2020-03-14_New_Scientist

14 | New Scientist | 14 March 2020

“I WAS blown away when I first

saw the skull, it’s so well preserved

and so damn weird,” says Jingmai

O’Connor at the Chinese Academy

of Sciences. “I knew it was so rare.”

This birdlike dinosaur was

discovered in northern Myanmar

and has been analysed by O’Connor

and her colleagues. It is 99 million

years old and the smallest dinosaur

ever found from the Mesozoic era.

CT scans revealed that the

creature, named Oculudentavis

or “eye tooth bird”, had bulging

eyes and sharp teeth (Nature, DOI:

10.1038/s41586-020-2068-4).

Its narrow eye sockets would only

have let in limited light, suggesting

it was most active during the day.

The skull measures just

1.4 centimetres across, indicating

it may have been smaller than any

bird living today, but the jaw shape

suggests it had a powerful bite.

“It was probably smaller than the

bee hummingbird,” says O’Connor.  ❚

Palaeontology

SCIENTISTS have warned that

the world must reduce carbon

emissions to net zero sooner

than 2050, after discovering that

tropical forests are removing less

and less CO2 from the atmosphere.

Climate change models predict

that forests in the Amazon and

equatorial and West Africa will

act as a sink for carbon emissions

well into the second half of this

century. But Simon Lewis at the

University of Leeds, UK, and his

colleagues found that the Amazon

could be a net emitter of carbon

in as little as 15 years. “It’s grim, so

grim. It’s the most worrying paper

I’ve written,” says Lewis.

The researchers looked at

ground surveys of 300,000 trees

over 30 years in these regions,

and found that CO2 absorption

in the Amazon has already shrunk

significantly, with equatorial and

West African forests set to follow.

Intact forests across these areas

removed 6 per cent of humanity’s

CO2 emissions in the 2010s, or

around 25 billion tonnes of CO2.

This is down from around 46

billion tonnes, or 17 per cent, in

the 1990s. This change was due to

forests shrinking, the remaining

trees growing less and so absorbing

less CO2, and the huge growth in

carbon emissions from humans.

The researchers used these

observations to model the future

and found that while the Amazon

could become a net source of

carbon emissions by 2035, the

tipping point for equatorial and

West Africa was far enough in the

future that they didn’t project a

date (Nature, doi.org/ggnd46).

In recent years, there have been

calls to cut global emissions to net

zero by 2050 to avoid temperature

rises of more than 1.5°C. Yet this

deadline is based on models that

assume tropical forests will still be

carbon sinks in the second half of

this century. As this no longer

seems likely, Lewis says we will

“need faster and greater cuts to

get to net zero” sooner than 2050.

Stopping deforestation,

which has reached a 10-year high

in Brazil, will also be key, because

disrupted forests are more likely

to dry out and release CO2.

Erika Berengeur at the

University of Oxford says this

analysis provides a good estimate

of tropical forests’ carbon sinks,

but their diminished capability to

absorb CO2 shouldn’t be used as

an excuse to chop them down.

She notes that the study only

focuses on intact forests and that

even though large areas of the

Amazon have been disturbed by

human activities, those parts still

play a vital role in absorbing CO2.  ❚

Climate change

Tropical forests may stop absorbing CO₂

Layal Liverpool

A tiny skull in amber

New dinosaur species identified from 99-million-year-old remains

LIDA XING

News

2035

The year the Amazon could be

a net source of carbon dioxide Adam Vaughan