Table 1: Trace gas characteristics and their estimated future impacts on atmospheric warming.
|
Characteristics |
H2O |
CO2 |
CH4 |
N2O |
CFC-11 |
CFC-12 |
O3 |
|
Concentration (ppmv) Pre-1850 1985 A.D. 2030 A.D. |
Variable Variable Variable |
275 345 450 |
0.7 1.7 2.3 |
0.28 0.30 0.38 |
0 0.22 1.1 |
0 0.38 1.8 |
Upto 25% less than now 0.1-1.0 Upto 12.5% more than now |
|
Main IR absorption wavelength (m) |
6.3-8.0 >15 |
4.3 15
|
3.3 7.6 |
4.5, 7.6 8.6 |
9.22 11.22 |
8.68-9.13 10.93
|
4.75 9.6 |
|
Observed (%) increase 1975-1985 |
Variable |
4.6 |
11.0 |
3.5 |
103.0 |
101.0 |
Variable |
|
Approximate lifetime in atmosphere in years |
Variable |
2 |
5-10 |
120 |
65 |
110 |
0.1-0.3 |
|
IR trapping (W m-2) 1985 2050 |
Variable Variable |
50 53 |
1.7 2.5 |
1.3 1.5 |
0.06 0.3 |
0.12 0.6 |
1.3 1.7 |
|
Estimated temperate increase (oK) |
Variable |
0.71 |
0.2-0.25 |
0.10 |
0.24 |
0.12 |
0.06 |
Table 2. Effects of differences in potential climatic changes from doubling of carbon dioxide concentrations in three global GCMs compared to present-day control.
(Data: Schlesinger and Mitchell, 1987)
Parameter |
Season |
Model NCAR |
Model GISS |
Model DFDL |
|
MAXIMUM SURFACE WARMING Latitude average (0C) Northern Hemisphere Southern Hemisphere Geographical LocationNorthern Hemisphere Southern Hemisphere |
DJF JJA
DJF JJA |
7 13
16 18 |
7 7
10 18 |
14 7
18 14 |
|
LATITUDE OF MAXIMUM SURFACE WARMING Northern Hemisphere (0N) Southern Hemisphere (0S) |
DJF JJA |
65 65 |
80 80 |
80 80 |
|
Tropospheric min. Maritime warming (0C) |
Both |
2 |
4 |
4 |
|
Stratospheric max. cooling (0C) |
Both |
-6 |
-3 |
-8 |
|
Precipitation, 300N-300S |
Both |
More to S Less to N |
More to N Less to S |
More to S Less to N |
|
Indian summer monsoon strength Tropical rain rate increase (mm/day) |
JJA
Both |
Same
0.75 |
Lesser
1.25 |
Much more
0 |
|
SOIL MOISTURE CHANGE Australia Africa |
DJF JJA |
Drier Drier except N |
Wetter Wetter except N |
Wetter Dry in E wetter in W |
DJF = December, January, February (Winter in Northern Hemisphere); JJA = June, July, August (Winter in Southern Hemisphere)
Table 3. Estimated average growth and yield changes in C3 species assuming a doubling of CO2 concentration. (SCOPE, 1986)
|
C3-group |
Species |
Immature crop |
Mature crop |
||
|
No. of records |
% increase in biomass |
No. of records |
% increase in biomass |
||
|
Fiber crop
Fruit crop
Grain crop
Leaf crop
Pulses
Root crops
C3 weeds
Trees |
Cotton
Cucumber, eggplant, okra, pepper, tomato
Barley, rice, wheat, sunflower
Cabbage, white clover, fescue, lettuce, chard
Pea, bean, soybean
Sugar beet, radish
Jimson weed, pigweed, ragweed, sicklepod, other weeds
Cottonwood
|
5
15
6
5
18
10
10
14 |
124
40
20
37
43
49
34
26 |
2
12
15
9
13
Nil
Nil
Nil |
104
21
36
19
17
?
?
? |
|
Mean of all C3 plants |
83 |
40+7 |
51 |
26+9* |
|
* = 95% confidence limits.
Note: C3 plants have the highest rate of photosynthesis and can assimilate carbon dioxide better than lower plants.