Battisti food&climate1

Climate and Food Security Climate and Food Security Thank you Thank you

to the Yaqui Valley and Indonesian Food Security Teams at to the Yaqui Valley and Indonesian Food Security Teams at StanfordStanford

1.1. Seasonal Climate ForecastsSeasonal Climate Forecasts2.2. Natural cycles of droughtNatural cycles of drought3.3. Global WarmingGlobal Warming4.4. Impact of Agriculture on ClimateImpact 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

Precipitation Anomalies

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

http://www.cpc.ncep.noaa.gov/

DJF ENSO Impacts

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 reservoir inflow is correlated with wintertime precipitation at r =0.87)

•For use with a forecast of ENSO

•The prediction skill of the wintertime state of ENSO starting in October is > 0.9

Nino 3.4

Win

ter

Pre

cipi

tatio

n (m

m) ENSO and NDJFMA precipitation

Monsoon onset is delayed during ENSO

warm events.

The delayed monsoon onset results in reduced

cumulative rainfall through wet season.

ENSO Impacts: Java

ENSO accounts for 61% of the variance in annual rice production (1C Nino3.4 <---> 1 Gt rice production)




Decadal Variability in Sahel Precipitation

• 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

1970-90 Minus

1940-60

Change in Summer Precip

Correlation of Sahel Summer Precipitation with SST

Historical Yaqui Reservoir Runoff, 1965-2004

0

1000

2000

3000

4000

5000

6000

7000

8000

1965

Fig. From Jose-Luis Minjares

1992

2003

Main Reservoir Yaqui System

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 1950-1960 was 79% of normal.

Note: paleo records suggest numerous “megadroughts” in past 1000 years in the US that are presumably natural variability.




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)

Temperature change, 2071-2100 minus 1961-1990

Projections of Future Climate

How will climate change due to increasing greenhouse gases?

• 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.

Many changes projected by the models are robust and reliable. Examples of changes that are very likely* over the next 100 years include:

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 Range1950-1993

• 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.

Precipitation change, 2071-2100 minus 1961-1990

Projections of Future Climate

How will climate change affect agriculture in the tropics and subtropics?

• 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).

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:

Unfortunately, the present generation of climate models can not address these issues. But we are making progress ….

Thank you

Technology

Battisti food&climate1