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Climate and Food Security
Thank you
to the Yaqui Valley and Indonesian Food Security Teams at
Stanford
1.
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4.
Seasonal Climate Forecasts
Natural cycles of drought
Global Warming
Impact of Agriculture on Climate
El Nino/Southern Oscillation (ENSO):
A natural mode of tropical atmosphere/ocean variability
Warm events return every 2-7 years, and tend to peak in NH winter
El Nino - Southern Oscillation (ENSO)
ENSO is a natural pattern of climate variability that is due
to tight coupling between the atmosphere and ocean.
• Small changes in the distribution of sea surface temperature are coordinated
with changes in atmospheric circulation and rainfall patterns;
• The changed rainfall patterns in the tropics force atmospheric circulation
changes that affect climate world-wide.
Temperature Anomalies
Precipitation Anomalies
DJF ENSO Impacts
http://www.cpc.ncep.noaa.gov/
ENSO is Predictable
• ENSO is a true mode of the coupled
atmosphere/ocean system (eg,
patterns of oscillation in a guitar
string)
• The long period (3-4 years) of the
ENSO mode allows for skillful
seasonal climate forecasts (2-4
seasons in advance)
• Presently, empirically based forecast
models are at least as skillful as the
numerical climate models.
Examples of applications of seasonal
forecast (based on ENSO forecasts)
• Yaqui Valley, Mexico
–
Winter precipitation and reservoir
inflow; in-field precipitation; health of
grazing lands
• Indonesia
–
•
Rice yields
Hurricane forecasts
– frequency and intensity
(Atlantic and Pacific)
• Florida
–
•
Frost and citrus crops
Pacific Northwest
–
Snowpack and hydropower, flood
events, recreation, stream flow, etc.
Products: Forecasts of wintertime precipitation in the
Yaqui Valley Catchment
Winter Precipitation (mm)
(winter reservoir inflow is correlated with wintertime precipitation at r =0.87)
ENSO and NDJFMA precipitation
Nino 3.4
•For use with a forecast of ENSO
•The prediction skill of the wintertime state of ENSO
starting in October is > 0.9
ENSO Impacts: Java
Monsoon onset is
delayed during ENSO
warm events.
The delayed monsoon
onset results in reduced
cumulative rainfall
through wet season.
ENSO accounts for 61% of the variance in annual rice
production (1C Nino3.4 <---> 1 Gt rice production)
Climate and Food Security
Thank you
to the Yaqui Valley and Indonesian Food Security Teams at
Stanford
1.
2.
3.
4.
Seasonal Climate Forecasts
Natural cycles of drought
Global Warming
Impact of Agriculture on Climate
Decadal Variability in Sahel Precipitation
Change in Summer Precip
1970-90
Minus
1940-60
• Precipitation in the Sahel is linked
to Sea Surface Temperature
changes (wet is associated with
lower SST in the S. Atlantic and
Indian Oceans)
• Mainly due to natural climate
variability; some part due to 20th
Century changes in CO2 and NH
aerosols.
• Future role of Global Warming
unclear
Correlation of Sahel Summer
Precipitation with SST
Historical Yaqui Reservoir Runoff, 1965-2004
Main Reservoir Yaqui System
8000
7000
6000
5000
4000
3000
1992
2000
1000
1965
0
Fig. From Jose-Luis Minjares
2003
The recent drought in the Yaqui
Valley: how extreme?
•
The reconstructed precipitation
record extends from 1650 to
1985 AD.
•
The average return time for a
drought similar to the most
recent (winter) drought
– six years at 63% of normal
precipitation is about a
century;
– Five years (1998-9 to 2002-3)
at 50% of normal is
unprecedent in 350 yrs.
– For reference, the winter
average precipitation for 19501960 was 79% of normal.
Note: paleo records suggest numerous “megadroughts”
in past 1000 years in the US that are presumably natural
variability.
Climate and Food Security
Thank you
to the Yaqui Valley and Indonesian Food Security Teams at
Stanford
1.
2.
3.
4.
Seasonal Climate Forecasts
Natural cycles of drought
Global Warming
Impact of Agriculture on Climate
Natural Climate Influence
Human Climate Influence
All Climate Influences
We Are We Headed?
21st Century Climate
Change Projections
21st century temperature change
IPCC (www.ipcc.ch)
Projections of Future Climate
Temperature change, 2071-2100 minus 1961-1990
How will climate change due to increasing
greenhouse gases?
Many changes projected by the models are robust and
reliable. Examples of changes that are very likely* over the
next 100 years include:
• the planet will warm, more so in middle and high
latitudes than in the tropics;
• the hydrologic cycle will speed up;
• the area covered by snow and sea ice in winter will
decrease;
• the sea level will rise;
• Increased flooding in some areas.
These changes will be much, much greater than the changes
seen over the past 150 years that have been attributed to
increased greenhouse gases and aerosols.
Trend in Daily Temperature Range
1950-1993
• Night is warming faster than
day.
Impacts of Climate Change on Agriculture
• Increased growing season at high latitudes
• Increased minimum temperature (crop growth and
pest/pathogen effects)
• Continental drying in midlatitudes (?)
• Changes in timing of stream flow in mid and high
latitudes (water availability, etc)
• Changes in heat wave frequency and intensity;
change in frost days.
• Changing patterns of drought.
• CO2 effects on soil BGC, plant pathology; ocean
acidification, etc.
Projections of Future Climate
Precipitation change, 2071-2100 minus 1961-1990
How will climate change affect agriculture in the
tropics and subtropics?
It is highly likely that increasing CO2 will cause large
changes in the patterns and intensity of precipitation
throughout the tropics within the next 50yrs, including:
• Changes in the annual cycle in precipitation
throughout the tropics:
– The spatial and temporal structure of the monsoons will
change in a significant way (eg, making places dry that
are presently wet; changing the duration of the monsoon)
• Changes in ENSO
• Changes in the teleconnection patterns associated with
ENSO
– Changing patterns, duration and intensity of drought
(world-wide).
Unfortunately, the present generation of climate models can
not address these issues. But we are making progress ….
Thank you