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Near-Term Climate Change Projections
Brad Lyon
International Research Institute for Climate and Society
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Average temperature for boxed region at left
Comparing Two Versions of the Same Temp Dataset
Example #1: Upward Trend in Temp. in Kenyan Highlands?
Points to the need to collaborate with in-region partners, analyze local data
Assessing recent trends in climate presents its own challenges
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Example #2: Downward Trend in Rainfall in the Greater Horn
March-April-May 2009
Mar-Apr-May Seasons
DRY WET
Climate change or
Shorter-term trend?
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Using Historical Data to Estimate Range of Future Climate
Observed Rainfall
25
27
29
31
33
35
37
20
14
20
18
20
22
20
26
20
30
20
34
20
38
20
42
20
46
20
50
20
54
20
58
20
62
20
66
20
70
20
74
20
78
20
82
20
86
20
90
Rainfall(mm
/m
1
Possible Future Rainfall Variability Given Past Behavior
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25
27
29
31
33
35
37
2014
2018
2022
2026
2030
2034
2038
2042
2046
2050
2054
2058
2062
2066
2070
2074
2078
2082
2086
2090
Rainfall(mm/m
1
DRY DRY
WETWET
WET
Using Historical Data to Estimate Range of Future Climate
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25
27
29
31
33
35
37
201
4
201
8
202
2
202
6
203
0
203
4
203
8
204
2
204
6
205
0
205
4
205
8
206
2
206
6
207
0
207
4
207
8
208
2
208
6
209
0
Rainfall(mm/m
1
2
Using Historical Data to Estimate Range of Future Climate
25
27
29
31
33
35
37
39
2014
2018
2022
2026
2030
2034
2038
2042
2046
2050
2054
2058
2062
2066
2070
2074
2078
2082
2086
2090
Rainfall(m
m/m
1
2
3
25
27
29
31
33
35
37
39
201
4
201
8
202
2
202
6
203
0
203
4
203
8
204
2
204
6
205
0
205
4
205
8
206
2
206
6
207
0
207
4
207
8
208
2
208
6
209
0
Rainfall(mm/m
1
2
3
4
5
6
7
8
9
10
11
12
13
14
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25
27
29
31
33
35
37
39
20
14
20
18
20
22
20
26
20
30
20
34
20
38
20
42
20
46
20
50
20
54
20
58
20
62
20
66
20
70
20
74
20
78
20
82
20
86
20
90
Rainfall(mm
/m
1
2
3
4
5
6
7
8
9
10
11
12
13
14
WET DRY
Shortest
Duration (yrs)
10
8
6
4
2
Longest
Average
Using Historical Data to Estimate Range of Future Climate
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Graphic: NOAA
Typical Size of a Model Grid
Cell and Kenyan Topography
Climate Projections Based on Land & Ocean Coupled Models
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Climate Projections Based on Estimates of Future What
Future Greenhouse Gas Concentrations Will Be
This is another source of uncertainty: Which scenario to use?
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OBSERVATIONS MODEL A MODEL B
Models are not Perfect Representations of the Climate System
Annual Average Rainfall (mm/day)
EXAMPLE:Annual Average Rainfall in the Greater Horn
Simply choosing the model grid point nearest the location of interest and using that
raw data to examine possible future changes in climate is NOTa reliable strategy
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It is not Uncommon for Climate Models to be in Disagreement
DRY WET
EXAMPLE: Model Change in Annual Rainfall (2085-2100 minus 1971-2000)
MODEL A MODEL B
mm/day
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21 Models
from IPCC
AR4
Projected PRCP Changes (2080-2099 relative to 1980-1999)
# Models Annual PRCP > 0
% Change in Annual PRCP
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Mitigating the impacts of currentclimate variability is a step towards
adapting to future climate extremes...
EXAMPLE: The 1997-98 El Nino
Percent of Average Rainfall
Oct-Nov-Dec Rainfall 1997
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Summary
