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Rakhmonov K.R., PhD associate professor Land hydrology department National University of Uzbekistan named after Mirzo Ulugbek
Uzbekistan, Tashkent Erlapasov N.B., PhD associate professor
Hydrometeorology and environmental monitoring department National University of Uzbekistan named after Mirzo Ulugbek
Uzbekistan, Tashkent Rapikov B.R.
PhD candidate Land hydrology department National University of Uzbekistan named after Mirzo Ulugbek
Uzbekistan, Tashkent
REPRESENTATIVE CONCENTRATION PATHWAYS (RCP) -IMPACT OF CHANGES IN ATMOSPHERIC GREENHOUSE GAS
CONCENTRATIONS ON THE HYDROLOGICAL REGIME OF THE CHIRCHIK RIVER
Abstract. Today, several climate projections have been developed that represent an increase in the amount of greenhouse gases. These projections serve to model atmospheric chemistry as the first step in developing climate scenarios. One of them is called RCP (Representative Concentration Pathways).
Key words: Climate change, climate projections, climate models, greenhouse gases, Chirchik river, hydrological regime, forecast.
Introduction. Today, there are the following types of RCPs:
1. RCP 2.6 (IMAGE)
2. RCP 4.5 (MiniCAM)
3. RCP 6.0 (AIM)
4. RCP 8.5 (MESSAGE)
RCP 2.6 is a projection developed by the IMAGE modeling team of the Netherlands Environmental Assessment Agency. Based on this projection, greenhouse gas concentrations are assumed to change at very low levels in the future. In particular, the level of exposure to radiation will reach a value of about 3.1 W/m2 in the middle of the 21st century and will decrease to 2.6 W/m2 by 2100.
RCP 4.5 is a projection developed by the MiniCAM modeling team at the Joint Global Change Research Institute (JGCRI) at the Pacific Northwest National Laboratory. This is the stabilization scenario, in which total radiation exposure is stabilized by 2100 by adopting a range of technologies and strategies to reduce greenhouse gas emissions.
RCP 6.0 is a projection developed by the AIM Modeling Group at Japan's National Institute for Environmental Studies (NIES). This is also a stabilization scenario, and after 2100 the radiative effect will be relatively stabilized through actions and measures taken to reduce the amount of greenhouse gases.
RCP 8.5 is a projection developed by the MESSAGE modeling group of the International Institute for Applied Systems Analysis (IIASA) in Austria and the IIASA Integrated Assessment Framework. Based on this projection, the concentration of greenhouse gases will increase at high levels over time.
In turn, the change in the concentration of greenhouse gases in the atmosphere according to the above projections will lead to an increase in the average temperature on the Earth's surface. We can see this in the table below.
№ RCP Increase in average temperature on Earth (year 2100), °C
1 RCP 2.6 (IMAGE) 1,0 (0,9-2,3)
2 RCP 4.5 (MiniCAM) 1,8 (1,7-3,2)
3 RCP 6.0 (AIM) 2,2 (2,0-3,7)
4 RCP 8.5 (MESSAGE) 3,7 (3,2-5,4)
Results and discussion. Carbon dioxide, a product of anthropogenic activity, is added to the natural carbon cycle. Every year, there is a natural cycle of many millions of tons of carbon between the atmosphere, oceans and land cover. The trade-offs in this vast and complex natural system are precisely balanced. During the 10,000 years before the industrialization period, the amount of carbon dioxide in the atmosphere changed by about 10%. But during the last 200 years, that is, since 1800, its amount has increased by 30%. Considering that half of the anthropogenic carbon dioxide emissions are absorbed by the oceans and plants, its amount in the atmosphere increases by 10% every 20 years.
In the table below, we can see the change in carbon dioxide levels up to 2100 under different RCP projections (Table 2)
Table 2
RCP projections of carbon dioxide (CO2) concentrations change to 2100
№ Years RCP 2.6 RCP 4.5 RCP 6.0 RCP 8.5
1 1900 295,800 295,800 295,800 295,800
2 1910 299,700 299,700 299,700 299,700
3 1920 303,025 303,025 303,025 303,025
4 1930 307,225 307,225 307,225 307,225
5 1940 310,375 310,375 310,375 310,375
6 1950 310,750 310,750 310,750 310,750
7 1960 316,273 316,273 316,273 316,273
8 1970 324,985 324,985 324,985 324,985
9 1980 338,360 338,360 338,360 338,360
10 1990 353,855 353,855 353,855 353,855
11 2000 368,865 368,865 368,865 368,865
12 2005 378,813 378,813 378,813 378,813
13 2010 389,285 389,128 389,072 389,324
14 2020 412,068 411,129 409,360 415,780
15 2030 430,783 435,046 428,876 448,835
16 2040 440,222 460,845 450,698 489,435
17 2050 442,700 486,535 477,670 540,543
18 2060 441,673 508,871 510,634 603,520
19 2070 437,481 524,302 549,820 677,078
20 2080 431,617 531,138 594,257 758,182
21 2090 426,005 533,741 635,649 844,805
22 2100 420,895 538,358 669,723 935,874
From the table above, we can see that by 2100, the lowest change in the amount of carbon dioxide is observed in the RCP 2.6 projection, while the highest change is observed in the RCP 8.5 projection. In order to further analyze the obtained results, the data of the table were expressed in a graphic form (Fig. 2).
CO:, ppm
ooooooooooooooooooooo
O —I (N C*> Tl- 'O 00 Ci O —
—I—I—I—I—I—I—I—I—I—'tNtNtNtNtNtNCNtNtNtNCN
Years
Figure 2. Graph of carbon dioxide (CO2) change to 2100 according to RCP
projections
Since the beginning of industrialization, the amount of methane in the atmosphere has increased by 2.5 times. The increase in the amount of greenhouse gases is characterized by the amount of gases released during the use of methane and coal mines and the extraction of natural gas. Today, the contribution of methane emissions to the "increased greenhouse effect" is 20% compared to previous times. The rapid increase in methane levels began later than the rise in carbon dioxide, but its contribution to total emissions is increasing rapidly. It should be noted that the average storage time of methane in the atmosphere is 12
years, while carbon dioxide is more resistant to it, that is, it is stored for a long time.
In the table below we can see the change in the amount of methane gas (CH4) by the year 2100 under different RCP projections (Table 3)
Table 3
Changes in methane (CH4) concentrations up to 2100 under RCP projections
№ Years RCP 2.6 RCP 4.5 RCP 6.0 RCP 8.5
1 1900 879,500 879,500 879,500 879,500
2 1910 923,750 923,750 923,750 923,750
3 1920 977,750 977,750 977,750 977,750
4 1930 1036,250 1036,250 1036,250 1036,250
5 1940 1088,250 1088,250 1088,250 1088,250
6 1950 1147,250 1147,250 1147,250 1147,250
7 1960 1247,000 1247,000 1247,000 1247,000
8 1970 1385,750 1385,750 1385,750 1385,750
9 1980 1547,750 1547,750 1547,750 1547,750
10 1990 1693,630 1693,630 1693,630 1693,630
11 2000 1751,023 1751,023 1751,023 1751,023
12 2005 1753,735 1753,735 1753,735 1753,735
13 2010 1773,128 1767,098 1768,688 1778,675
14 2020 1730,518 1801,434 1785,791 1923,671
15 2030 1600,215 1829,908 1795,924 2132,014
16 2040 1527,098 1841,803 1840,651 2399,245
17 2050 1451,540 1833,094 1894,850 2739,985
18 2060 1365,106 1800,511 1939,391 3076,135
19 2070 1310,651 1744,739 1961,826 3322,341
20 2080 1285,405 1671,829 1940,166 3489,839
21 2090 1268,282 1613,554 1819,142 3638,592
22 2100 1253,628 1576,346 1649,396 3750,685
As can be seen from the table and graphic data, the amount of methane gas in the atmosphere will also have the highest value in the RCP 8.5 projection (3750,685). In the lowest rate of methane gas content is observed in the RCP 2.6 projection, and its absolute amount is equal to 1253,628. In order to analyze the changes in more detail, a graph of the change in the amount of methane gas (CN4) according to the RCP projections until 2100 was drawn (Figure 3).
Figure 3. Graph of changes in methane gas (CH4) to 2100 according to RCP
projections
20% of the greenhouse effect is caused by nitrogen oxides, some gases emitted from industrial enterprises, and ozone. Today, the amount of nitrogen oxide has increased by 16%, which is mainly due to the use of intensive forms of agriculture.
Nitrogen oxides are also projected to change under the RCP projections, and unlike other greenhouse gases, their changes will not be dramatic (Table 4).
Table 4
Changes in nitrogen oxide (N2O) concentrations up to 2100 under RCP
pro ections
№ Years RCP 2.6 RCP 4.5 RCP 6.0 RCP 8.5
1 1900 279,800 279,800 279,800 279,800
2 1910 280,975 280,975 280,975 280,975
3 1920 282,925 282,925 282,925 282,925
4 1930 284,975 284,975 284,975 284,975
5 1940 286,725 286,725 286,725 286,725
6 1950 289,000 289,000 289,000 289,000
7 1960 291,400 291,400 291,400 291,400
8 1970 295,200 295,200 295,200 295,200
9 1980 301,383 301,383 301,383 301,383
10 1990 309,485 309,485 309,485 309,485
11 2000 315,850 315,850 315,850 315,850
12 2005 319,440 319,440 319,440 319,440
13 2010 322,957 322,967 323,071 323,061
14 2020 329,208 329,983 330,202 331,514
15 2030 334,297 337,118 337,159 341,960
16 2040 338,758 344,139 345,339 354,035
17 2050 341,896 350,608 354,592 367,220
18 2060 343,192 356,322 364,714 380,716
19 2070 343,744 361,314 375,515 394,227
20 2080 344,161 365,511 386,465 407,702
21 2090 344,261 369,068 396,859 421,357
22 2100 344,016 372,274 406,265 435,106
Figure 4. Graph of changes in nitrogen oxide (N2O) concentrations to 2100
according to RCP projections
In the next part of the research work, the change in the equivalent concentration of carbon dioxide (CO2) was analyzed. The analysis of changes was carried out based on the following two criteria:
1. CO2 equivalent concentration - taking into account only greenhouse gases accepted under the Kyoto Protocol;
2. CO2 equivalent concentration - taking into account all gases in the atmosphere.
Based on the data in the graphs above, it can be said that if all gases in the atmosphere are taken into account, the change in CO2 equivalent concentration under the RCP 8.5 projection will be drastic. We can see that the changes in the remaining projections are close to each other on both criteria. To compare these changes, the period 1900-2005 was set as the base period for all projections.
Conclusions. CO2, which is considered the most important anthropogenic greenhouse gas worldwide, also accounts for the majority (70 percent) of greenhouse gas emissions in Uzbekistan, mainly due to the energy industry.
However, there are two other main greenhouse gases in Uzbekistan: methane (CH4) and nitrous oxide (N2O). These are 24 and 6 percent of the total amount of greenhouse gases in Uzbekistan, respectively. Agricultural production is the main source of methane and nitrogen oxide emissions. In this case, 90 percent of nitrous oxide is released from fields where nitrogen fertilizer is applied, and 10 percent of methane gas is released from rice cultivation and livestock farming.
Irrigated agriculture is used on almost 8 million hectares of land in five countries located in Central Asia. It is worth noting that irrigation water not only contributes to plant development, but also significantly affects soil, plant, and atmospheric cycles occurring at field and landscape scales in all ecosystems.
The most common type of irrigation in the Aral Sea region is push irrigation. Suppression of fields affects not only hydrological, but also microbiological processes in the soil, carbon and nitrogen cycle to some extent. In wet soil conditions after field irrigation, soil bacteria convert fertilizer nitrate into molecular nitrogen, nitrogen (II) oxide, and nitric oxide (NO). In addition, irrigated rice fields are a major source of atmospheric methane.
In addition, climate change and the greenhouse effect have a significant impact on river water resources. Including:
- the distribution of the amount of flow throughout the year;
- to the variability of the flow;
- to the sources of saturation of the river;
- the type and amount of atmospheric precipitation in the basin, etc.
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