The Economist - USA (2019-08-03)

16 BriefingThe Amazon The EconomistAugust 3rd 2019

2 The forest’s dry season started to

lengthen in the 1970s; the rains which used

to come in October now come in Novem-

ber. This might have been an effect of de-

forestation; there is some evidence that

water returned to the atmosphere by trees

is particularly important in getting the

rainy season going. The most dramatic ef-

fect of drying seen by scientists, though, is

not a shorter wet season. It is the dispro-

portionate impact of the years in which

rainfall is particularly low.

This century has already seen three

unusually harsh droughts, in 2005, 2010

and 2015. That of 2015 corresponds to an El

Niño event—a see-saw effect in Earth’s cli-

mate whereby a shift in the flow of energy

between the atmosphere and the ocean in

the central Pacific produces a predictable

pattern of climate anomalies all through

the tropics and beyond (see chart 2). The

correlation between El Niño events and

droughts in the Amazon, most notably in

the south-eastern part, predates human ac-

tivities. But those activities may, at a global

level, increase the frequency and intensity

of El Niño events. At the local level they

worsen the damage that droughts do.

The El Niño drought in 2015 was particu-

larly severe. In Nova Xavantina more than a

third of the trees in some of the Marimons’

study plots died in its aftermath. The re-

gion around the city of Santarém, farther

north and deep in the Amazon, saw flames

as tall as buildings tear through the forest,

enveloping the canopy in thick black

smoke that stretched for miles and turned

the sunlight red. For months after the fires

died down, the forest floor smouldered.

Hundred-year-old trees dried out and died.

Nearly four years later, the forest is still

recovering. At one part of the Tapajós Na-

tional Forest reserve, where 580km^2 (11% of

the total area) burned, saplings have shot

up among the ashes of their giant fore-

bears, but it will be years before they form a

canopy. A second round of fires in 2017

burned nearly a quarter of another reserve,

where 75 communities of river-dwellers

make their living fishing and hunting.

Fires are not new to the Amazon, but re-

cently they seem to have been more fre-

quent and intense. This kicks off a vicious

cycle. Dead trees open gaps in the canopy,

allowing more light and wind to reach the

forest floor, which becomes hotter, drier

and more prone to burn again. This year is

expected to be a mild El Niño year, which

means higher temperatures and less rain

for the area around Santarém. Fires could

rage again. If that happens, says Joice Fer-

reira, a biologist at the Brazilian Agricultur-

al Research Corporation, the debris left

over from the previous fires will serve as

fuel for the flames. “After that,” she says,

“there won’t be many trees left.”

Over the past 50 years 17% of the rainfor-

est has been lost, some way from the 40%

tipping-point proposed in 2007. But last

year Mr Nobre and Thomas Lovejoy of

George Mason University, after taking ac-

count of climate change and fire as well as

deforestation, revised the estimate of the

threshold to 20-25%. That is uncomfort-

ably close to today’s figure. Mr Nobre says

the recent droughts and floods could be the

“first flickers” of permanent change. Carlos

Rittl of the Brazilian Climate Observatory, a

consortium of research outfits, expects Mr

Bolsonaro’s tenure to see deforestation

pass 20%. If Mr Lovejoy and Mr Nobre are

right, that could be disastrous—once the

tipping-point is transgressed, much of the

rest of the forest could follow in just a mat-

ter of decades.

To shade the barren wild

Even now, the service that the Amazon pro-

vides the rest of the world as a sink for car-

bon dioxide appears to be declining. Simon

Lewis of University College London, and

colleagues, analysed observations of 321

plots across the Amazon basin. They found

that in primary forests plants absorb, on

average, a third less carbon dioxide than

they did in the 1990s, owing to increasing

tree mortality. In a paper published in 2011

Mr Lewis argued that carbon lost to the at-

mosphere through tree death and fire in

the droughts of 2005 and 2010 might offset

as much as a decade’s worth of carbon-di-

oxide absorption by the forest.

Not everyone is so gloomy. Forests that

are diverse, like the Amazon, are likely to

have drought-resistant species that can fill

the niche left by drought-prone ones with-

out a loss of biomass, points out Kirsten

Thonicke of the Potsdam Institute for Cli-

mate Impact Research, a German think-

tank. Secondary forests store significant

amounts of carbon, though far less than

primary ones. One study found that as a

secondary forest grows, it recovers 1.2%

carbon storage per year, so a 20-year-old

secondary forest would store roughly 25%

of the carbon stored by a primary forest.

There are ways to mitigate the biomass loss

from logging and ranching, by being care-

ful about which trees to cut and reforesting

afterwards. In Paris Brazil pledged not just

to halt illegal deforestation by 2030 but

also to reforest 120,000km^2.

Such attempts at mitigation look in-

creasingly unlikely. In June Mr Bolsonaro

published a decree which indefinitely ex-

tends the 2019 deadline for farmers to be-

gin replanting illegally deforested land.

This not only reduces the chances of refor-

estation. It reinforces the message: the

government will turn a blind eye to more.

Similarly, if his son’s bill were to pass it

would legalise the deforestation of some

1.5m km^2. Clearing that would emit nearly

65bn tonnes of carbon dioxide—equivalent

to Brazil’s emissions over the past 27 years.

In July President Bolsonaro called de-

forestation data “lies” and said he wanted

to review them before they were released to

the public. Hamilton Mourão, the vice-

president, says that other countries’ pro-

fessed concern for the Amazon masks “cov-

etousness” for precious minerals in the re-

gion. Mr Salles, the environment minister,

likes to point out that many rich countries

cut down their own forests but have not

fulfilled promises to pay Brazil not to do

the same. “You can’t give Brazil the onus of

being the world’s lungs without any bene-

fits,” he argues.

The trees stood bare

Mr Salles is right that the countries respon-

sible for the bulk of emissions should com-

pensate Brazil for its role in absorbing

them. In return Brazil must protect, rather

than destroy, the rainforest. In June a trade

deal between the euand Mercosur—Brazil,

Argentina, Paraguay and Uruguay—was

announced at the g20 summit, which in-

cludes a commitment to implement the

Paris climate agreement. It has yet to be ap-

proved; it is also unclear how much it will

sway the president to curb his infrastruc-

ture plans, or indeed his rhetoric.

Concerns about what Brazil’s climate

policies might do to the country’s reputa-

tion could spur local resistance to Mr Bol-

sonaro’s anti-environmental turn. Fears

for the climate itself may yet do more. “We

have no doubt that the forest has a direct ef-

fect on the rain cycle,” says Artemizia

Moita, the sustainability director of a farm-

ing group that has 530km^2 of soyabean and

cattle farms. “If we keep deforesting,” she

asks, “how will we keep producing?” Un-

like other farmers she admits she is wor-

ried about climate change.

For many, any shift in attitudes will al-

ready come too late. Magdalena is an elder-

ly woman who has spent her life as a river-

dweller in one of the rainforest’s reserves.

She used to hunt deer and armadillo to

make her living. Now she treks 13km to buy

beef from a local village. “All the game is

gone,” she laments. 7

Anewabnormal

Amazon,averagesurface-airtemperature*

Deviationfrom1961-90average,°C

Sources:“ChangesinclimateandlanduseovertheAmazon

region:currentandfuturevariabilityandtrends”,

by J.A. Marengo et al. 2018;

INCT for Climate Change Phase 2 *HadCRUT4 data

2

El Niño years Severe droughts

19102000908070601950

0.

0.

0.

0

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