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SCIENCE science.org 5 NOVEMBER 2021 • VOL 374 ISSUE 6568 679

construction of two planned mainstream

Mekong dams for 10 years. (A month later,

a 60-MW solar farm owned by a Chinese-

Cambodian joint venture was connected to

the national grid.)

And in March 2019, the Bank of China

posted a statement on its website promis-

ing to “very carefully” evaluate the impact

of the $1.68 billion Batang Toru hydropower

project on northern Sumatra in Indonesia,

which it planned to finance. That project

alarmed conservationists because it could

destroy the last remaining habitat of the

Tapanuli orangutan, a frizzy-haired species

considered the world’s rarest ape (Science,

13 September 2019, p. 1064). The bank with-

drew from the project in summer 2020, ac-

cording to government reports. Batang Toru

may go ahead without Chinese support, but

the planned start in 2022 may be delayed

until 2025.

By 2030, megadams “will likely be obso-

lete,” Eyler concludes. But unlike coal-fired

power plants, existing dams are unlikely to

be retired early. The only course of action

“is to replace future dams with solar and

wind,” he says.

ROADS, RAILWAYS, and pipelines—linear

infrastructure—may pose BRI’s biggest

threat to ecological systems and bio-

diversity. These ribbons of development

stretching for hundreds or thousands of

kilometers cause habitat loss and fragmen-

tation, sometimes isolating wildlife popu-

lations in pockets too small to survive.

They can disrupt migratory routes, cause

roadkill, and open pristine areas to illegal

logging and poaching. They have second-

ary impacts as well, such as the construc-

tion of concrete plants and quarries for

limestone, sand, and gravel, causing fur-

ther ecological destruction.

Although many routes are under con-

struction, few have been completed, so

conservationists are still rushing to assess

the threats. A team led by Lechner mapped

planned new BRI roads and railways, along

with upgrades to existing routes, through

Southeast Asia, assessing overlaps with

protected areas, key biodiversity areas, and

the ranges of threatened species. The team

also looked at shipping routes that might

benefit from BRI’s new or expanded ports

throughout the Coral Triangle, a hot spot

for marine biodiversity in the waters sur-

rounding Philippines, Malaysia, Indonesia,

and Papua New Guinea. For each, they as-

sessed proximity to marine protected areas

and reefs, mangroves, and seagrass beds.

They found that land and marine routes

now in planning or under construction

will cut directly through 21 protected areas

and encroach on the 25-kilometer buffer

zones of nearly 30% of the region’s pro-

tected and key biodiversity areas. In Thai-

land, for example, BRI routes encroach

on the Dong Phayayen–Khao Yai Forest

Complex—a UNESCO World Heritage site

home to 800 animal species—and the Khao

Sok National Park–Khlong Saeng Wildlife

Sanctuary, which hosts a relic of the oldest

remaining rainforest in the world. In Laos,

BRI threatens a refuge for endangered

species of cats, deer, gibbons, and bears.

Other BRI routes pose a risk to such iconic

animals as the large-antlered muntjac, the

Malayan tapir, the white-handed gibbon,

the Sumatra serow, and the critically en-

dangered Edwards’s pheasant.

“In Southeast Asia, BRI is increasingly

seen as a threat to the already imperiled

biodiversity,” the team wrote in an August

2020 paper in Biological Conservation.

The same is true elsewhere, according to

Hughes’s Conservation Biology paper. She

looked at 170,126 kilometers of roads and

80,451 kilometers of railways planned to

cross Eurasia and Africa and plotted their

proximity to key biodiversity and pro-

tected areas. “The BRI portends a new and

significant threat to biodiversity globally,”

she concluded.

There are glimmers of hope for mitigat-

ing the devastation, Hughes found. Care-

fully planned forest planting, for example,

could connect forest patches isolated by new

construction or extend ecological corridors.

Such strategies would create new carbon

sinks as well. Identifying animal migra-

tion routes could pinpoint the best places

to build fences to keep animals off high-

ways and forested overpasses so wildlife

can cross them. Seeking to burnish its en-

vironmental credentials, China has recently

advocated steps to protect biodiversity

at home (Science, 15 October, p. 249).

Conservationists hope it will also foster a

network of protected areas and wildlife cor-

ridors across Eurasia to limit BRI’s damage.

But any effective mitigation must rely

on rigorous environmental impact assess-

ments done with international oversight,

conservationists say. BRI projects have

tended to follow the assessment require-

ments of the host countries, which vary

greatly depending on each country’s eco-

nomic development and capacity to study

and protect its biodiversity. (Impact assess-

ments for dams are often limited to effects

in the dam’s immediate vicinity and rarely

consider the cumulative impacts of mul-

tiple dams, a January review in the journal

Water found.) Whether commissioned by

the developers or the host country govern-

ment, environmental impact assessments

are not always made public, and some are

little more than fig leaves, biodiversity advo-

cates say.

Banks could help, Hughes says. “Many

Chinese and Asian banks are starting to

consider green finance and developing

green financial policies,” she notes. They

could require comprehensive impact as-

sessments before opening their coffers. But

time is short. “Many of the routes are under

construction now, with opening dates set

between 2022 and 2024,” Hughes warns.

The window of opportunity for further

greening BRI is closing. j

PHOTO: ANDREW WALMSLEY/ALAMY STOCK PHOTO With reporting by Bian Huihui and Aiya Kuchukova.

A hydropower project on northern Sumatra in Indonesia threatens the endangered Tapanuli orangutan.