The Chinese Academy of Agricultural Sciences (CAAS) and the International Food Policy Research Institute (IFPRI) jointly hosted the International Conference on Climate Change and Food Security (ICCCFS) November 6-8, 2011 in Beijing, China. This conference provided a forum for leading international scientists and young researchers to present their latest research findings, exchange their research ideas, and share their experiences in the field of climate change and food security. The event included technical sessions, poster sessions, and social events. The conference results and recommendations were presented at the global climate talks in Durban, South Africa during an official side event on December 1.

1. IFPRI
Delayed Impact of the North
Atlantic Oscillation on Biosphere
Productivity in Asia
Guiling Wang
Liangzhi You
International Conference on
Climate Change and Food Security
Beijing, November 07, 2011
INTERNATIONAL FOOD POLICY RESEARCH INSTITUTE

2. Outline
NAO
Motivation
Data and Method
Panel Data of Chinese Crop yields
NDVI
Results
Conclusions

3. North Atlantic Oscillation (NAO)
NAO: an oscillation in the gradient of
atmospheric pressure between the
high pressure center near the Azores
and the low pressure center near
Iceland on the Atlantic .
Through its impact on atmospheric
circulation, NAO regulates climate
variability in most of the Northern
Hemisphere.
Positive vs. negative phases of NAO

4. Motivation
Impact on flora and fauna patterns
Although the NAO-related
temperature pattern extends far
eastward into northern Asia, few
documented studies so far
Based on the current notion of the
NAO phenomenon, a time lag longer
than a few months in vegetation
response is neither expected nor easily
explained

5. Our Study
We investigate the impact of NAO on
the productivity of vegetation in Asia
at various time lags
We found that the vegetation response
time in Asia is even longer, at a
surprising 18 months

6. Our Data
Chinese provincial crop yield data from
1979-1997: rice, wheat, maize, sorghum,
millet, potato, and soybean
Satellite-derived monthly Normalized
Difference Vegetation Index (NDVI)-
”Greenness Index”
The monthly NDVI data was derived from
the Advanced Very High Resolution
Radiometer. It spans the period 1982-2000,
and covers the globe with a 1-degree spatial
resolution

7. Our Data (Continued)
PC-based NAO index during the
extended winter (December through
March), provided by NCAR

8. Our Method - Correlation Analysis
A relationship as being significant only if all
of the following four conditions are met:
» the correlation based on raw data is significant
» the correlation based on detrended data is
significant
» detrending the data does not change the sign of
the correlation coefficient
» the above three criteria are met in at least one
contingent area that is larger than the size of
three medium provinces in China

9. Correlation coefficients between winter
NAO index and crop yields

10. Correlation between winter NAO index
and monthly NDVI in subsequent spring

11. Correlation between winter NAO index
and NDVI in the 2nd growing season

12. Correlation between the NAO index and
NDVI

13. Three Characteristics
The time lag between the NAO index and
NDVI is approximately the same as that
between the NAO index and crop yield
The time of significant NAO association
identified from the NDVI data (i.e., July-
October) covers most of the growing season
of the crops for which our crop data
establishes a delayed response to NAO
The region of significant NAO-NDVI
correlation in Asia covers the northern
China where crop yield data suggests a
delayed response of vegetation productivity
to NAO

14. Findings
The crop yield data from China and
the satellite NDVI data are consistent
A significant response of vegetation
productivity in Asia to the NAO
system with a time delay of one and
half years

15. Discussion
The significant response of vegetation
productivity in Asia to NAO with a
delay as long as 1.5 years indicates
that the lasting memory may reside in
some large scale forcing
The role of the Arctic Ocean?

16. Implications
Studies linking carbon dynamics to modes
of atmospheric circulation should take into
account this delayed response in biosphere
carbon assimilation
The timing difference between Europe and
Asia in their ecological responses to NAO
demands separate treatment of these two
continents in many studies
NAO index as a weather-related predictor
for long-range forecast of several grain crop
yields in North Asia

17. The first paper already published in
Geophysical Research Letter

18. New Research
North Atlantic Oscillation as a long-
range forecast of crop yield in North
Asia, in particular North Korea
NSF-funded project(2011-2014): A
Pilot Project on Interactive Climate
and Land Use Predictions

19. Thank You All!