The observed warming over the 20th century is unlikely to be entirely natural in origin. There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities.
It has been established that human activity is responsible for the increase of atmospheric greenhouse gas concentrations and their radiative forcing. The atmospheric concentration of the main anthropogenic greenhouse gas carbon dioxide (CO2) since 1750 has increased by 31% and reached 367 ppm. Today's CO2 concentration has not been exceeded during the past 420,000 years. An increasing body of observations gives a collective picture of a warming world and other changes in the climate system. The global average surface temperature has increased over the 20th century by 0.6± 0.2°C.
Vertical zonation, geographical contrasts and mountain surface favor to great diversity of the climatic conditions that can be observed in Tajikistan, which is of big interest for local and regional climate change modeling.
Climate change research considers in details the aspects of climate changes for the period from 1960s to 1990s. The increase of 0.7-1.2°C in the annual mean air temperature was observed in the wide valleys of Tajikistan. In large cities, the growth of near surface temperature was especially significant and reached 1.2-1.9°C that is obviously associated with urbanization. To a lesser degree, the growth of temperature had taken place in mountain areas by 0.1-0.7°C, and only in the mountains of central Tajikistan, Rushan and lower reaches of Zeravshan river there was a small decline in a temperature for 0.1-0.3°C.
The 1990s was the warmest decade during the period of instrumental observations in Tajikistan, and 1997 and 2001 the warmest years.
Models of future climate project that annual mean near surface temperature in Tajikistan will increase within the interval of 1.8-2.9°C by the year 2050. The projected rate of warming is much greater then the observed changes during the 20th century. It is likely that increase of temperature will be essential in the warm period of a year and in some regions will reach 4.9°C.
The tendencies in precipitation in Tajikistan are not uniform. In 1961-1990 in the mountains of Central Tajikistan, as well as in the valleys of southwest and northern Tajikistan, foothills of Turkestan range and Eastern Pamir, a reduction in the amount of annual precipitation of 1-20% is observed. In Karategin-Darvaz and Western Pamir, from the altitude of 1,500 m and higher, and in Western Pamir, the amount of precipitation has increased by 12-18%.
For the period of instrumental observations the most arid years in Tajikistan were 1944 and 2000, when a precipitation deficit of 30-70% was observed all over the territory of the country. The most humid year was 1969, when precipitation was as much as 1.5-2 times above the long-term average.
Due to the complexity of mountain landscape, there is medium and low confidence in precipitation scenarios. According to some models (HadCM2 and others), the increase of annual precipitation to 3-26% is expected by the year 2050. Other models (CCCM and others) project the decrease of precipitation by 3-5% and more.
Changes in snow stock vary in different altitude zones. An increase of snow stock is observed in many foothills and low mountains of the republic. On the contrary, the reduction of snow stock has been observed in many high altitude zones. Recent lack of snow stock in high altitude zones and high temperatures adversely affect stream flows in many rivers.
Projected climate change in global and regional scales will have beneficial and adverse effects on both environmental and socio-economic systems, but the larger the changes and the rate of change in climate, the more the adverse effects predominate. In this regard, adaptation to climate change is of highest importance.
Tajikistan's glaciers in the 20th century lost more than 20 cub.km of ice. Small glaciers (1 sq.km) that comprise 80% of all glaciers and occupy 15% of total ice cover melt intensively. The biggest glacier in Tajikistan is the Fedchenko glacier, the length of which is about 70 km, located in the upper stream of the Muksu river, during the 20th century shrank by almost 1 km; its area decreased by 11 sq.km, and it lost about 2 cub.km of ice. In the period from 1969 to 1986, Skogatch glacier, which is located in Obihingou basin, lost 98.8 million cub.m, which is 8% of the total mass. Many glaciers in Zeravshan basin also retreat.
In the mid-term, the increase of air temperature by 2-3°C will likely accelerate process of glacier retreat. It is very likely that thousands of small glaciers will disappear in Tajikistan. Countrywide, the ice cover will reduce by 20%; the ice volume will decrease by 25-30%. Initially, glacier melting will increase stream flow in some rivers and will partially compensate the decrease of stream flow in other rivers. In the mid- and long-term, a catastrophic reduction of water flow in many rivers is expected.
Water resources in the mid-term will increase in some regions (Western Pamir); in other regions they will deteriorate (Zeravshan, Kafirnigan) due to glacier retreat, change in precipitation pattern and an increase of evaporation. It is likely that scales and consequences of natural disasters will be more spread and destructive due to changes in the global and regional hydrological cycles.
Climate changes have the impacts on the quantity and quality of water resources. The character of river flow is constantly altering that negatively affects local ecology and vulnerable sectors of economy such as irrigation, water supply and hydropower engineering in Tajikistan and Central Asian region.
Changes in vertical zonation of flora and fauna may occur in mountain ecosystems with a rich biodiversity. Mountain pastures and alpine meadows will likely favor, others, such as winter pastures on the contrary will degrade in result of temperature rise and lack of precipitation. It is likely that tugai ecosystem (flood plain) will degrade because of shortage of water resources, increase of temperature, and fire risk. Frequent and long lasting droughts are expected to affect the condition of mesophyllic vegetation and forests. Climate warming will shift phenological parameters of forest vegetation (earlier ripening, fading, blooming, etc.). Biological linkages within ecosystems are expected to alter.
Agriculture in Tajikistan is at particular risk of severe effects of climate change, where apart from other factors, land degradation and desertification are the typical natural processes.
The most damage to agriculture in Tajikistan is occurred in result of such hydro-meteorological phenomena as:
During 1991-2000, annual loses of agricultural gross product from extreme weather events totaled to 1/3 of overall agricultural loss. Long dry periods together with high temperatures in spring and summer seasons lead to the intensification of desertification processes in Southern and Central Tajikistan. Uncontrolled deforestation conditioned by lack of energy resources lead to catastrophic scales of those processes.
In the outlook, water economy will need more water, especially for irrigation, in view of climate warming and increased evaporation. Water needs for irrigation of basic agricultural crops will rise by 20-30% compared to present climate conditions.
Hydropower engineering is relatively stable towards the hydrological cycle fluctuations, however long-term drought and increased suspended solids will negatively affect this economy.
Development of road transport is limited by unfavorable natural-climatic conditions. High temperatures in summer season in valleys and foothills cause infringement of fastness indicators and deformation of road surfaces. Flash floods in spring and mudflows, which spread over the big territories, wash out tens of kilometers of road ballast bed. More than 500 km of roads every year prone to unfavorable natural phenomena, among which climatic factors play essential role.
As a result of climate warming, vector-born and other dangerous diseases, including malaria will spread significantly. Alterations in the hydrological cycle will lead to water shortage and an increase of water temperature in the rivers. This fact will favor to the formation of potential choleric and malaria water reservoirs, especially in lower reaches of the rivers Vakhsh, Kafirnigan, Pyanj, and others. It is very likely that the rise of extreme summer temperatures will lead to higher infant and adult mortality.
In the circumstances, when the climate is changing very rapidly, human adaptation mechanisms are overstrained, and cannot react appropriately, which increases human being's vulnerability. The climate change impact on public health and mortality remains poorly studied both in Tajikistan and in the world. There is a need in future detailed investigations.
Most vulnerable to the climate change is the population in poverty because of absence of necessary resources for coping adverse affects and adaptation.
It should be noted that vulnerability assessment has revealed uncertainties that refer to the lack of scientific knowledge and an inadequate system of observations over the climate change indicators and consequences, including ecosystems, public health, etc.
Last update 03/03/2003