Global warming: Point of no return to avoid 2-degree rise may be 2035

The
world is approaching a “point of no return” for dealing with
climate change.
AP / Ed
Wray

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There’s nothing mysterious about what it will take to limit
climate change: The world needs to transition away from fossil
fuels towards renewable energy.

But the timing of that transition is extremely important.

According to a new study
published in the journal Earth System Dynamics, we could soon
cross a point of no return. After that, it’ll be almost
impossible to keep Earth’s temperature from rising 2 degrees
Celsius.

The goal of the Paris agreement was to cut emissions enough to
keep the planet from crossing that limit, since scientists have
determined that more than 2 degrees of warming could have
catastrophic effects.

The new study calculates that if the world’s governments don’t
initiate a transition to clean energy sources by 2035 — meaning
that the share of renewables starts to grow by at least 2% each
year — we’ll almost certainly pass that point of no return. 

The exact year could change, according to the researchers’ model,
if new technology can remove greenhouse gases from the
atmosphere, or if we see quicker growth in renewables. But no
matter what, the deadline is coming soon.

“In our study we show that there are strict deadlines for
taking climate action,” Henk Dijkstra, a professor at
Utrecht University in the Netherlands and one of the study
authors,
said in a statement. “We conclude that very little time is
left before the Paris targets [to limit global warming] become
infeasible.”

Not hitting those targets makes the
worst effects of climate change far more likely. These
include rising seas that could swamp coastal cities, searing heat
waves that would cause tens of thousands of deaths, drought,
wildfires, and extreme storms.

Flash floods in Oman cut
off roads.

Anita Di
Chiara

A warming world

By burning fossil fuels, we release carbon dioxide and other
gases. Doing so has already altered Earth’s atmosphere in a way
that has led it to trap more heat from the sun. And global
temperatures have crept up — they’ve already risen more than 1
degree C higher than in pre-industrial times.

The more greenhouse gases we pump into atmosphere, the more heat
we trap. That part of the equation is certain.

Skye Gould/Business Insider

As the study authors wrote, “nowadays, the question is not so
much if but by how much and how quickly the climate will change
as a result of human interference, whether this change will be
smooth or bumpy.”

Scientists have calculated how much warming will result from the
release of different amounts of carbon dioxide. The new study
took those numbers and combined them with projections of future
emissions that will continue
to rise as nations develop and consume more energy.

Based on that model, the new study’s authors figured out a
potential “point of no return”: the year 2035, unless the share
of renewables were to start growing by 2% a year before
then. 

That’s an ambitious number, considering that from the late 1990s
to 2017 (in about 20 years), the percentage of energy from
renewables only grew a total of 3.6%.

Greenhouse gases make air
pollution worse.
Shutterstock/J
Dennis

Predicting the point of no return

The authors aren’t saying there’s one decisive point after which
all hope is lost. 

If global energy use were to rise faster, the switch to
renewables would have to happen sooner.

On the other hand, if the share of renewables were to grow by 5%
a year instead of 2%, that could push the date back 10 years. The
development of negative emissions technology that could suck
greenhouse gases out of the air could also push back that
no-return date. But even that would only give us six to 10 extra
years — and the switch to renewables still would be required.

Regardless of these caveats, the study suggests that the clock is
ticking, and it’s going to get harder to meet our goals the
longer we delay.

Searing heat waves and drought are consequences of
climate change that we’re already seeing.
REUTERS/Stringer

Uncertain consequences

In the study, the authors explain that it gets harder to predict
climate consequences and the world’s response to them as the
Earth’s temperature gets higher. 

That’s because research suggests that certain natural systems on
the planet could be activated by warming and consequently trigger
further warming. A recent
paper that explained this concept: if those systems are
triggered at 2 degrees, it said, that might cause temperatures to
spike even higher regardless of how we control emissions. The
study dubbed this scenario “hothouse Earth.”

In that situation, Earth’s average temperature could rise 4 or 5
degrees Celsius above pre-industrial levels, leading to sea
levels up to 200 feet higher than they are now.

Because of that uncertainty, the paper’s authors hope that
establishing a timeline for a potential point of no return will
spur the world’s leaders (and voters) to act sooner rather than
later.

“We hope that ‘having a deadline’ may stimulate the sense of
urgency to act for politicians and policy makers,” Dijkstra said
in a statement. “Very little time is left.”