental problems. One of the most important ones is connected with the excavation of oil shale and use for energy production, which is accompanied by emission of GHG and fly ash, decline of ground water table, degradation of the quality of the fields and forests, as well as direct reduction of useful land due to the subsidence of soil and the deposition of waste (Punning, 1994).
The most important branch of industry in Estonia is energy. The total power yield of the Estonia and Baltic Thermal Power Plant is about 3,000 MW. Approximately 75 percent of the pollutants (CO2, SO2, NOx, fly-ash) are emitted by the Baltic and Estonian TPP, which ranks among the ten biggest sources of air pollution in Europe.
The biggest sources of GHG in Estonia are energy and industry. In 1990 the Estonian energy system consumed a total at 452,000 TJ of fuel per year. Estonia satisfies most of its energy demand by using fossil fuels. In 1990 oil shale constituted approximately 52 percent of the energy balance; heavy and light oil, 31 percent; natural gas, 11 percent; coal, 2.7 percent; and peat, wood, and wood waste, 3.3 percent. During oil shale combustion, CO2 is formed not only as a burning product of organic carbon, but also as a decomposition product of the carbonate fraction. In the years 1990‹ 93, electricity production has decreased considerably due to economical depression in Estonia, Latvia, Lithuania, and Russia. This caused a decrease in oil shale consumption for electricity generation from 22.4 million tons in 1990 to 15 million tons in 1993. At the same time emissions from transportation increased accordingly with the increasing number of vehicles.
The territory of arable land is 1,130,000 hectares, with the total cultivated area is 1,110,000 hectares. Main GHG sources in the agriculture sector in Estonia are animal husbandry and use of fertilizers.
The forest land area makes up 47.7 percent of the Estonian territory. During the past half- century the area of forest stands has more than doubled, and the growing stock on it has increased 2.4 times (Table 1). Estonian forests belong to the zone of mixed and coniferous forests with relatively favorable growth conditions. Predominant tree species are Norway spruce, Scotch pine, and birch.
The peatland area is approximately 10,000 km2, corresponding to 22 percent of the territory (partly coinciding with forest areas); total peat reserves are approximately 2.7 billion metric ton. At present 1.4 million ton of peat (mainly milled peat) is extracted annually (Estonia, 1994). During the last decades, Estonian peatlands have been significantly influenced by amelioration activities.
An inventory of GHG emissions and removals by sinks has been performed accordingly to the Intergovernmental Panel on Climate Change (IPCC) preliminary methodology. In each sector having importance in the GHG inventory in Estonia (energy, industry, transport, forestry, agriculture, wetlands), step-by-step assembly, documentation, and transmittal of the national inventory of GHG was provided for the baseline year 1990. The data were entered on the IPCC worksheets and then, if necessary, the data were checked and corrected. Due to the importance of wetlands in Estonia and lack of methodical approaches in IPCC Guidelines (1994), a special methodology was worked out for inventory of GHG in this sector. The reliability of the data in different sectors varies largely. While reliable data about the conversion of domestic fossil fuel resources like oil shale are available, data on other sources (imported fossil fuels, private fellings of fuelwood) are less reliable (Statistical Yearbook, 1991‹ 94).
The methodology applied in the present inventory does not differ from that recommended in the IPCC Guidelines. The assumptions and default data (recommended by IPCC Guidelines, 1994) have been used when national data or assumption were not available.
It should be stressed that statistical data on the Estonian forests is satisfactory for calculating GHG emissions with the simplified IPCC methods.
Finally the fundamental bases for the methodology rests upon two linked themes:
Agriculture
The main GHG sources in agriculture for Estonia are animal
husbandry and use of
fertilizers.
According to the IPCC methodology, more attention was paid to
CH4 and
N2O emissions. Data concerning soil properties and
location was collected.
Emissions
from burning straw and other plant residues were not calculated in
the present inventory
as the
statistical data were not available.
As a result of the drainage of virgin peatlands the accumulation of organic matter ceases and mineralization of the organic matter begins. For several decades, the breakdown of peat deposit and peat losses on fenlands ameliorated for agricultural purposes is monitored in Estonia. It is shown that the mineralization of organic matter is about 15 to 20 tons per hectare per year during the first decade after the establishment of an amelioration system (Tomberg, 1992). Later it is stabilized and depending on the type of exploitation (crop field, grassland, pasture) the mineralization is between 5 and 15 tons per hectare per year. The mean level is 8 tons per hectare per year. As shown in several studies, the rate of mineralization of the peat in bogs and swamps is probably on the same level as in fenlands (Tomberg, 1992).
Biomass fuel is used in form of fuelwood and wood waste. For 1990 CO2 emissions from biomass consumption were 847 Gg. Fuelwood burned one year but regrown the next year only recycles carbon. As a result, carbon dioxide emissions from biomass have been estimated separately from fossil fuel-based emissions and are not included in national totals.
Approximately 68 percent of Estonian energy is produced through the combustion of oil shale. The remaining 32 percent comes from heavy fuel oil, natural gas or other energy sources such as coal, light fuel oil, or LPG. The energy conversion sector accounts 77 percent of Estonian emissions from fossil fuel consumption, making it the largest source of CO2 emissions. Oil shale across all sectors of the economy was responsible for about 76 percent of total Estonian energy- related CO2 emissions with heavy oil accounting for 14 percent; natural gas, 6 percent; and other sources, 4 percent.
The main production processes that emit CO2 in Estonia include cement production, lime production, limestone consumption. Total CO2 emissions from these sources were approximately 627 Gg in 1990, accounting for 1.7 percent of total emissions of carbon dioxide. Cement and lime production are main industrial processes of carbon dioxide emissions.
Emissions from mobile sources are estimated by major transportation activity (passenger cars, buses, lorries, special vehicles, motorcycles, tractors, small excavators, diesel locomotives, air transport), where several major fuel types, including gasoline, diesel fuel, jet kerosene, natural gas liquids, other kerosene and LPG are considered. Road transportation accounts for the majority of mobile source fuel consumption, and the majority of mobile source emissions. Table 4 summarizes emissions from mobile sources. Total emissions from mobile sources in 1990 were 279 Gg of CO, 53 Gg of NOx , 3.4 Gg of CH4, and 37 Gg of NMVOC. The number of vehicles is increasing very quickly in Estonia. Among them more used old cars and lorries are imported from abroad. Therefore emissions from mobile sources show a continual tendency to increase.
Methane will be emitted as a result of energy production, transmission, storage, and distribution activities, as well as from municipal landfills, covering large territories in Estonia (Table 5). Methane production typically begins one or two years after waste placement in landfill and may last a long time (more than 50 years). Methane may be recovered for use as an energy source. The availability of data on sources and sinks of GHG is best in the energy sector and not so good for wastes and solvents.
During the last half-century the area of forest stands has more than doubled (in 1935‹ 20.2 percent; in 1993‹ 47.7 percent) and will be increasing for the nearest future in Estonia (Karoles et al., 1994). As a results of biological process (e.g., growth, mortality) and human activity (e.g., harvesting, thinning, etc.) the carbon balance in forest ecosystem has been changed, already if compared with the situation in the past and will be changed in the future due to alterations in Estonian forestry .
Despite the small territory of Estonia, the forests growing here are rather diverse. The great variability brought about by natural conditions (soil, relief, and climatic ) is increased by the fact that the majority of the forests of Estonia have been affected by man's activities in varying degrees and ways (cutting, drainage, fires, etc.). The carbon content in forest soils varies from 44 to 192 tons per hectare.
The total carbon flux in the Estonian forests presented in estimates for 1990 (± 2 years) is based on a total accounting of biomass carbon stored in aboveground biomass of trees, soil carbon, as well as carbon in product pools. The annual carbon flux from Estonian forest is estimated to have been a net sequestration of carbon from the atmosphere to the biosphere. The total removal of carbon from atmosphere to forests was estimated to be 3,094.6 Gg, including 2,476.6 Gg removed by trees and 617.9 Gg by soils (Table 6).
Commercial harvest and management of various kinds make up a large majority of total forests biomass losses. Depending on the level of management, the annual rate of removals and emissions may be changed. Carbon annual emission rates from Estonian forests are estimated to be 926.3 Gg. The harvested timber and fuelwood effectively result in immediate carbon emissions of 769.6 Gg. Additional carbon flux from forests have been estimated for the onsite burning of branches, barks, and other wood wastes at 9.5 Gg. By forest conversion some of the biomass remains on the ground (stumps) where it decays slowly and 9.2 Gg carbon is released to the atmosphere due to the decay. A rather high amount of carbon is released to the atmosphere from the forest soil. This indicates that less carbon is actually emitted to the atmosphere from the Estonian productive forests than accumulated during the inventory period. Due to the carbon removal processes the net annual accumulation estimate is 2,168.3 Gg/yr.
The estimation of CO2 emissions from forestry and land-use change requires the consideration of events over a long period of time. When forests are cleared or agricultural lands abandoned, the biological responses result in "commitments" of fluxes of carbon to or from the atmosphere for many years after the land use change.
The basic calculations focus primarily on forest conversation processes and abandonment of managed lands. The calculations of CO2 removals or emissions of forests have taken into account alterations of areas and aboveground biomass changes due to management of forests. Annual removal of CO2 from atmosphere by Estonian forests is estimated during the inventory year to be 11,346.8 Gg. This figure includes 7,438.3 Gg CO2 due to the accumulation by the total growth increment of managed forests and 3,908.5 Gg CO2 due to the accumulation by abandonment of managed lands over previous 20 years (Table 6).
In the processes of forest management some amount of remains may be removed from the conversion site and used as fuelwood or for other purposes. By- products and wood waste from forest industries are partly used as raw material for fuel. This activity contributes 30 percent of the total burning releases of 2,822.0 Gg of CO2 annually. A portion may be burned on site or converted to slash and decayed to carbon dioxide step by step. The annual rate of soil CO2 emission from forest conversions was estimated at 508.7 Gg CO2. Total CO2 emissions from the forest ecosystem is 3,399.4 Gg CO2. Taking into account emissions and removals of CO2 in forest ecosystems the net CO2 uptake by forest ecosystems in Estonia is estimated at 7,947.3 Gg per year.
Forest management activities may also result in fluxes of other greenhouse and radiatively important gases present in the atmosphere. Open burning associated with forest clearing or other land-use change may cause emissions of non-CO2 trace gases to the atmosphere. Our data show that methane (CH4), carbon monoxide (CO), nitrous oxide (N2O) and oxides of nitrogen (NOx, i.e. NO and NO2) have been emitted in case of open burning associated with forest conversion in Estonia. However, the share of these gases from forestry is not considerable.
Preliminary results for the GHG budget in Estonia in 1990 are given in Table 8. In the industry sector the emissions of GHG decreased from 1990 to 1994 by about 1/3. In the energy sector the emissions will decrease when oil shale using Thermal Power Plants will be modernized and the efficiency of the boilers and flue gas cleaning equipment will be increased (Moetus, 1993; State Energy Dept., 1992; Statistical Office, 1993; Taehtinen, 1992). The emissions from transport are stabilizing as a trend of increasing use of newer cars is occurring. The taxes on old cars are higher and the average salary is continuously increasing.
The CO2 budget in boreal zone trees is positive since more carbon is accumulated than emitted during the respiration and decay. Forest management and industrial use of forest might lead to critical changes in the GHG budget.
In agriculture the emissions are decreasing since the use of fertilizers has considerably decreased when compared to 1990.
For peatlands the peatland loss has been reduced, but new problems arise in connection with land privatization. Some projects have been started to solve these problems and design laws and taxes to protect peatlands.
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