Mudslide-hit poor are not only Brazilians who should fear deforestation

This month Brazil’s scientific community is mourning the death of Eneas Salati, an agronomist whose ground-breaking studies in hydrology made him the father of the country’s research into its rainfall patterns.

It was Salati’s work since the 1970s that confirmed the vital role the Amazon rainforest plays in regulating Brazil’s climate.

He led the teams which demonstrated how massive “flying rivers” – actually humid low-level jet streams – first form over the Atlantic Ocean before being blown inland on trade winds. They then swell in volume while passing over the rainforest, becoming as rich in water as the continent’s biggest rivers.

This is because the jungle releases vast amounts of vapour into the atmosphere. The professor's team calculated that a single mature tree in the heart of the Amazon can give off up to 300 litres of water a day. When these engorged flying rivers hit the huge wall of the Andes they are deflected south, bringing vital humidity and rainfall to Bolivia, Paraguay and Brazil's central and southeastern states.

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The magnitude of what his teams had discovered meant Salati felt compelled to enter the debate about deforestation: “It is important that we all ask ourselves: if the forest is destroyed through deforestation and global warming, what will happen to the climate in the rest of Brazil?”

Unfortunately Brazil’s new climate chaos now appears to be providing an answer, as huge chunks of the forest have been destroyed while the planet’s temperature has kept ticking up ever since Salati started publishing his research.

Intense downpours

Brazil appears to be becoming a country where, paradoxically, both droughts and severe flooding are ever more frequent. Rain is less reliable and when it does fall, it increasingly comes down in intense downpours that dump record volumes of water in damagingly short time spans.

Bahia, Minas Gerias and São Paulo have all already suffered severe flooding this rainy season and last week it was the turn of Rio de Janeiro state. On Tuesday, the old imperial summer capital of Petrópolis suffered its highest daily rainfall in more than 90 years.

In just four hours, more rain fell on the mountain resort than the expected monthly average for February. The result was the deadliest day yet of the rainy season. Flood water and mudslides crashed down the town’s steep valley walls, destroying whole neighbourhoods. As of Sunday there were 152 people confirmed dead and rescuers are desperately searching for 165 who are still missing.

As well as shock, one can also sense shame in the reaction to Tuesday’s disaster. It is only 11 years since a similar “freak” weather event struck the region, leaving more than 900 people dead. That tragedy prompted solemnly delivered promises to finally tackle the problem of residents living in officially defined “risk areas”. But this repeat a little over a decade later shows those pledges to have been empty and politicians have spent the week scrambling to avoid the blame for their now brutally exposed inertia.

Climate change

Brazilians know why so little has been done – because most of those worst affected by weather events like last week’s are poor. The tragedy in Petrópolis highlights the inadequate housing conditions in which millions of poor Brazilians live and their vulnerability to climate change.

But if complacent politicians and better-off Brazilians more generally believe that they can ride out the implications of continuing to chop down the Amazon in a world of rising temperatures, they have not been paying attention to scientists like Prof Salati.

It was in large part thanks to his research that the idea “without the Amazon there will be no rain” gained traction in Brazil. And “no rain” has the potential to impose huge costs, even on those Brazilians lucky enough not to live in “risk areas”.

Two-thirds of the country’s electricity comes from hydro-electric power stations and concerns over lower water levels in the reservoirs that feed them have become more frequent in recent decades. Also an increasingly compromised Amazon could further disrupt the rains that water Brazil’s agricultural heartlands, with the potential to damage one of the economy’s main motors.

There are major potential implications for the whole of society, not just the poor clinging to hillsides in flood zones, of not acting now to preserve the country’s great forest.