The Washington Post - USA (2021-11-11)

THURSDAY, NOVEMBER 11 , 2021. THE WASHINGTON POST EZ RE A

COP

BY ADAM TAYLOR

AND HARRY STEVENS

How much warming can the
world bear?
That question is one of the
fundamental issues in dispute at
the ongoing U.N. climate change
summit, known as COP26, in
Glasgow, Scotland.
Here’s what different levels of
warming would look like, and
how global temperature targets
have been set.
Six years ago, when countries
came together in Paris for the
COP21 summit, at w hich the Paris
climate accord was shaped, they
committed to limit the global
average temperature rise to well
below 2 degrees Celsius (3.6 de-
grees Fahrenheit) above prein-
dustrial levels. However, while
the 2015 agreement set 2C as the
minimum, it included language
that suggested countries should
push for a more ambitious goal:
1.5C.
A preliminary draft of the
COP 26 agreement released
Wednesday “reaffirms” the Paris
agreement’s goal: limiting warm-
ing to well below 2C and pursuing
a target of 1.5C. But it does not
commit to meeting the 1.5C
threshold.
The difference between the
two targets may seem small, but
they represent vastly different
levels of effort for countries seek-
ing to limit their carbon foot-
prints, and strikingly divergent
outcomes for the planet.
Some experts doubt that 1.5C
remains achievable. Limiting
warming to 1.5C “will be very
difficult,” Microsoft founder and
philanthropist Bill Gates told
U.K. lawmaker Jeremy Hunt in a
conversation hosted by the think
tank Policy Exchange last week.
Evidence shows that the two
targets also represent different
scenarios for the climate’s impact

on human life. A study released

Tuesday by the U.K. Met Office,

Britain’s national weather serv-

ice, found that 1 billion people

could face heat stress, a potential-

ly fatal combination of heat and

humidity, if temperatures rise by

2C.

“The higher the level of warm-

ing, the more severe and wide-

spread the risks to people’s lives,

but it is still possible to avoid

these higher risks if we act now,”

said Richard Betts, one of the

leaders of the project.

How did the world agree

upon a 2C target?

When world leaders came to-

gether in Paris in 2015, they were

looking to reverse a long period of

international inaction after the

widely perceived failures of the

1992 Kyoto Protocol and the 2009

Copenhagen Accord.

The latter had included non-

binding language that referenced

“the scientific view that the in-

crease in global temperature

should be below 2 degrees Cel-

sius.”

Nearly 200 countries signed

onto the agreement in Paris,

which was adopted in 2015 and

took effect in 2016. Under the

accord, countries would set their

own emission reduction targets

and plans to reach those targets,

but agreed to the long-term tem-

perature goal to limit “the in-

crease in the global average tem-

perature to well below 2C above

preindustrial levels.”

Countries would also pursue

“efforts to limit the temperature

increase to 1.5C above preindus-

trial levels, recognizing that this

would significantly reduce the

risks and impacts of climate

change,” according to the text.

The two targets, one firm and

one aspirational, represented a

fierce policy debate. Developing

countries had been pushing to set

a rise of 1.5C as a target for years.

Small island nations were often

the most vocal in their support,

pointing to the existential threat

they faced.

Around the world, many ad-

opted the slogan “1.5 to stay

alive.”

Has there been a movement

toward a 1.5C target?

The Paris agreement repre-

sented a significant shift. More

than 100 countries expressed

support for a target of 1.5C, in-

cluding for the first time some

major emitters. Notably, the Unit-

ed States got on board, joining a

group called the “High Ambition

Coalition” founded by the Mar-

shall Islands in 2014.

Scientific pressure played a

role in the change. In a paper

published during COP21, Nature

Geoscience stated that “no scien-

tific assessment has clearly justi-

fied or defended the 2° C target as

a safe level of warming, and

indeed, this is not a problem that

science alone can address.”

But there remained some skep-

ticism, with oil and gas producing

Saudi Arabia among the coun-

tries pushing back on the more

ambitious targets. Some officials

argued that countries should

keep to the less ambitious target

so that countries were not set up

for failure.

Former president Donald

Trump pulled the United States

out of the Paris agreement and

promoted the use of fossil fuels.

But, under President Biden the

United States has not only re-

joined that agreement but also

the group of nations that say that

1.5C should be the standard.

However, the U.S. leader has

also privately questioned wheth-

er even the 2C goal is attainable if

top emitters do not stick to their

pledges. And while the draft re-

leased from COP26 on Wednes-

day did include new terms, it did

not set 1.5C as a target.

What does the science say

about the difference between

1.5C and 2C warming?

The Intergovernmental Panel

on Climate Change (IPCC), a U.N.

body responsible for assessing

the scientific research on climate

change, has warned that even an

increase of 1.5C of global warm-

ing would result in significant

differences, with increased heat

waves and short cold seasons.

At 2C, however, the changes

will be more profound. “With

every additional increment of

global warming, changes in ex-

tremes continue to become larg-

er,” the IPCC wrote in a report

released earlier this year that

evaluated more than 14,000 pa-

pers.

The IPCC has found that an

extreme heat event that would

have occurred once per decade in

a climate without human influ-

ence, would happen 4.1 times a

decade at 1.5C of warming. It

would occur 5.6 times at 2C.

Other events such as heavy pre-

cipitation or drought would also

increase.

The IPCC also noted that it was

very likely that the relative sea

level will continue to rise

throughout the 21st century and

beyond, and the level it rises will

be affected significantly by the

level of climate change. If temper-

atures are confined to an increase

of 1.5C, over the next 2000 years

sea levels could rise by as much as

10 feet, but it could be double that

if temperatures grow by 2C, the

IPCC research found, and poten-

tially worse if ice sheets in Ant-

arctica become destabilized.

Individual papers have spelled

out similar scenarios, though

they also show that increases of

over 2C could be far worse. The

Met Office study released on

Tuesday found that while a 2C

increase would result in the num-

ber of people living in areas

affected by extreme heat stress

rising from 68 million today to 1

billion, a 4C rise could see nearly

half of the world’s population

living in those areas.

What are we at now?

A Washington Post analysis of

multiple data sets has found that

Earth has already warmed more

than 1 degree Celsius on average

over the past century. Some plac-

es may already have seen rises of

2C.

In their latest report, the IPCC

estimated that under the current

scenario, the world would likely

hit the 1.5C threshold by 2040.

Under the most optimistic sce-

nario presented in the report,

global temperatures would reach

1.5C by the middle of the century

and then drop back down as

emissions were cut further, po-

tentially avoiding some of the

worst outcomes.

Under the worst scenario en-

visaged by the IPCC, the best

estimate was that the world will

likely see a rise of 4.4C by the end

of the century — with an extreme

impact on life on Earth.

[email protected]

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H ow g lobal climate targets are set and what they mean

DAVID GOLDMAN/ASSOCIATED PRESS

The difference between the two targets may seem small, but they represent vastly different levels of

effort for countries seeking to limit carbon footprints, and strikingly divergent outcomes for the planet.

Leaders at COP26 weigh

the outcomes of climate

warming by 1.5C or 2C

Friday, November 12 at 9:00 a.m.

Washington Post Live’s “First Look” offers a smart, inside take on the day’s politics.

Jonathan Capehart will host a reporter debrief followed by a roundtable discussion with

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