all the tea in China
Modeling crop production in a changing climate
Presented by Rebecca Nemec
5th Annual Friedman Fellows Symposium
November 17, 2012
New York City, New York
First, a word about PowerPoint
Source: Greens, Greed and Grain blog by Michael Roberts
Agriculture and Climate Change
MITIGATION
&
ADAPTATION
Trends in Climate in China
• Warming during last 50 years (more in winter than summer)
• More pronounced in minimum than maximum daily temperature
• Increased frequency of short duration heat waves
• Area affected by drought >6.7 million hectares since 2000
• 7-fold increase in frequency of floods since 1950s
Source: Intergovernmental Panel on Climate Change Fourth Assessment Report:
Climate Change 2007. Available online at: http://www.ipcc.ch/.
Global production in 2010
Source: Food and Agriculture Organization of the United Nations, FAOSTAT.
Health benefits of tea
Source: Serafini et al 2011.
Tea Production in China
•
Perennial evergreen tree or shrub
•
Tropical and sub-tropical environments
•
In commercial plantations trimmed to 1 m tall
for easier harvesting. Can grow up to 12m.
•
Elevation: sea level to 2,200 meters
•
Takes three years from planting to first harvest
•
Typical economic life span is 50 to 60 years
•
938mm to 6,000mm of rainfall necessary for
growth
•
In 2012 - 1.6 tons of tea produced on 2.3
million hectares
Source: FAO 2010; DeMatta 2010;
Ahmed and Stepp (Unpublished)
Chinese “tea belt”
Source: Li et al 2011.
Trends in production over time in China
Source: Food and Agriculture Organization of the United Nations, FAOSTAT and Chinese Statistical Yearbooks.
Our research
• Anecdotal evidence from our collaborators’ research in Yunnan Province
(interviews with Chinese tea farmers) that monsoon onset, duration and
precipitation has changed in recent years
• Large body of economic research that
(1) Quantifies impact of climate change on historical production
(2) Estimates future impacts on agriculture production (can measure
both in monetary value)
• Our research purpose is to
(1) Quantify economic impacts of climate change on tea production in
China
(2) Determine which weather factors have the biggest impact on tea
production
• Particular focus on monsoon onset, duration, and precipitation
Draft analytical model
Ypt = Yield (tons/ha) of tea in the p province in year t.
αp = Provincial level fixed-effects - control for unobservable factors that are time invariant but vary across provinces.
λt = Time-fixed effects - changes over time in tea production that are consistent across provinces but vary over time.
Xp = Soil quality factors matrix
• Organic carbon
• Cation exchange capacity
• Base saturation
• Drainage class
• Slope %
• Elevation
W pt = Weather variables matrix
• Minimum temperature and maximum temperature
• Growing degree-days for tea (accounts for heat that tea is exposed to)
• Monsoon onset
• Monsoon duration
• Precipitation during monsoon season
• Precipitation during the dry season (non-monsoon period)
• Solar radiation
Thank you and questions!
References
1. Auffhammer, M., Ramanathan, V., Vincent, J.R. 2012. Climate change, the monsoon
and rice yield in India. Climatic Change 111: 411 – 424.
2. Chinese Agriculture Yearbooks (1984-2009). Published by the Chinese Statistical
Bureau.
3. DeMatta, F. 2010. Ecophysiology of Tropical Tree Crops. Nova Science Publishers,
Hauppauge, New York.
4. Food and Agriculture Organization of the United Nations, FAOSTAT database.
Available online at: http://faostat.fao.org.
5. Greens, Greed and Grain Blog by Michael Roberts. Available online at:
http://greedgreengrains.blogspot.com/.
6. Intergovernmental Panel on Climate Change Fourth Assessment Report: Climate
Change 2007. Available online at: http://www.ipcc.ch/.
7. Li, S., Wu, X., Xue, H, Gu, B., Cheng, H., Zeng, J., Peng, C., Ge, Y., Chang, J. 2011.
Quantifying carbon storage of tea plantations in China. Agriculture, Ecosystems, and
Environment. 390 – 398.
8. Serafini, M., Del Rio, D., Yao, W.N., Bettuzzi, S., Peluso, I. 2011. Herbal Medicine:
Biomolecular and Clinical Aspects. 2nd Edition. Boca Raton, FL. CRC Press.
9. World Bank Data – GDP Deflator for China. Available online at:
http://data.worldbank.org/.