How Econometrics Can Help Us Understand the Effects …
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We focus on soybeans in the main producer and exporter countries: Brazil and
USA, and particularly in Argentina, as an interesting case of mitigation and adaptation
processes due to global and local climate changes.
The chapter is organized as follows. Section “The Effects of Climate Change on
Crop Yields” reviews the empirical literature of the effects of climate change on
crop yields. Section “The Case of Soybeans” describes the case of soybeans. Section
“On the Econometric Modeling of Soybean Yields” discusses different empirical
issues that should be accounted by an accurate econometric model. The last section
concludes.
The Effects of Climate Change on Crop Yields
Different approaches have been followed to study the effects of climate change on
crop yields, many of them based on agronomic analysis. However, results are not
conclusive about the effects of climate change, mainly due to the adaptation and
mitigation strategies in agriculture that have been also implemented to alleviate its
potential negative effects.
The negative effects of climate change are mainly associated to extreme high temperatures which are found to be harmful for crop growth (e.g., Chen et al. 2013). Crop
yield losses on the hottest days drive much of the effect of temperature (Schlenker
and Roberts 2009). In fact, many recent studies found that changes in temperature
are more important than changes in rainfall, at least at the national and regional
levels (Reilly and Schimmelpfennig 2000; Schlenker and Lobell 2010). Furthermore, crops are more sensitive to extremely high temperatures during the phases of
the plant growth cycle (Auffhammer et al. 2012; Welch et al. 2010). Temperature
extremes can be critical for reducing yields, especially if they coincide with the flowering stage of the crop (Wheeler et al. 2000). Burke and Emerick (2016) examine
the effect of long-term changes in climate variables on yields using county-level
data in the USA. Their results indicate that the main crops in the USA—corn and
soybeans—are significantly and negatively affected by long-term changes in extreme
heat temperatures.
Nevertheless, there would be several factors that have reduced the harmful impacts
of climate change: adaptation, trade, the declining share over time of agriculture in
the economy, and carbon fertilization. As stated by Nordhaus (2013, p. 84) “one
important mitigation factor for agriculture is carbon fertilization”. The carbon (or
CO 2 ) fertilization effect is the phenomenon by which the increase of carbon dioxide in the atmosphere increases the rate of photosynthesis in plants. That is, the
largest amount of carbon dioxide (CO 2 ) in the atmosphere, that has resulted from
rising anthropogenic emissions, may have positive effects on the plant’s growth as
they use carbon dioxide during photosynthesis. Carbon fertilization has a greater
effect on plants with C 4 and C 3 photosynthesis systems (such as corn and soybeans,
respectively), which can concentrate carbon dioxide onto reaction sites.
19
We focus on soybeans in the main producer and exporter countries: Brazil and
USA, and particularly in Argentina, as an interesting case of mitigation and adaptation
processes due to global and local climate changes.
The chapter is organized as follows. Section “The Effects of Climate Change on
Crop Yields” reviews the empirical literature of the effects of climate change on
crop yields. Section “The Case of Soybeans” describes the case of soybeans. Section
“On the Econometric Modeling of Soybean Yields” discusses different empirical
issues that should be accounted by an accurate econometric model. The last section
concludes.
The Effects of Climate Change on Crop Yields
Different approaches have been followed to study the effects of climate change on
crop yields, many of them based on agronomic analysis. However, results are not
conclusive about the effects of climate change, mainly due to the adaptation and
mitigation strategies in agriculture that have been also implemented to alleviate its
potential negative effects.
The negative effects of climate change are mainly associated to extreme high temperatures which are found to be harmful for crop growth (e.g., Chen et al. 2013). Crop
yield losses on the hottest days drive much of the effect of temperature (Schlenker
and Roberts 2009). In fact, many recent studies found that changes in temperature
are more important than changes in rainfall, at least at the national and regional
levels (Reilly and Schimmelpfennig 2000; Schlenker and Lobell 2010). Furthermore, crops are more sensitive to extremely high temperatures during the phases of
the plant growth cycle (Auffhammer et al. 2012; Welch et al. 2010). Temperature
extremes can be critical for reducing yields, especially if they coincide with the flowering stage of the crop (Wheeler et al. 2000). Burke and Emerick (2016) examine
the effect of long-term changes in climate variables on yields using county-level
data in the USA. Their results indicate that the main crops in the USA—corn and
soybeans—are significantly and negatively affected by long-term changes in extreme
heat temperatures.
Nevertheless, there would be several factors that have reduced the harmful impacts
of climate change: adaptation, trade, the declining share over time of agriculture in
the economy, and carbon fertilization. As stated by Nordhaus (2013, p. 84) “one
important mitigation factor for agriculture is carbon fertilization”. The carbon (or
CO 2 ) fertilization effect is the phenomenon by which the increase of carbon dioxide in the atmosphere increases the rate of photosynthesis in plants. That is, the
largest amount of carbon dioxide (CO 2 ) in the atmosphere, that has resulted from
rising anthropogenic emissions, may have positive effects on the plant’s growth as
they use carbon dioxide during photosynthesis. Carbon fertilization has a greater
effect on plants with C 4 and C 3 photosynthesis systems (such as corn and soybeans,
respectively), which can concentrate carbon dioxide onto reaction sites.