The Impact of Climate Change on the Climatic Parameters in Tuyserkan Catchment Using General Circulation Models

Introduction Climate change has a huge impact on all aspects of human life. Some of its impacts can be reduction in the surface and ground water resources of the country, changing the amount, timing, and type of precipitation, and influencing water quality. It can also lead to the increased droughts, increased demand for water, changes in the management of water resources, sea level rise and its complications, and extreme maximum and minimum temperatures. The aim of the present study was to evaluate the impact of the climate change on rainfall and minimum and maximum temperatures using 15 atmospheric general circulation models under two scenarios, including A1B and B1, between the years 2011-2039.
Methodology For this purpose, through the use of beta statistical distribution of rainfall changes and based on the probability of 20, 50 and 80%, the minimum and maximum temperatures, were calculated from 15 general circulation models.
Standard errors, absolute errors, and Nash-Sutcliff coefficients were determined for simulated data on the base and the upcoming periods. Next, of the 15 climatic models, the minimum temperature changes (ΔTmin), the maximum temperature changes (ΔTmax), and rainfall variation ratios (ΔP) for A1B and B1 scenarios for 12 months were extracted from the Lars model. The introduction of the climatic scenarios in the family scenarios of the A1 group, a rapidly growing economy and the growth of the population that will peak in the mid-21st century and decline thereafter introduces new and more efficient technologies. In this family, economic issues are more emphasized and opinions are rather global rather than regional. Three different subgroups for group A1 are based on the type of technology used in the 21st century, the intensification of the use of the fossil fuels (A1FI), the use of non-phosphate energy sources (A1T), and the use of fossil and non-fossil sources in a balanced manner (A1B).
Results and discussion The results showed that, with the probability of 20 to 80% and under both A1B and B1 scenarios, the minimum and maximum temperatures are rising and the rain is falling. In addition, the increase in the minimum and maximum temperatures under A1B was more than that of the B1 scenario, but the reduction in the precipitation under B1 was more than A1B. The results also showed 19 to 22% decrease in precipitation, minimum temperature of 13 to 20%, and a maximum temperature of 2.4 to 6.4% compared to the baseline of the Tuyserkan catchment.
In Table 1, the percentage change in climatic parameters under the influences of A1B and B1 scenarios and in relation to the base curriculum is presented.
Under A1B scenario, and with the probability of the occurrence of 80%, there is 19.1% decrease in precipitation, 4.6% increase in maximum temperature, and 20% increase in minimum temperature in future periods. In addition, under B1 scenario and with the probability of occurrence of 80%, there is 22% decrease in precipitation, 13% increase in minimum temperature, and 4.2% increase in maximum temperature.
Table (1) Assessment of the percentage change in climate parameters relative to the base curve
Scenarios
Probability of occurrence
Precipitation (%)
T_max (%)
T_min(%)
A1B
20
-3.8
1
7.2
50
-13.7
2.8
14.5
80
-19.7
4.6
20
B1
20
1.5
-0.9
7
50
-20
1.5
7.7
80
-22
4.2
13
Conclusion Generally, it can be argued that the climate change in future periods will increase the minimum and maximum temperatures and reduce the rainfall in Tuyserkan Plain. Consequently, these changes in temperature and precipitation will affect plain water resources. The most important of change is the change in the seasonal precipitation pattern and temperature rise in cold seasons. These changes will also have a significant impact on the region's cropping pattern, as the dryland cultivation is limited, due to the reduced rainfall, and its time will vary with time variations.