Brazil may be successfully cutting its dependence on fossil fuels through the use of bioethanol, but the sugar plantations that fuel the bioethanol industry are causing regional climate effects.
Brazil is the second largest global producer and consumer of bioethanol and this has led to a boom in sugarcane production. To meet the demand, large swaths of Brazilian land are being converted into sugar plantations and this could have direct consequences on the country’s climate by changing the landscape’s physical properties.
According to a team of researchers from Arizona State University, Stanford University and the Carnegie Institution for Science, the anticipated conversion to sugarcane plantations could lead to a 1degree Celsius decrease in temperature during the growing season and a 1 degree Celsius increase after harvest.
“When averaged over the entire year, there appears to be little effect on temperature,” said Matei Georgescu, an assistant professor at A.S.U.’s School of Geographical Sciences and Urban Planning.
“However, the temperature fluctuation between the peak of the growing season, when cooling occurs relative to the prior landscape, and crop harvest, when warming occurs compared to the previous landscape, of about 2 degrees Celsius is considerable,” he said.
Using multi-year regional climate model simulations, the researchers calculated the potential for local changes in temperature and precipitation patterns.
As sugarcane has a higher albedo or reflectivity compared to existing vegetation and the fact that the crop will undergo an annual harvest while the surrounding vegetation does not, sugar plantations will lead to a strong seasonal temperature fluctuation.
Sugarcane harvest could also lead to a net annual drop in evapotranspiration or transfer of water from the land to the atmosphere.
“When harvest occurs, the plant’s ability to transfer water from its extensive root system to the atmosphere is reduced,” explained Mr. Georgescu.
“As the crop matures during the grooving season, evapotranspiration is once again brought back to levels prior to sugarcane conversion. Overall, we find the annually averaged evapotranspiration reduction is about 0.3 millimeters per day,” he added.
Such conditions could cause a reduction in regional precipitation, though no such decrease was found to be statistically significant in the modeling study.
“There is much more uncertainty in regards to precipitation and more work is required in this area,” concluded Mr. Georgescu.
Based on new laws and trade agreements, Brazil’s production of sugarcane-derived ethanol is expected to rise tenfold over the next decade, with considerable land – such as the country’s native tropical savannas or cerrado lands – being converted for growing sugarcane.