Transcript Climate Change in the Yaqui Valley - David Battiste, University of

Climate Change in the Yaqui
Valley
David Battisti
University of Washington
1. Climatological Annual Cycle
– Winter vs. Summer
2. Variability(Winter)
– ENSO and Extreme Events
3. Trends and Climate Change
1. (wheat yield and climate)
4. Puzzles
1. The Annual Cycle
• Summer
– Tropical storms,
hurricane debris,
(monsoon)
• Winter
– El Nino/Southern
Oscillation (ENSO)
– Pacific North
American Pattern
– More
2. Interannual Variability
• Winter
Precipitation Anomalies
– El Nino/Southern
Oscillation
(ENSO)
– Pacific North
American Pattern
– More
• Summer
– Not today
• Extreme Events
– Extended
Drought
(Lobell 2003)
ENSO
• ENSO warms offshore
and cools to the east in
the Sierra.
• ENSO brings winter
rainfall to the Yaqui
Valley catchment basin
(r = 0.55)
Precipitation Anomalies
(January-April)
Temperature Anomalies
The
Pacific North American
(PNA) Pattern
• The (+) PNA brings
winter rainfall to the
Yaqui Valley catchment
basin (r=.6).
• The (+) PNA warms
offshore and cools to
the east in the Sierra.
– Yaqui Valley is on a
nodal line for PNA -no signal.
Temperature Anomalies
(January-April)
Precipitaiton Anomalies
(January-April)
The West Pacific (WP)
Pattern
• The mechanisms for the
year-to-year variability
in this ‘new’ pattern of
natural variability are
not known.
• The WP pattern does
bring seasonal
temperature and
precipitation anomalies
to the Yaqui Valley
(warm/dry, cold/wet).
Precipitation Anomalies
(January-April)
Temperature Anomalies
(January-April)
The West Pacific (WP)
Pattern (cont)
• The WP pattern does
bring seasonal
temperature and
precipitation anomalies
to the Yaqui Valley
(warm/dry, cold/wet;
r=0.5/0.7).
• The WP pattern is only
weakly correlated to
SST in the eastern
Pacific.
Temperature Anomalies
(January-April)
Extreme Drought
• The instrument record of Yaqui
Valley basin precipitation has
been extended using tree ring
data.
• Correlation of observed and
reconstructed Nov-April
rainfall is 0.77.
Precipitation Anomalies
(Nov-April)
(Diaz et al. 2002)
Extreme Drought
• The reconstructed precipitation
record extends from 1650 to
1985 AD.
• The average return time for a
drought similar to the present
drought is about 20 years.
• Correlation of observed and
reconstructed Jan-April rainfall
is 0.77.
Precipitation Anomalies
(November-April)
3. Trends and Climate Change
• Annual wheat yield in Yaqui
Valley (1983-2002) is highly
correlated to the Jan-April
average minimum daily
temperature.
Yield
• Is this due to climate or
management?
Temp
• Note: much of the
relationship between
minimum temperature and
yield is interannual (r =0.7)
(Lobell et al. 2003)
Yield and
Climate
Temperature Anomalies
• Increased yield is related to
– Less precipitation (r = 0.8!)
– Reduced minimum
temperatures
– Cold SST immediately
offshore
– Warm SST in the western
Pacific
• The PNA and the WP are
weakly related to yield (r=.31 and .42, respectively)
Precipitation Anomalies
(January-April)
4. Conclusions
• Much of the variability in wintertime precipitation in the
Yaqui Vally catchment is due to patterns of natural climate
variability: ENSO, the PNA and the WP phenomenon.
• The local ocean SST conditions are probably not
influencing Tmin:
– ENSO, remotely forced atmospheric teleconnections (WP) and
variability intrinsic to the atmosphere (PNA) are likely to be
responsible.
• Some of the relationship between yield and climate could
be explained by the collection of natural patterns of
interannual variability:
– The PNA and the WP are weakly related to yield (r =-.31
and .42, respectively)
– Another Pattern is worth checking: the North Pacific pattern.
4. Conclusions
• The trend (20 year) in yield
and minimum temperature
are correlated with the 40
year (warming) trend in the
western Pacific (WP).
• The latter has been argued
in several studies to be due
to increasing greenhouse
gas concentrations (e.g.,
Hoerling et al. 2003)
Warm Pool(WP) Index
4. Conclusions and Puzzles
•
Problems: If the variability and trend
in wheat yield are due to the natural
variability in the PNA and WP (and
the trend in WP), ….
How do drier conditions (r=.7) lead to
lower minimum daily temperatures?
•
Does clearing lead to a greater
diurnal temperature range, and hence
a lower minimum daily temperature,
even
though the daily mean
temperature might be rising?
Summer vs. winter precipitation and
reservoir levels
Forecast Made Sept 2003
ENSO Forecast
Operational forecasts of ENSO
from the Univ. of Washington
Skill: Forecasts for August
Skill: Forecasts from April
Summer Precipitation 2003
North American Monsoon
Experiment
Detail of WP and Mexico
Temperature
4. Conclusions and Puzzles
•
•
Problems: If the variability and trend in wheat yield are due to
the natural variability in the PNA and WP (and the trend in WP),
….
How do drier conditions (r=.7) lead to lower minimum daily
temperatures?
Does clearing lead to a greater diurnal temperature range, and
hence a lower minimum daily temperature, even though the daily
mean temperature might be rising?