1. The Great Drought of the 16th Century,
compared to the 1950s
1950s
“megadrought”
Gutzler (2011)
data from treeflow.org

2. The Great Drought of the 20th Century,
compared to today
Annual Water Year Precipitation, ?
Rio Grande Headwaters
Consecutive Years < 16”
(4 yr)
(2 yr)
Upper Rio Grande basin
Consecutive Years < 14”
(6 yr)
2011 (1 yr)
1950
2000
data from WestMap

3. Projected Change NM2 Temperature28
Projected Change NM2 Temperature 2
(°C) 24 20 4
model output
(18-model avg)
A1B-forced, 18-model average -4
1900
2000
2100
A data/model hybrid scenario:
a) : monthly data
b) : sum of 3 terms:
i) climatology
ii) model-average linear trend
iii) interannual anomaly from data exactly 100 years earlier 28
model trend +
historical vblty 24
data 20 4 -4
1900
2000
2100
Gutzler & Robbins (2011) 3

4. Present and Projected Rio Grande Streamflow
3 different
model
projections
(A1B-forced)
Snowpack currently feeds
late spring flood pulses on the
Rio Grande and its tributaries
In a warmer climate:
Earlier snow-fed flood pulse
Reduced total streamflow volume, especially in late spring/early summer
2030: % reduction
2080: % reduction
Hurd and Coonrod (2008) 4

5. Lessons from history and climate modeling
Big droughts happen here … worse than the 1950s
Current drought can’t yet compete with the 1950s
(in terms of consecutive years of dryness)
But warming trends amplify the hydrologic impact of long-term precipitation deficits
… “drought” becomes the new normal
Happy New Year!