Lamont Doherty Earth Observatory of Columbia University · Lamont Doherty Earth Observatory of...
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Climate variability and change, agriculture and water Richard Seager Lamont Doherty Earth Observatory of Columbia University
Transcript of Lamont Doherty Earth Observatory of Columbia University · Lamont Doherty Earth Observatory of...
Climate variability and change, agriculture and water
Richard Seager Lamont Doherty Earth Observatory of Columbia
UniversityUniversity
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The climate is changing … and burning fossil fuels is the main reason why
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radiatively- forced models
Impact of changing precipitation and temperature on crop production
Challenges to urban water supply
Globalization of local crop production anomalies by international trade
Knock-on effects of climate-induced crop production failures on migration/social stability
Climate variability and change, agriculture and water
Science, Tech & Environment
Mexico City residents brace for water cuts that will leavethem dry for days
January 29, 2016 · 10:45 AM EST
By Monica Campbell
A mother and son fill a container with water collected from a public tap in Tecacalanco, on the outskirts ofMexico City. With a population of more than 21 million, Mexico City and its suburbs place huge demands onthe area's water supply.
Credit: REUTERS/Henry Romero
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Many major cities are struggling to provide a reliable water supply, even without climate change, and create
unrest when augmenting supply
Worries grow as seriousdrought hits São Paulo, BrazilMarguerite Ward | @forwardistWednesday, 1 Jul 2015 | 9:00 AM ET
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The financial hub of one of the world's biggest economies isexperiencing a water crisis so bad that experts say it could affectinvestors globally.
Nelson Almeida | AFP | Getty Images
The Jaguari Jacarei river dam, part of the Cantareira System of dams, is shown in Joanopolis,Brazil.
São Paulo, Brazil, is in the grips of the city's worst drought in the lasthalf-century. The city's main water supply—called the Cantareira system—is running on emergency reserves. Normally at this time of year, thecity's main supply would hold more than 155 billion gallons of water.But that water is all gone, and the government has been forced to tapinto emergency reserves. (Tweet This)
"São Paulo's current drought emergency is both unprecedented andunpredicted," said World Bank Senior Water and Sanitation SpecialistJuliana Garrido.
Before the 2014 drought, the system was supplying about 8,700 gallonsof water a second, according to the World Bank. Today, it's operating at3,563 gallons per second, according to data from Brazil's NationalWater Agency.
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In 2015, drought plus mismanagement, disrupted water supply to residents of the largest city in the
western hemisphere, causing economic losses and damaging public health
Seth et al. (2015)
DJF precip
anomaly
2013/14 2014/15
Sao Paulo precip history
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FIG. 1. Multimodel-median 2070-2099 minus 1975-2004 changes in annual-mean a) precipitation P, b) po-
tential evapotranspiration PET [percentage changes], c) ratio of annual P to annual PET, d) Palmer Drought
Severity Index (PDSI), e) topsoil volumetric water fraction q , f) near-surface relative humidity, g) P�E or
runoff production, and h) net primary productivity (NPP), taken over all CMIP5 models for which these were
available (listed in Table 1.) Stippling indicates at least 80% of the models agree on the sign of the change.
2070-2099 output is from the strong warming experiment (“rcp8.5”) and 1975-2004 output from the historical
experiment.
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Scheff, Seager, Liu, Coats (2017)
Model-projected change in
hydroclimate
Drying on all measures in:
• SW US, Mexico, Central America/Caribbean
• Med/N. Africa/MidEast
• Southern Africa • Chile
P
P-E
CMIP5 multimodel mean 2070-2100 minus 1975-2004
Model projected growing season hydroclimate and
temperature
US corn belt
JJA mean P-E and T, mean and 25th, 75th %ile spread across model runs
JJA mean P-E and T, mean and
Change in JJA P-E, mean, median, spread
Change in monthly JJA Tmax, mean, median, spread
1980 2100
Model projected growing season hydroclimate and
temperature
Europe
JJA mean P-E and T, mean and 25th, 75th %ile spread across model runs
JJA mean P-E and T, mean and
Change in JJA P-E, mean, median, spread
Change in monthly JJA Tmax, mean, median, spread
1980 2100
Model projected growing season hydroclimate and
temperature
eastern China
JJA mean P-E and T, mean and 25th, 75th %ile spread across model runs
JJA mean P-E and T, mean and
Change in JJA P-E, mean, median, spread
Change in monthly JJA Tmax, mean, median, spread
1980 2100
Model projected growing season hydroclimate and
temperature
Southeast South America
JJA mean P-E and T, mean and 25th, 75th %ile spread across model runs
Southeast South America
JJA mean P-E and T, mean and
Change in JJA P-E, mean, median, spread
Change in monthly JJA Tmax, mean, median, spread
1980 2100
In all major grain production regions:
Increasingly (brutally) hot growing seasons
Hot extremes increase by even more than the mean
Drying in Midwest, serious drying in Europe
Bren d’Amour et al. (2016)
Many middle income and poor countries arehighly dependent on grain imports (often of a single grain),
creating vulnerability to remote crop production disruptions
share of total cal
import dependency ratio by grain
Bellemare (2015) found a statistically significant relation between grain
prices and food-related social unrest
In the years preceding the uprising, Syria experienced the worst multiyear drought in the modern era and, according to
tree ring records, in the last 900 years.
tree rings (low pass and annual)instrumental (annual)
Tree ring and instrumental Palmer Drought Severity Index
Cook et al. (2015)
Figure 4: Timeline of the events leading up to the civil uprising that began in March of 2011, and a pie chart of population increase from 2003-2010.
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DROUGHT, CROP FAILURE AND MIGRATION PLAYED A ROLE IN THE EVENTS THAT LED UP TO THE BEGINNING OF THE SYRIAN REVOLT IN 2008
SINCE THE DROUGHT HAD A CLIMATE CHANGE COMPONENT THIS IS LIKELY A CASE OF HUMAN-INDUCED CLIMATE CHANGE CONTRIBUTING TO SOCIAL CONFLICT
Kelley et al. (2015)
Emerging problems
Climate change will exert increasing stress in major grain producing regions synchronously
Natural climate variability (e.g. El Niño-Southern Oscillation) leads to good/bad harvests in different regions at the same
time
How will variability+change evolve in coming decades?
How will the odds for bad harvests in multiple grain baskets at once change? Reasonable to assume it will rise, causing
increased volatility of global food supply
maize production anomaly
wheat production anomaly
El Niño and La Niña life cycles create coherent cycles of pan-Pacific grain production anomalies
Some variations in crop production at the seasonal to interanual timescale are potentially predictable, allowing
anticipation/planning/enhanced food security
Anderson, Seager, Baethgen, Cane (2017)
Conclusions
Climate and environmental change are already stressing agriculture and water supply
Rising heat, changing precipitation, will increase challenge of providing adequate water, with negative consequences for health and the economy
Growing season temperatures in all main grain production regions will rise dangerously high in coming decades, undermining crop production
Historically, lost production is globalized into rising food prices causing social unrest, while local crop failures can lead to migration and/or conflict
Multiple knock-on effects on global economy
Scientific advance can improve prediction and anticipation of weather/climate shocks to ag and food supply, enabling planning
and disaster aversion
