Monitoring the Climate Change Impacts of Urban Agriculture in Rosario, Argentina

Abstract

As the world population in cities has surpassed
that of rural areas, urban and periurban agriculture
(UPA) can become an important strategy, not
only to feed the people, but also to mitigate climate
change. In the city of Rosario, Argentina, with the
support of the RUAF Foundation and the Climate
and Development Knowledge Network (CDKN), a
detailed study is being conducted to monitor the
urban heat island, reduction in the use of food
transportation and preservation and in the impact
of flooding by green infrastructure.

Full text

Urban Agriculture magazine • number 27 • March 2014
50
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Monitoring the Climate Change
Impacts of Urban Agriculture in
Rosario, Argentina
Piacentini R.D., Bracalenti L., Salum G., Zimmerman
E., Lattuca A., Terrile R., Bartolomé S., Vega M.,
Tosello L., Di Leo N., Feldman S., Coronel A.,
As the world population in cities has surpassed
that of rural areas, urban and periurban agricul-
ture (UPA) can become an important strategy, not
only to feed the people, but also to mitigate climate
change. In the city of Rosario, Argentina, with the
support of the RUAF Foundation and the Climate
and Development Knowledge Network (CDKN), a
detailed study is being conducted to monitor the
urban heat island, reduction in the use of food
transportation and preservation and in the impact
of flooding by green infrastructure.
The city’s urban agriculture programme
Municipal support to UPA in the city of Rosario, Argentina,
largely increased after the national crisis of 2001, when
unemployment hit a large number of working families. By
2013 there were 400 gardeners involved in the programme
(280 of them producing food for the market and 120 for
family consumption); 100 unemployed young people are
receiving job training on UPA; 4 garden parks and other
smaller public areas are devoted to vegetable production,
covering a total area of 22 hectares; and 3 urban agro-indus-
tries are producing processed vegetables and cosmetics
from medicinal plants. The total annual production is about
95 tons of vegetables and 5 tons of aromatic plants. The fresh
and processed products are sold by the gardeners on five
street markets in the city.
The Rosario Municipality has designated another 400 hect-
ares in and at the outskirts of the city for expansion of UPA
in the near future. Rosario’s main aims of the UPA programme
were to contribute to food security and income generation.
In 2013 the city expressed interest in also exploring the
potential contributions to climate change adaptation and
mitigation. Supported by RUAF and CDKN and international
research organisations such as WUR-PPO and the University
of Florida, local researchers were trained in impact monitor-
ing and scenario building. The preliminary results of the
research are described below.
Garden park in Rosario, Argentina Photo: Marielle Dubbeling

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The contribution of green areas to reducing the
Urban Heat Island
Temperatures in cities are often higher than in the
surrounding area (this is called the urban heat island
effect). Consequently, cities are an interesting laboratory
for testing different options to decrease the warming intro-
duced by anthropogenic activities (building energy
consumption, transportation, services, etc.). One of these
options is to introduce green coverage, as this can signifi-
cantly reduce the surface temperature of otherwise bare
pavements and built-up spaces. The Rosario team moni-
tored the temperature behaviour of the pavement of a
central square in Rosario, with and without the incidence of
direct solar radiation, in the latter case due to a compact
Pink trumpet vine (Podranea ricasoliana). The measure-
ments were taken with a Minolta Land infrared thermom-
eter. The mean difference of temperatures with and with-
out direct solar radiation during the months of June–July
2013 (around the Southern Hemisphere winter solstice)
was 9.6 (± 2) °C, with the temperature in the plant shadow
being the lowest, as expected. This result demonstrates the
large influence a plant with perennial leaves can have in
reducing pavement (or building) surface temperature.
Reducing such temperatures by applying green coverage
may result in reduced energy use for cooling as well as it
will contribute to reducing ambient temperatures and
thus increasing human comfort levels. It must be pointed
out that this is a result for a particular plant, while we will
extend this study to other time periods and types of trees.
The team also installed temperature-humidity (HOBO)
sensors and data captors in different parts of the city, in
order to record the magnitude of the urban heat island in
different areas and the effect of urban agriculture (gardens
and urban trees) in mitigating temperature differences.
These instruments, which store temperature information
every 15 minutes, are located in tree garden parks (Molino
Blanco, Hogar Español, Facultad de Odontología) and at fixed
points in the city centre with or without tree cover (e.g. under
a tree or exposed to direct sun radiation).
The information recorded during the months of September
to October (Southern Hemisphere spring) show that
average temperatures in the urban gardens are lower than
in the central area, by 2.4 °C. This is particularly interesting
for the garden located near the Facultad de Odontología,
considering that it is located in a highly built-up area and is
surrounded by buildings of about 10 stories high.
In addition to the data-loggers, satellite data was used to get
a detailed description of the spatial distribution of a city and
its surroundings. In Figure 2 we present a multispectral
satellite image Landsat obtained on the 21
st
of June 2013.
Transportation and conservation of food
Food transport, storage and preservation involve significant
energy expenditure, which generally increases with trans-
port distance; use of fossil fuels, storage time and degree of
processing increases. Next to CO2 emissions, use of refrigera-
tion equipment also contributes to emissions of hydrochlo-
rofluorocarbons (HCFCs) and possibly chlorofluorocarbons
(CFCs).
One possible indicator to measure such emissions is the
delay time that each product requires for transportation,
storage and conservation. This corresponds to the time inter-
val between harvest of the product in the place of produc-
tion and delivery to the consumer. Associated with this indi-
cator is the amount of CO2
equivalent (kg CO2 and the other
greenhouse gases) emitted by the whole process of storage
and preservation, according to the needs of each product.
Losses occurring during the process must be included by
incorporating a loss factor.
The use of various means of transportation for the transport
of foods from distant production centres to the city involves
different levels of energy consumption and associated CO2
emissions depending on the type of vehicle, condition, trans-
port distance, type of fuel used and required logistics infra-
structure. Transport systems that require cooling systems
have additional energy consumption and emission of other
highly polluting greenhouse gases (like HCFCs).
Landsat 8/NASA Multispectral Image. The blue band is the
Paraná river and the pink/ reddish colours correspond to the
islands of the Paraná delta. The periurban zone corresponds to
the areas with green color (cultivated area) and brown color
(non- cultivated areas).
Pink trumpet vine (with flowers) placed at the central Montenegro
square in Rosario
Photo: Rosario research team

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A suitable indicator to measure the impact of food transpor-
tation is the number of food kilometres (or food miles) trav-
elled by each product to reach the city. In a more detailed
analysis the amount of CO2 equivalent emitted by the use
and maintenance of roads, warehouses and related services,
like traffic surveillance, should also be considered.
The distribution of food within Rosario can be separated into
a traditional retail circuit and an urban garden retail circuit.
This second distribution circuit ensures a very short time
between harvest of food and its destination (the consumers),
while maintaining a high level of quality and freshness with-
out refrigeration and conservation.
For our research on the reduction of food miles we consid-
ered three products: the first two are squash (including
pumpkin) and string beans, as they are currently produced
in the urban gardens and their production can easily be
increased. The third product is potato, the main vegetable
consumed by the Rosario population. Even if potato is not
produced in the intra-urban gardens, a significant reduction
in CO2 emissions can be achieved if the supply is sourced
from the periurban region and areas near the city with high
horticultural production.
Food transports in Rosario Photo: Marielle Dubbeling
A significant proportion of the potatoes consumed in Rosario
city is currently produced in the Provinces of Mendoza and
Buenos Aires, with a mean distance of about 1000 km from
Rosario. They are moved by truck, usually with a capacity of
20 tons and around 10 % losses. Such transport represents a
fuel consumption of 0.31 litres of fossil fuels per km and a
CO2 output of 3005 ton for each round trip. If this food were
to be produced in the area around Rosario (in the Arroyo Seco
region located at about 30 km), CO2 emissions related to
food transports would be reduced by 97 % per year. Similarly
for the squash/pumpkin, which are imported from Ceres
region about 200 km from Rosario and for the string beans,
produced mainly in the horticultural area of Great Buenos
Aires (about 300 km from Rosario), there would be a reduc-
tion of 92.5 % per year for squash/pumpkin and 95 % CO2 per
year for string beans.
A similar analysis carried out for the other vegetables
consumed in Rosario and other cities in the country would
yield a significant contribution of UPA to reduce food miles
and GHG emissions. Of course, the potential of food growing
in and around cities has to be analysed and production
methods and yield per area should also be included in such
an analysis.
Monitoring the Climate Change Impacts of Urban Agriculture in Rosario, Argentina

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Effects of UPA on run-off and infiltration of
storm water
There are positive effects produced by the increase of green
areas in urban spaces, such as agriculture, forestry and green
roofs on rainfall infiltration and storage capacity. This
contributes to reducing storm water run-off and can offer an
alternative to substantial hardware improvements in urban
drainage systems and infrastructure that are generally diffi-
cult and expensive.
The team introduced a simple method to estimate run-off,
based on a rational equation. The indicator used is the varia-
tion of the run-off coefficient as function of the increase in
green areas. The method we propose is based on the calcula-
tion of the change of the run-off coefficient, relative to the
increase or decrease in UPA surfaces. Different future land
use scenarios were developed, considering the current poli-
cies and land use ordinances, the building patterns in the
city, the area of non-built up land available, etc.
The run-off coefficient is a ratio that indicates the amount of
run-off generated by a watershed, given an average intensity
of storm precipitation. The run-off coefficient varies with
slope, surface condition, vegetation cover and hydrological
soil type. Surfaces that are relatively impervious, like streets
and parking lots, have run-off coefficients approaching one.
Surfaces with vegetation that intercept surface run-off and
those that allow infiltration of rainfall have lower run-off
coefficients (near to 0). All other factors being equal, an area
with a greater slope will have more storm water run-off and
thus a higher run-off coefficient than an area with a lower
slope. Soils that have a high clay content do not allow much
infiltration and thus have relatively high run-off coefficients,
while soils with high sand content have higher infiltration
rates and low run-off coefficients.
Negative values for the variation in run-off (between a hypo-
thetical scenario and the actual situation) at any time period
will indicate a net decrease in run-off (which corresponds to
the reduction of risk of floods) and an increase in infiltration/
References
Brown, M E y Funk C C, Food Security Under Climate Change Vol
319, 580-581, 2008 (available at http://digitalcommons.unl.edu/
nasapub/131).
IPCC (Intergovernmental Panel on Climate Change)/SRRES (Special
report on Renewable sources). Renewable energy sources and
Climate change mitigation (http://srren.ipcc-wg3.de/report).
IPCC (Intergovernmental Panel on Climate Change). Working Group
1: The physical science basis, 2007 (available at: www.ipcc.ch).
IPCC (Intergovernmental Panel on Climate Change). Working Group
1: The physical science basis, 2013 (available at: www.ipcc.ch).
NEF (National Energy Foundation), UK (http://www.nef.org.uk/).
storage of the storm water within a given surface area. It can
be demonstrated that small increases of green areas in
urban systems reduce significantly the risk of flooding. For
example, from historical rainfall data for the city of Rosario,
a 5 %reduction in the run-off coefficient would cause a prob-
ability reduction of 30 % for urban flood risks.
Policy review
Based on these first results a policy proposal on UPA inclu-
sion in watershed management was presented to the
Municipality of Rosario for review. Such policy calls for
increasing the area of green roofs on new and existing build-
ings; integrating UPA in public squares, walks, sides of motor-
ways and railways; and reducing the risk of flooding and
waterlogging caused by paving and building in flooded
areas through UPA strategies, by means of land use ordi-
nances.
More detailed results of the present project will be published
once they become available (later in 2014).
Piacentini R.D.
IFIR, CONICET-National University of Rosario UNR
Bracalenti L. and Salum G.
FAU, UNR
Zimmerman E.
FCEIA, UNR
Lattuca A., Terrile R., Bartolomé S., Vega M., Tosello L.
Municipality of Rosario
Di Leo N., Feldman S., Coronel A.
FCA, UNR
Email corresponding author: ruben.piacentini@gmail.com
A food flow analysis carried
out for vegetables consumed
in Rosario demonstrates
that UPA can significantly
contribute to reduce food
miles and related GHG
emissions