Climate Change in Agrarian, Developing Countries David S. Battisti University of Washington

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Climate Change in Agrarian, Developing Countries
David S. Battisti University of Washington

• A case study Climate variability and climate
  change in Africa over the 20th Century
• Projections of climate at the end of the 21st
  Century
• Regions where Climate Change will likely create
  stress
• A case study the Sahel

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Climate Change in Agrarian, Developing Countries

• A case study Climate variability and climate
  change in Africa over the 20th Century
• Climatology and people at risk
• Long term drying trend in the Sahel
• Projections of climate at the end of the 21st
  Century
• Regions where Climate Change will likely create
  stress
• A case study the Sahel

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Annual Mean Precipitation
Regions where short term deficits lead to
agricultural stresses droughts and floods
Desert (30cm/yr)
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Seasonal Mean Precipitation
Growing Season
Jan - Mar
July - Sept
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Semi-arid regions are typically regions of large
climate variability
/- 20 of annual rainfall
For reference, the Dust Bowl is the US was a 8
annual precipitation deficit for seven years.
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Decadal Variability in Sahel Precipitation

• Precipitation in the Sahel is linked to Sea
  Surface Temperature changes (wetter is associated
  with lower SST in the S. Atlantic and Indian
  Oceans)
• Atmospheric models reproduce the interannual
  variability and the drying trend when forced by
  observed SSTs
• Soil moisture feedbacks amplify the SST forced
  precipitation anomalies
• Land use change does not contribute to
  significantly to the drying trend in the Sahel

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The 1950-1990 drying trend in the Sahel
Sahel JJA precipitation

• Global Climate models (AR4) forced over the 20th
  Century with the observed CO2 and aerosol
  distribution simulate a drying trend in the Sahel
• 18 of 19 models examined produce a drying trend
  
• About half of the 1950-1990 drying trend is due
  to increasing CO2 and aerosols from fossil fuel
  burning
• CO2 rich get richer, and so Sahel looses
• Aerosols more emitted in NH than SH, so more
  cooling in the N. Atlantic than the S.
  Atlantic/Indian Ocean

1975-1999 minus 20th Century Ave. 2 std of
simulated 25yr ave variability
Obs
-5
0
-10
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Climate Change in Agrarian, Developing Countries

• A case study Climate variability and climate
  change in Africa over the 20th Century
• Projections of climate at the end of the 21st
  Century (from IPCC 2007)
• Focus on those changes that are very likely
  (i.e., those that are either deemed to have a
  greater than 90 chance to occur based on
  quantitative analysis or an elicitation of the
  expert views)
• Regions where Climate Change will likely create
  stress
• A case study the Sahel

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Emission Scenarios
A2
A1B
B1
Emission Scenarios are created for all the major
anthropogenic greenhouse gases and for aerosols
(due to burning of fossil fuels and biomass)
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A2
A1B
B1
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Global Annual Average Surface Temperature
Referenced to the 1980-1999 Average
Temperature Solid lines average of all models
used. Number of models used varies shaded area
is the standard deviation of the models
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Projected Annual Average Surface Temperature
Change 2080-2099 minus 1980-1999
Average of 21 climate models forced by Scenario
A1B. Multiply by 1.2 for A2 and 0.7 for B1
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Extreme Seasonal Temperatures(from NCEP
reanalysis 1948-2006)
JJA
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Projected Annual Average Precipitation
2080-2099 minus 1980-1999
Scenario A1B
There is a robust drying of the subtropics,
20-35NS.
Stippling is where the multimodel average change
exceeds the standard deviation of the models
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Projected Soil Moisture Change 2080-2099
minus 1980-1999
Scenario A1B
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Projected Hydrologic Changes 2080-2099 minus
1980-1999
Scenario A1B
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Climate Change in Agrarian, Developing Countries

• A case study Climate variability and climate
  change in Africa over the 20th Century
• Projections of climate at the end of the 21st
  Century
• Regions where Climate Change will likely create
  stress
• A case study the Sahel

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Projected Changes in Africa 2080-2099 minus
1980-1999
All 21 models project a warming throughout the
continent. The average across all models shows an
increase of 2.5C in wet coastal areas to more
than 4C in the desert regions.
Scenario A1B
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Projected Changes in Africa 2080-2099 minus
1980-1999
Drying in Northern Southern Africa projected by
more than 16 of 21 models 10-15 of annual mean
in S. Africa 20-30 in N. Africa (regions that
are marginal for agriculture today). About 20
wetter in E. Africa The models diverge for the
Sahel half the models show drying
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Central Asia 20th Century Climatology
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The recent 1998-2001 drought in Central Asia
30 annual mean precip deficit
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Precip Anomaly (mm/month)
0
- 20
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The recent 1998-2001 drought in Central Asia

• Iran 80 of livestock lost
• 35 - 75 reduction in wheat barley
• Afghanistan 40 of livestock lost
• Pakistan 50 of livestock lost
• Tajikistan 50 of grain crop lost

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Projected Changes in Central Asia 2080-2099
minus 1980-1999
Drying in Central Asia and Southern Europe ( 10
- 25 of annual mean precip)
Scenario A1B
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Climate Change in Agrarian, Developing Countries

• A case study Climate variability and climate
  change in Africa over the 20th Century
• Projections of climate at the end of the 21st
  Century
• Regions where Climate Change will likely create
  stress
• A case study the Sahel

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Projected Sahel precipitation (JAS)
MIROC3.2
Simulated in two climate models (Emission
Scenario A1B)
Fraction of 20th Century annual averaged
precipitation
CM2.1
Lu and Held (2006)
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Summary
At the end of this Century (2070 - 2100), the
climate will be very different from the present
climate

• Everywhere it will be warmer
• In most places, the seasonally averaged
  temperature will exceed the top 5 of the warmest
  years in the past century.
• In many places (e.g., the tropics and
  subtropics), the seasonally averaged temperature
  will exceed the warmest year on record.
• Impacts reduced yields, impact on disease
  transmission rates, loss of glaciers (water
  availability and timing)

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Summary (cont)

• In general, countries in the subtropics will
  experience large changes in precipitation by the
  end of the 21st Century
• Typically a 10 - 20 reduction in annual mean
  precipitation
• Increased frequency, duration and intensity of
  drought in subtropics and midlatitudes
• Many of these regions are presently marginal for
  agriculture (precip limited)
• Other climate changes of concern to agriculture
• Sea level rise about 35cm by 2100
• Increase in flooding in midlatitudes and tropics
  (increase intensity of precipitation on drier
  soils)
• In wet tropical places, increases in temperature
  and precipitation should change patterns of
  disease and pests

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Projected Changes in the Caribbean 2080-2099
minus 1980-1999
Drier in the Caribbean by 10-30, depending on
the season (projected by 17 of 21 models)
Drier throughout Central America (5-15 in the
annual mean not shown)
Scenario A1B
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Africa and Short term Climate Prediction

• El Nino/Southern Oscillation (ENSO) is a
  phenomenon that is intrinsic to the climate
  system
• ENSO causes precipitation anomalies across Africa
• regional and seasonal dependence
• greatest impact during the growing season
• likely impacts disease transmission (malaria,
  cholera)
• ENSO -- and therefore the ENSO-related climate
  anomalies in Africa -- are predictable several
  seasons in advance.

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El Nino/Southern Oscillation (ENSO)
Warm events return every 2-7 years, and tend to
peak in winter
Warm Event (El Nino)
Cold Event (La Nina)
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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 patters.
• The changed rainfall patterns in the tropics
  force atmospheric circulation changes that affect
  climate world-wide.

Temperature Anomalies
Regions of active physics
Precipitation Anomalies
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ENSO is Predictable
Skill of ENSO Forecasts 1965-1993

• ENSO is a true mode of the coupled
  atmosphere/ocean system (e.g., 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)
• Skill depends on start month

Model Forecast
Persistence
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Examples of Applications of Seasonal Forecast
(based on ENSO)

• Yaqui Valley - Mexico
• Winter precipitation and reservoir inflow
  potentially in-field precipitation health of
  grazing lands
• Indonesia
• Rice production
• Hurricane Forecasts
• Frequency and intensity (Atlantic and Pacific)
• Florida
• Frost and citrus crops
• Pacific Northwest
• Snow pack and hydropower, flood events,
  recreation, stream flow, etc.

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ENSO forced precipitation anomalies over Africa
Correlations of /- 0.35 are significant at 99

• Predictable anomalies are during the growing
  seasons
• Using Atlantic SST, summer precipitation in the
  Gulf of Guinea is predictable one season in
  advance (r 0.6-0.7)

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The 1950-1990 drying trend in the Sahel
Sahel JAS precipitation

• Global Climate models(AR4) forced over the 20th
  Century with the observed CO2 and aerosols
  distribution reproduce the observed drying trend
  in the Sahel
• 18 of 19 models examined reproduce the drying
  trend
• About half of the 20th Century drying trend is
  due to increasing CO2 and aerosols from fossil
  fuel burning
• CO2 rich get richer, and so Sahel looses
• Aerosols more emitted in NH than SH, so more
  cooling in the N. Atlantic than the S.
  Atlantic/Indian Ocean

Observed Simulated (CM2.0) 1 std of ensemble AMIP
results