Deforestation in the Amazon is reducing rain in the Brazilian soy...

Climatologists are finding more and more indications that the rainy season starts later and is shorter in Brazil’s soy and corn-growing areas. In a country where only a tenth of its arable land is irrigated, this news is serious.

Research shows, for example, that deforestation in the Amazon region has already resulted in the state of Mato Grosso, Brazil’s largest soy producer, losing almost a month of rain, while the neighboring state of Rondônia has lost about two weeks in value.

The Amazon rainforest recycles the moisture brought in by the Atlantic and creates its own rain. It is known that between 30% and 50% of the rain that falls on the Amazon is due to water carried by the trees themselves. Deforestation interrupts this evapotranspiration cycle – the sum of tree transpiration and land and ocean surface evaporation – and thus reduces precipitation, which researchers refer to as “recycled” rain.

Regions far from the Amazon, such as the Andes or the Rio de la Plata Basin, which stretches across southern Brazil, parts of Argentina, Paraguay, Uruguay and southeastern Bolivia, as well as large cities in southern and southeastern Brazil, depend on the movement of the Amazon from moisture the Amazon.

These rivers are popularly known as “flying rivers”. Felling trees cuts the source of a powerful flow of air. Researchers at the Federal University of Minas Gerais (UFMG) have called this “agro-suicide”.

Deforestation and Rain: New Findings

Researchers at the UFMG Center for Remote Sensing coined the term “agro-suicide” in a new and unpublished article submitted to the journal Communication with nature to illustrate what is already happening in some parts of the Amazon and Midwestern Brazil.

One of the authors, forest engineer and UFMG researcher Argemiro Teixeira, stated in an interview that the group used annual rainfall data that focused on the area known as the “deforestation arc” that bends from the southern to the eastern border of the Brazilian part of the Amazon .

The reasons for protecting the Amazon are not ideological: they are hydrological, climatic, and geochemical

The land was divided into grid cells, with each pixel representing 27 square kilometers. Some of the cells were so severely cut down that the rains were irreversibly affected.

An earlier publication by Teixeira showed that every percentage increase in deforestation in the southern Amazon delays the rainy season by 0.12 to 0.17 days.

“Most worryingly, much of the deforestation arc has already reached this point of no return,” says Teixeira. This means that only regeneration of the forest can restore precipitation to its previous patterns.

Agribusiness: shoot yourself in the foot

Brazil has built its reputation as an agricultural powerhouse as two or even three harvests can be achieved in the same year, with the harvest alternating on the same land.

Since deforestation affects not only the amount of rain but also seasonality, this competitive advantage could be lost. A delay in the rainy season shortens the time available for additional harvests.

In addition to the UFMG study, other recent publications have come to the same conclusion. In September 2019, Marcos Costa from the University of Viçosa led a group published a study in the International Journal of Climatology The rainy season in Mato Grosso had an average of 27 fewer rainy days between 1998 and 2012, a development that can be directly attributed to deforestation in the southern part of the Amazon.

Another article by researchers at the University of Richmond and Dartmouth College, USA, published in nature In June of this year simulated the different effects of vegetation loss in the cerrado and in the eastern and southern Amazon region on crop yields and found that corn production in the cerrado could decrease by 6% to 8%.

Decades of scientific warnings about deforestation and rain

These threats are already known to scientists and representatives of the agricultural industry. Senator and former Agriculture Minister Katia Abreu said she learned about the concept of the flying rivers during her time as head of the National Agriculture Confederation (2008-2011), the sector’s largest lobby group.

“Now everything is turned upside down,” she says, regretting that the government is not protecting the interests of the agribusiness through better environmental protection. “They don’t want to face reality, they flatter half a dozen producers.”

Abreu learned about the rivers from EMBRAPA, the Brazilian state agricultural research company, which pioneered the effects of climate change on food production in Brazil.

Eduardo Assad, an EMBRAPA veteran, published a scientific article in 2013 that looked at the length of dry spells during the rainy season in the South, Southeast and Midwest, and came to the same conclusion as recent studies: global warming and deforestation have caused extremes Drought in the grain-producing region.

Assad’s research found that the length of dry spells within the rainy season has become unpredictable in recent years. Though he adds, “We have spoken [about this] since twenty years!”

However, the first warnings came even earlier, almost 40 years ago.

We need to regenerate our forests and rehabilitate permanent protected areas, because if that doesn’t happen we won’t have rain

Published in an article entitled “Amazon Basin: A System in Equilibrium” science The physicist Eneas Salati of the University of São Paulo warned as early as 1984 about the effects of a possible reduction in rainfall in the Amazon region on the country’s agricultural production.

“Continued large-scale deforestation is likely to lead to increased erosion and water runoff, with initial flooding in the lower Amazon, along with decreased evapotranspiration and ultimately decreased rainfall. Reduced rainfall in the Amazon could increase the tendency to continentality and adversely affect the climate and current agriculture in south-central Brazil. ”

Salati was a pioneer among those studying how Amazon rainfall works in detail. In 1979 he published one of the seminal articles on the region’s moisture recycling system.

In the 1970s, Salati’s work cast a spell over the Peruvian climatologist José Marengo, who was forced to embark on a 25-year career as a researcher in Brazil. Around 2005, Marengo invented the concept of “flying rivers” when he explained the movement of moisture to the aviator Gérard Moss. It was an adaptation of the term “atmospheric rivers” coined by American researchers in the 1990s.

“If you convert all of that moisture flowing over the Amazon into a volume of water, that volume is very similar to that of the Amazon,” says Marengo. “You can feel that moisture, but you can’t see it.”

The concept was a great success in scientific communication. As Marengo relates, congressional officials and senators could easily grasp it. But science wasn’t enough to stop the devastation, even if broken down to be accessible to the general public.

Between 1988 and 2019, an estimated 20% of the Brazilian Amazon was cleared, some of it 796.000 Square kilometers, the equivalent of the land mass of France and Italy combined. Official data show that the rate of deforestation has continued to accelerate in recent years.

Limits and changes

The world has never bought so many agricultural commodities from Brazil as it does today. And this market will continue to grow over the next few decades. Taking into account the scientific knowledge that deforestation affects precipitation in the regions whose production depends on it, the question arises: When does agriculture become unsustainable?

According to Assad from EMBRAPA, soy, corn and cotton are at risk. “Brazil’s production model will reach a limit. The important thing is not to achieve record after record, but to maintain it. We have to regenerate our forests and rehabilitate permanent protected areas, because if this doesn’t happen we won’t have rain. ”“ He says.

Marcello Brito, President of the Brazilian Agribusiness Association (ABAG), agrees. He says productivity gains have been made in recent bumper crops despite increasing systemic risk. “You can make a profit in one region, but another will be badly affected.”

Brito cites the almost constant drought periods in 2020 that affected the states in southern Brazil, which are also important producers of agricultural commodities.

This March, for example, the state of Rio Grande do Sul had just 28 millimeters of rain, a quarter of the historical average, which led farmers to turn to the government for help. The neighboring state of Paraná experienced the worst drought on record in 1997, reaching only two-thirds of the rainfall expected between mid-2019 and early 2020.

Between these states and the Amazon lies the Brazilian Pantanal, the largest wetland in the world, which is currently experiencing the worst drought in its history. Between November 2019 and March 2020, precipitation fell just 350mm, 43% of the expected historical average of 810mm.

Researchers have been reluctant to link the tragedy – which shocked the world with images of charred, dead animals – to deforestation in the Amazon. The occurrence of extreme events, however, corresponds to the decades-long predictions of a more irregular rain distribution.

Brito notes that the historical data on rainfall show “a complete change in the cycle” and therefore production costs have increased. Some companies have been looking for specific, drought-resistant seeds to adapt.

The agricultural sector can be divided into those who believe in science and those who deny it, says Brito. “In my opinion, the majority believe it.”

German Poveda, a Colombian climatologist who is part of the newly created Scientific Panel on the Amazon, argues that the reason for ending deforestation is objectively clear: “The reasons for protecting the Amazon are not ideological: they are hydrological, climatic, geochemical. ”

Changing the development model is the only way out, according to Poveda, which says Amazon countries should invest in an economy based on the sound science of how best to harness their biodiversity.

“This is the only solution between development and environmental protection, our last hope to be economic powers as Amazon countries.”