Family farmers need to take measures to deal with climate change, study finds

FGVces study, carried out as part of Greener Belt Project, diagnosed level of vulnerability and exposure to climate threats of small farmers in Upper Tietê River Basin in Sao Paulo State.
24 November 2022
Family farmers need to take measures to deal with climate change, study finds

The Upper Tietê River Basin in the state of Sao Paulo is one of Brazil’s main vegetable producers. However, the region’s high output is threatened by the effects of global climate change, which have altered the frequency and magnitude of extreme weather phenomena such as droughts and floods. As well as jeopardizing the growing and supply of food, this situation also has the potential to negatively affect the livelihoods of hundreds of family farmers, who depend on agriculture as their main or only source of income, according to a study called “Adaptation to Climate Change Among Family Farmers in Sao Paulo’s Green Belt,” carried out by the Center for Sustainability Studies (FGVCes), using resources provided by the Citi Foundation and a partnership with Citi.

The study was part of the Greener Belt Project, which aims to help farming families in Sao Paulo’s Green Belt adapt to climate change.

A 13-month pilot project was conducted around the Cabeceiras River, part of the Upper Tietê River Basin, which encompasses 10 municipalities: Salesópolis, Biritiba-Mirim, Mogi das Cruzes, Suzano, Poá, Itaquaquecetuba, Ferraz de Vasconcelos, Arujá, Guarulhos and Sao Paulo.

Main findings

The researchers performed a climate risk analysis considering three dimensions: vulnerability, exposure and climate threats. (Read more about the methodology below.) Regarding climate threats, the study confirmed an increase in the frequency of extreme events, as observed and reported by family farmers who participated in the pilot project. Below are some highlights of the analysis, which covers the periods from 1980 to 2013 (for maximum temperature, minimum temperature and evapotranspiration) and from 1980 to 2015 (for precipitation):

- Intense rain

Between 1980 and 2015, there was a tendency for extreme rainfall events to become more intense, especially in the central and eastern parts of the municipality of Sao Paulo and also in the municipalities of Poá, Ferraz de Vasconcelos and Suzano.

- Days without rain

Over the same period, there was a considerable increase in dry days per year in virtually the whole of the Upper Tietê River Basin, particularly in the eastern part of the municipality of Sao Paulo, as well as in Poá, Ferraz de Vasconcelos, Suzano and Mogi das Cruzes. In the space of 36 years, the number of rainless days per year rose by between 13 and 20. The combination of more frequent bouts of heavy rain and more dry days, as found between the central part of Sao Paulo and Suzano, indicates the intensification of extreme weather events.

- Maximum and minimum temperatures

The researchers identified consistent increases in both maximum and minimum temperatures across the region. The average maximum temperature went up in all the municipalities in question, especially in the eastern part of the river basin. For example, over the last 33 years, the average maximum temperature increased approximately 2.2°C in the municipality of Salesópolis. Average minimum temperatures exhibited a similar pattern. The frequency of cold days decreased while the proportion of days on which the minimum temperature was below 10°C fell 7.3% in the river basin as a whole. Therefore, the region’s cold days are becoming less cold.

- Extreme temperatures

According to the study, in addition to the increase in average temperatures, the frequency of days with extreme temperatures has also risen. Over the course of 33 years, across the Upper Tietê River Basin, the number of days per year that were hotter than 30°C went up by approximately 12%.

Along with the intensification of extreme weather events, risks were observed in the two other analyzed dimensions.

For example, it was noted that agricultural production is focused on a handful of crops and most of these crops are highly vulnerable to climatic variations and extremes, such as lettuce. Other risks include the inability of irrigation systems to meet the region’s demands, farmers’ high dependence on income from crops, the lack of government programs designed to mitigate potential climate change impacts on agriculture in the region, and urban expansion’s pressure on rural areas.

“Based on our methodology, we concluded that the impacts of climate change do not occur in isolation. Problems may become more or less intense, depending on the vulnerability of people and systems and whether or not they are exposed to events with the potential to cause losses and damage,” explains Samuel de Mello Pinto, a researcher at FGVces.


In order to understand the Upper Tietê River Basin’s susceptibility to climate change, a climate risk analysis was carried out, considering three dimensions: vulnerability, exposure and climate threats.

To understand the “vulnerability” and “exposure” dimensions, the research team analyzed a variety of indicators, including agricultural production characteristics, farmers’ characteristics, the existence of productive organizations such as associations and cooperatives, and different land uses.

Regarding the “climate threats” dimension, four climate variables were evaluated, obtained from a database of daily statistics, interpolated for the whole of Brazil, across a period of 30 years. These four variables were precipitation, maximum temperature, minimum temperature and evapotranspiration. The latter indicator was used to help calculate the region’s water balance.

The Greener Belt Project also carried out field work with 10 groups of farmers. Workshops and a series of engagement and awareness-raising activities were held, during which seven successful experiences of adaptation to climate change by family farmers were presented.

To see the complete study, click here.

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